CA1286390C - Method of and system and apparatus for locating and/or tracking stolen or missing vehicles and the like - Google Patents
Method of and system and apparatus for locating and/or tracking stolen or missing vehicles and the likeInfo
- Publication number
- CA1286390C CA1286390C CA000533481A CA533481A CA1286390C CA 1286390 C CA1286390 C CA 1286390C CA 000533481 A CA000533481 A CA 000533481A CA 533481 A CA533481 A CA 533481A CA 1286390 C CA1286390 C CA 1286390C
- Authority
- CA
- Canada
- Prior art keywords
- transponder
- vehicle
- signals
- reply
- command
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- G—PHYSICS
- G08—SIGNALLING
- G08G—TRAFFIC CONTROL SYSTEMS
- G08G1/00—Traffic control systems for road vehicles
- G08G1/20—Monitoring the location of vehicles belonging to a group, e.g. fleet of vehicles, countable or determined number of vehicles
- G08G1/205—Indicating the location of the monitored vehicles as destination, e.g. accidents, stolen, rental
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/74—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B25/00—Alarm systems in which the location of the alarm condition is signalled to a central station, e.g. fire or police telegraphic systems
- G08B25/01—Alarm systems in which the location of the alarm condition is signalled to a central station, e.g. fire or police telegraphic systems characterised by the transmission medium
- G08B25/016—Personal emergency signalling and security systems
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S2205/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
- G01S2205/01—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations specially adapted for specific applications
- G01S2205/05—Anti-theft or abduction
Abstract
ABSTRACT
An improved vehicle or other object-tracking and location system, preferably, though not essentially, of national scope, wherein transponder or transceiver-equipped stolen or missing vehicles or other objects may be located and/or tracked, as by appropriately-equipped police direction-finding tracking vehicles, through homing-in on periodic transponder reply radio transmis-sions automatically activated by command activation signals broadcast on the same carrier frequency as the transponder reply signals and with encoded vehicle identi-fication information that causes the intended vehicle transponder so to reply, and with provision for modifying the command signals to require an increased rate of periodic transponder reply signal transmission to assist homing-in on the selected vehicle. In a preferred mode of operation, the verification of whether the reportedly missing vehicle is thus transponder-equipped is preferably established by querying the FBI-NCIC computer system, which will provide the said coded vehicle identification information ant automatically cause the appropriate sector or area to broadcast said command activation signals.
An improved vehicle or other object-tracking and location system, preferably, though not essentially, of national scope, wherein transponder or transceiver-equipped stolen or missing vehicles or other objects may be located and/or tracked, as by appropriately-equipped police direction-finding tracking vehicles, through homing-in on periodic transponder reply radio transmis-sions automatically activated by command activation signals broadcast on the same carrier frequency as the transponder reply signals and with encoded vehicle identi-fication information that causes the intended vehicle transponder so to reply, and with provision for modifying the command signals to require an increased rate of periodic transponder reply signal transmission to assist homing-in on the selected vehicle. In a preferred mode of operation, the verification of whether the reportedly missing vehicle is thus transponder-equipped is preferably established by querying the FBI-NCIC computer system, which will provide the said coded vehicle identification information ant automatically cause the appropriate sector or area to broadcast said command activation signals.
Description
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METHOD OF AND SYSTEM AND APPARATUS
FOR LOCATING AND/OR TRACKI~G STOLEN
OR MISSING VEHICLES A~O THE LIKE
The present invention relates to methods of and sys-tems and apparatus for tracking stolen or missing vehicles and the like, being illustratively described in connection with its important and perhaps primary application to the recovery of stolen or missing automobiles and the like.
In U.S. Letters Patent No. 4,177,466 of common assignee with the present invention, an automobile theft .
detection system was proposed involving the concealment in protected automobiles or other vehicles of radio trans-celvers or transponders responsive to radio signal trans-missions sent when vehicles are missing, and modulated with a code corresponding to the missing vehicle identifi-cation; each particular missing vehicle transponder ,, i v~
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'~ ' , .. ' ' ' . , ~, : . ~ " ' lZ~t~390 transmitting the same transponder locaeor signal when its iden~ification code is received for tracking by a police or other direction-fin,der vehicle. To implement a system or this character in practice, however, far more sophisticated techniques and safeguards are required, including the use of a single frequency for all trans-missions and the problems of time-sharing dictated therebyt with protection against transponder transmission while other transmissions on that frequency are in pro-gress; adaptability for varying the rate of transponder transmissions on initiated by request of the operator of the tracking receiver to provide faster or stepped-up periodlc reply signals for homing-in on the vehicle; dis-crimination of different vehicle transponder reply trans-missions for tracking; checks to insure against false transponder activation; and the solution of other prac-tical usage problems such as the required police or other identification information storage and networking require-ments for a universal, nationwide and/or at least state-wide system.
:, An ob;ect of the present invention, accordingly, is to provide an improved and highly practical method of and apparaeus for locating and tracking stolen or missing vehicles and the like thae, while e~ploying prior underlving concepts of,unique signal code-responsive transponders, provides the added sophistication, securitv and practical techniques found essential to enable a commercially useable universal system.
A further object is to provide such a s-ystem wherein, for the case of automobile theft, the vehicle owner need only report the theft, after which the entire system operates under the direct control of law enforcement equipment and personnel, with the system virtually insensitive to disarming or accidental activation.
Another object is to provide an improved transponder apparatus for ideneifying an object or vehicle with which it is associated and, where and if desired, permitting location of such object or vehicle.
It is a further object of this invention to provide such a transponder which broadcasts at a variable rate a reply code specific and unique to that transponder to establish its identity.
It is a further object of this invention to provide such a transponder for which such broadcast rate is .~
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lZ1~36390 externally controllable.
It is a further object of this invention to.provide such a transponder which permits individual location of simultaneously broadcasting transponders on the same reply frequency.
It is a further object of this invention to provide ~ such a transponder apparatus which can réceive an j actlvation code ant transmit its reply code on the same frequency.
The invention results, in part, from the realization of a truly effective vehicle transponder that can detect encoded information, provide a reply code specific to the ,' transponder, discern the presence of a specific identification code and a broadcast.rate command in the ~, encoded informatlon, and determine the transmission period for the reply code based on the broadcast raee command.
Other and further ob~eccs will be explained hereinafter and are more fully delineated in the appended claims.
In summary, however, from its overall aspect, the invention embraces a method of tracking a computer-'; registered transponder equipped vehicle and the ~, "'~'i' ' $~
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~Z~3G390 like, upon the same being missing, that comprises, checking the registration of such vehicle to determine that it is computer liste'd as transponder-equipped; upon affirmative determination of such transponder equipment listing, initiating the broadcasting in an appropriate sector of a radio activation command signal carrying coded identification unique to said vehicle and its transponder; recelving said command signal at the vehicle transponder, decoding the identification and verifying that the same is the unique code of said vehicle and its transponder, and, if so, causing the transponder to become activated to transmit periodic vehicle reply signals including unique identification; receiving said periodic vehicle reply signals in a tracking vehicle and locking onto the same; thereafter, at the request of the tracking vehicle, modifying the said sector radio activation command signals to provlde increased-rate command signals to the vehicle transponder; and responding to the increased-rate co~mand signals at the vehicle transponder to increase the periodicity of the transmitted transponder vehicle 8ignals to facilitate tracking by the tracking v-hlcle.
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-:- - ~ . . :. -From other viewpoints, the invention also involves a novel transponder apparatus for use in identifying the presence of an object interrogated by broadcasted radio activation command signals on a predetermined RF carrier carrying coded identification unique to that object and its transponder, the apparatus having, in combination, means for receiving said command signal and for decoding the ldentificatlon and verifying that the same is the unlque code of said object and its transponder; means operable in the event of such verification, for activating the transponder to transmit periodic reply signals on the same carrier frequency and including unique identification thereupon; and means responsive to further command signals requesting a variation in the rate of such reply signals for thereupon transmitting the reply signals at such varied rate.
From still another aspect, the invention provides a transponder apparatus which detects encoded informacion, discerns the presence of its specific and unique identifi-cation code and a broadcast rate command in the encoded information, and transmits a reply code specific to the transponder, while determining the next time of trans-3~0 mission of the reply code for periodically repeating suchreply transmissions. In one construction, the transponder monitors RF command signals for predetermined encoded audio signal carried by the broadcast signal. The audio signal conveys encoded digital information using different audio frequency signals or tones, to define the informa-tion, which typically includes a broadcast rate command for the transponder replies and an identification code ~pecific and unique to that transponder (although in certain instances a universal identification code such as a universal test code may be substituted for the specific identification code). The transponder converts the digi-tal information lnto digital logic signals and, if the specific identification code is present, broadcasts a reply code, specific to the transponder, repeatedly at a rate determined by the externally controlled broadcast rate code command, which may be changed to vary the trans-ponder reply rate. ~utual interference with both recep-tion and transmission is avoided with the preferred single carrier frequency employed, by pseudorandomly varying the transmission period. A number of activated transmitters, moreover, can broadcast simultaneously on the same RF fre-:~ .
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quency as well as monitor that frequency for additionalcommands.
And, in another feature, the invention further pro-vides a transponder vehicle tracking apparatus having, in combination, direction-finding means for receiving activaeed vehicle transponder periodic radio reply signals carrying vehicle identification code information; signal -and microprocessor means for demodulating said identifica-tion code information and for alpha-numerically displaying the same; means also responsive to the last-named means for simultaneously displaying both the bearing from which the transponder reply signals are received and the signal strength thereof; and means for locking onto and displaying only radio reply signals of a selected vehicle transponder.
Mention should also be made of the feature of using non-volatile memory to remember the state of the transponder so that if electrical power should be removed after activation, when electrical power is restored to transponder it will continue to transmit reply code without need for re-activation.
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_9_ details are later explained.
The invention will now be described with reference to the accompanying drawi~gs, Fig. 1 of which is a syste~
diagram of the preferred vehicle location system application of the concepts of the invention;
Figs. 2 and 4 are bloc~ circuit diagrams of a transponder or transceiver apparatus particularly designed for use in the vehicles-to-be-tracked in the system of Fig. l;
Fig. 3 is an encoded infor~ation sequence useful with the system;
Fig. 5 is a flow chart of the operation of the receiving and transmitting functions of the transponder of I Figs. 2 and 4;
Figs. 6 and 7 are block circuit diagrams of a preferred vehicle tracking receiving and display systems for homing-in on the reply signals of the transponders of Figs. 1, 2 and 4; and Fig. 8 is a data flow diagram of the sector activation computer-controlled broadcast command system providing radio signals eo interrogate and activate the vehicle transponders of the invention.
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12~3~3~0 A descripeion, first, of the overall philosophy and methodo.logy underlying the total system operation of the invention in preferred form is in order, with reference to the Svstem diagram of Fig. 1.
Uhen a vehicle V (or V') equipped with the trans-ponder T (or T') of the present invention is lost, the owner reports that fact to the local police department which, in turn, reports to a state computer station system S. In tests in Massachusetts, this system, as later explained, is termed LEAPS. This information is sent, as a matter of course, from station S, as by telephone network or link L, to a master computer file, preferably maintained, for example, by the National Crime Information Center (NCIC), a part of the FBI in Washington, D. C., (or at other suitable computer facilities) and whereat it is intended. to have in storage (SVLS -- stolen vehicle location system), a list of the vehicle identification numbers of registered subscribers to the theft system of the invention. Every stolen car report that comes in, will be checked against the subscriber list (SVLS data base), and if a match is found, a computer message will be sent back at L to the originating station S, with a - :-.
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set of information that includes a unique activation codeand a unique reply code for the transponder of the stolen vehicle, and a descriDtion of the vehicle. This informa-tion, now a~ the compucer LEAPS) at location S, is used to cause a controlling computer (SV~S computer) to set up a transmission schedule and, as by microwave link M, initiating the transmitting of the activation code from a series of radio broadcasting transmitting antennas B (B'), operated sequentially or lf sufficently spaced, simultaneously or in slave fashion, thereby causing the stolen vehicle transponder, if in the area or section, to activate with a certain probability. The activator code is broadcast periodically (schematically shown at C) until a report is received that the car has been retrieved or until some predetermined time interval has been exceeded.
These activation command signals broadcast at C, have the activation code of the vehicle transponder, check-sum digits, and certain command bits that cause turn-on, turn-off and speed-up, as later explained.
As before stated, the frequency of the broadcast transmiteer~ is the same as that of every vehicle trans-ponder; namely, for example, a nationally assigned V~F
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'~ ' , '' law-enforcement frequency. But each transponder T (T') transmits a digital coded response or reply of about a tenth of a second durat~on, periodically and preferably at pseudo random intervals, say, once every ten seconds, roughly. In accordance with a feature of the invention, however, if the transponder detects another transmission on the frequency, it waits until that message is completed and then commences its reply transmission.
A police or other tracking vehicle TR, appropriately equipped with a direction-finding antenna system A and a trac~ing receiver and display D, when within range of the missing vehicle, will display on an indicator panel the coded response of the vehicle transponder, received along schematic path(s) R (R'), a five-digit alpha-numeric code corresponding to the code being transmitted by the vehicle transponder T (T'). When the police officer sees that display at D, the officer calls into his radio dispatcher, via RD, who puts an inquiry at P into the state computer (LEAPS) and inquires as to the status of that code. If it turns out that this is a vehicle that is stolen or that ic is otherwise desired to track, then the sector broadcast transmitters B (B') will be activated to send out a .
12E~t~390 different transmission C distinguished from the first activation signals to vehicle transponders T (T') in that it represents a request to increase the periodicity or rate of vehicle transponder responses or replies. The second, step-up or speed-up reply request command signals C will have the same vehicle identification nûmber, it may or may not have the same check-sum bits as the first type activation command signals, but it will have a different code in the command section of the message, causing the speed-up, as opposed to just turn-on.
When the vehicle transponder receiver receives this increased rate command signal, the transponder circuits will cause the transmission of the coded reply or response message signal from the transponder vehicle to be accelerated to a faster rate of transmission, say about once per second, along R (R'), so that those in the track-ing vehicle TR, instead of seeing the coded number once every ten seconds on the display, will see it once every second or so to aid in homing-in. The transponder will stay in that speeded-up mode for a period of time, say 30 minutes, and then automatically return to the regular mode ., .
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~Z~6390 of transmitting once every ten seconds, the expectation being Ghat within a half hour, the vehicle ough~ tO have been recovered.
If recovery has not been made, the tracking vehicle can always ask for the speeded-up vehicle transponder reply command request to be broadcast again at B (B').
At the tracking vehicle TR, not only are vehicle transponder reply codes displayed, but a lock select or control (button, for example) is provided at D to cause the computer processor in the tracking device to display only signals with a particular reply code from a par-ticular vehicle transponder, to the exclusion of other vehicle transponder signals as from other stolen vehicles in the area. In addition to the reply code display, the . tracking vehicle installation is provided with a direction indlcator such as a circle of light-emitting diodes that gives relative bearing or direction of reception of the transponder signals. The direction-finding system at the tracking vehicle preferably employs four roof antennas A, later discussed in connection with the embodiment of Fig.
6, that are electronically phased to determine the incom-~ ing signal by determining the Doppler shift, as is well-'~:
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12~3~i390 known, and providing the bearing indication.
In addition to the bearing indication, a bar-graph indicator is further provided at D that shows relative signal strength and thus a rough indication of range.
This is important in tracking, particularly in urban environments where the signal can bounce off a building or other vehicles and trucks that may be close by. The signal that comes from the direction of the stolen vehicle wlll usually be the stronger; so that if the tracker sees the signal strength display in erratic mode, the direction of maximum signal strength is followed.
The tracking vehlcle personnel, as they home-in, thus know the relative dlrection, the relative signal strength and a complete description of the vehicle being sought;
and, of course, other information that may be pertinent such as whether the car may have been involved in an armed robbery or some other important aspect. After finding and securing the sought vehicle, the personnel of the tracking vehicle will repore that the car has been retrieved so that the system may cancel the stolen car report in the NCIC and other computer files. Again, in accordance with preferred features of the invention, this is also .
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automatically effected, with the software at NCIC checking and issuing a new set of command instruceions which causes the turn-off of the command sign~ls previously broadcasted in the search sector. Other aspects or preferred refine-ments in the best mode of practice of the system of the invention include the following. Messages that come in to the computer controlling the broadcast transmitters are queued up before being transmitted because it takes a certain amount of time for the trasmitter to build up to full intensity, which amount of time is of the same order of magnitude as the messages-to-be-sent. The sector broadcast transmitters will send out their activation signals and codes on a periodic bases, perhaps once an hour or so, as before indicated, until the vehicle is either recovered or a certain period of time has gone by, which may, for example, be set at a month.
From a practical viewpoint, it is important to have some way of checking out the eransponder system once it is installed in the car. This may be effected by an installation test unit, later described in connection with the functional or operational diagram of Fig. 5. This insea11ation cese unit is capab1e O e sending a signal to ", ~' -.
~2~;;390 the transponder receiver portion T-R~ which the trans-ponder recognizes as a signal coming from the test device and which causes the transmitter section T-T~ of the transponder T to go into a low power mode, in response also to another safeguard signal that it picks up on it's DC power line, simultaneously.
In this preferred nationwide cooperative system illustrated in Fig. 1, (though the invention is also useful for smaller sectors, states, group of states or other sector sub-divisions as well), thus, each vehicle transponder or transceiver assembly is part of a national (or at least wide-area) stolen vehicle location system, as above indicated, shown as preferably coordinated with the National Crime Information Center, NCIC.
When a vehicle such as automobile(s) V (V') is reported stolen, information such as the license is entered through terminals P at any of a number of terminals disposed throughout the area being monitored, such as in local police stations or other municipal build-ings, all such cooperating with the before-mentioned LE~PS
computer which has access to information as to the manufacturer's vehicle identification number, description, ., ~ ' ' :, .
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, 1213~;390 etc. This is a procedure followed in recent testing of the invention in Massachuse~ts. The LE~PS computer interacts via L with the SVLS data base, to determine if the vehicle is equipped wi~h a vehicle transponder T
according to this invention. The vehicle identification number is sent through the federal communications tele-phone or other networking L to the NCIC computer in Washington, D.C., where, according to the preferred mode of the invention, once the vehicle is identified (from compari90n with stored data) as a subscriber equipped with such transponders, the SVLC software accesses the SVLS
data base at NCIC to determine the unique activation code for the vehicle V (V') and the unique reply code which that transponder will broadcast upon activation. The activation code and reply code information are returned automatically through network L to the LEAPS computer which engages the SVLS computer and as through microwave control link ~, relays the code information to the radio tranYmitter at B to broadcast an RF carrier command signal containing on its carrier frequency the vehicle activatiOn code and including the specific unique vehicle identification code and a command for the transponder to .`,~ ' :, .
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~Z86390 reply ac a particular rate.
Let it be assumed that vehicle transponders T and T', hidden within cars V and V', respectively, are both in range of sector activation transmitter B, as shown. Only transponder T, however, will respond to the unique identi-fication code broadcast along C by transmitting antenna B. Upon activation, transponder T then broadcasts its reply code unique to it which is then received at D by the tracking vehicles such as a police cruiser TR. The code name for car V i9 thus displayed on a console at D. The tracking officer relays this code name along radio link RD
to the police dispatcher, who accesses the LEAP and SVLS
computers at S to obtain a description of the vehicle V, which is then radioed back to cruiser TR so that the officer can visually identify the vehicle V.
As before stated, homing-in can be facilitated by step-up or increase of the periodicity of transponder reply signals as the tracking cruiser enters the vicinity of the stolen vehicle V. By requesting such speed-up via link RD, the SVLS will control the before-~entioned increased rate request, causing the signals broadcast at C
to command such step-up in transponder reply rate.
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Turning, now, to details of preferred implemenea~ion of the various components of the system of the invention, a useful transponder or transceiver configuration T is illustra~ed in Fig. 2, wherein an antenna 1, hidden in the vehicle V (as inside the seat backs, dashboards, etc.), is connected to a switch 3, such as conventional PIN diodes or the like, for switching the antenna to the receiving or transmitting circuits of the apparatus at appropriate time8.
Assuming that the switch 3 is in the receiving func-tion, the antenna 1 is then connected to an RF amplifier and then a mixer so-labelled, which, with the mixing of a local oscillator (lst LØ), takes the carrier frequency of the activation command signals C broadcast by B (B') down to a first intermediate frequency, say from a specified VHF carrier (narrow-band FM audio FSK signal) to an intermediate frequency of 10.7MHz. This is filtered and then applied to demodulator, so-labelled, that basically extracts the audio from the signal. That audio comprises two tones, one of which corresponds to a logical "zero' and the other of which corresponds to a logical "one". The purpose of the modem 5 receiving these .
: ' . ' .' ' 3~30 filtered tones is to convert the tones into digital voltage levels, corresponding to the "zero" and "one".
The converted logic levels are applied to a microprocessor 5' which serves as a control device.
When the vehicle code has been identified, as later explained, and it is desired to reply or respond with nique vehicle code periodic transmitted signals, as before explained, the microprocessor 5' generates logical levels which it then feeds to the modem 5 to convert those logic levels back into tones which are fed into a modu-lator so-labelled, in the transmitter (bottom) portion of Fig. 2. The modulator modulates the transponder trans-mitter T-TX consisting of an oscillator, a frequency tripler to bring the frequency to that of the input com-mand signal carrier. The transmitter is a driver and a power amplifier (power amp), adapted to feed the trans-ponder antenna to transmit the reply signals R (Fig. 1) on the same carrier frequency as the broadcast activation command signals C, when the switch 3 connects to the power amplifier under the control (via 3') of the microprocessor 5'. A high-power switch (Hi-power), is also shown controlled by the microprocessor 5' to bypass the last-3'~0 named power amplification seage (power amp) so that a mode for low-power test and installation transmissions is pro-vided.
An e~ample of coded information originally carried by the broadcast command activation signals C as F~-modu-lation and received by the vehicle transponder T is shown in Fig. 3. The preamble I comprises initially sequential digital logic "ones" and "zeros" which allow modem 5, before mentioned, to synchronize with the signal. The next block II, labelled "Flag", indicates the commencement of the following data frame containing the information conveyed by the two audio tones (say, of 1200 and 1800 Hz frequency) representing logical "ones" and "zeros". When the signal C is intended solely for the transponder ~ of missing vehicle V, the transponder code III represents the unique digital address for transponder T. The rate com-mand portion IV is an activation command, a deactivation command, or a step-up transponder reply periodicitycommand represented by one or more values in binary form. Las~ly, the frame may further include conventional redundancy checks V, shown dotted, such as cyclic redundancy checks, ., , .
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12~36390 vertical redundancy checks, or longitudinal redundancy checks which permit error correc~ion and detection of transceiver code III and rate command IV.
Using the code information of Fig. 3 as exemplary, the corresponding encoded information may be traced through the transponder circuit of Fig. 2, as follows.
When the FM-RF signal C having the preselected carrier frequency ls received, the same is demodulated, as before explalned, producing the carried audio slgnals represent-lng the desired digltal information. The modem 5 converts the audio slgnals lnto digltal slgnals, as prevlously ; stated, and microprocessor 5' recelves the digital infor-mation when the audio signal is, say,. in the range of 1100 ~ to 1900 Hz. The modem 5, such as, for example, Type 409 ; of MX-COM Inc., of Winston-Salem, North Carolina, outputs a logical "one" for one cycle of 1200 Hz, and a digital "zero" or one and one-half cycles of 1800 Hz in the above ; example. Microprocessor 5', such as, for example, Type MSM5840RS of OKI Semiconductor, Inc., Santa Clara, California, processes the encoded digital information as follows. A nonvolatile memory 7, such as an EEPROM
(electrically erasable programmable read-only memory) or , ~ other PROM cooperates with the microprocessor 5' and .~, .,~, ? ~
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~2~3~390 contains the specific vehicle transponder identification code, to be compared with the encoded digital information III, Fig. 3, and ehe matching transponder reply code. To conserve power, this memory 7 is provided with power only when retrieval of its information is required. In combin-ation with the feature that inter~ittent or periodic transponder reply signals are generated only upon command, as described, the transponder efficiently conserves power. The car battery +,- or other battery provides power at twelve volts to a power regulator 9 which main-tains a five-to-six-volt power outpout to the micropro-cessor 5'. A voltage level detection circuit 11 resets the microprocessor 5' when the voltage drops below a pre-determined voltage, thereby allowing it to complete routine housekeeping while sufficient power remains. As an example, the most recent rate command can thereby be stored in the nonvolatile memory 7 before power is totally lost.
For testing purposes, the microprocessor 5' may .
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12~i390 broadcast a test reply signal when a universal RF tese signal is received simultaneously with an electrical signal of predetermined special frequency on the unit's D.C. power supply (as detected by a power signal de~ection circuit 13). The special signal is of frequency high enough so that the impedance of battery +, - does not interfere with signal detection, and low enough so that a test signal does not create BF interference. The special electrical signal is required so that the test device cannot be used by an authorized person to locate cars equipped with the transponder of the invention.
Returning to the normal operation, when the proper identificatlon code is received, microprocessor 5' recalls lts specific reply code from the nonvolatile memory 7, stores lt in RAM, and submits the information to the modem 5 which converts the digitally encotet information back into an audio signal. As before explained, with antenna switch 3 dlsabllng connection to the receiving part (T-R~) of the transponter, the transmitter portion (T-TX) on activation of the transmit switch 15, under control from the microprocessor 5', transmits on the same carrier frequency the reply FM signals carrying the audio cote ''' , .
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3~0 reply signal; but only if the microprocessor 5' coneroll-ing antenna and transceiver switches 3 and 15, does no e receive indication from modem 5 that ~he receiver portion is still receiving a transmission on the carrier frequency; otherwise, the control signal awaits absence of such carrier frequency. As before stated, the use of the non-volatile memory enables the transponder to continue replying after an interruption in replying caused by power failure.
The microprocessor 5' includes an operation for lnterpretlng the broadcast rate command when received with the iden~ification code specific to a particular vehicle transponder T. A schematic implementation of this part of the operation in hardware form is shown in Fig. 4, such being considered as effectively incorporated in the pro-cessor 5' of Fig. 2. In actual practice, of course, con-ventlonal software control will be provided, the hardware explanation, however, more facilely describing the opera-tional functions. Specific identification (ID) code comparator 17 matches the received identification code with the identification code stored in RA~, after it is accessed fro= the notvo1ati1e =emory 7 oi Fig. Z. Ii the ~ . _ ~2~3~0 identification codes match, the broadcast rate command is provided to rate i~terpreter circuit 19 which selects a reply broadcast rate at s~itch SW. If the rate command is "00", Fig. 4, for e~ample, pseudorandom generation circuit 21 is accessed, this circuit periodically receiving a pulse from a clock 23 and delaying signalling trans-mitter-enable circuit 25 by an additional amount of time represented by a pseudorandomly generated number. For example, clock 23 may provide a pulse every 8 seconds, and circuit 21 may generate an additional delay period of O to 4 seconds, resulting in the about once per ten second rate of periodic reply signals as the enable circuit 25 is signalled to command transmission of the replies.
When a step-up or increased reply rate command is received ("01"), such as after a police cruiser nears the stolen vehicle, a step-up clock 27 is accessed, as by switch SW effectively moving to the position shown in Fig. 4, the clock 27 generating a pulse at short, regular intervals, such as once every second, which triggers enable circuit 25 to continue transponder transmission at that rate and also steps up the pseudo random circuit.
After a predetermined period of time, clock 27 , :
-~Z~363~0 signals rate interpreter circuit 19 through line 21' to return to the normal broadcast rate (Sw position "01"), whereupon normal reply activation rate continues until a deactivation com~and "02" is received, at which eime switch SW contacts ground to cease transmissions.
One suitable operation logic for the transponder T is shown in Fig. 5. In receiver T-RX, represented by opera-tional step 3~, the frequency of the incoming carrier signals C is monitored, and unless received, the monitor-ing continues at step 31. If the received carrier fre-quency is valid and the audio signal thereupon is within the preselected frequency range, step 33, the encoded information enters the modem 5 and microprocessor 5 t for processing (RX-AUDIO 11, Fig. 2).
The transponder may include a testing feature, indicated in dotted lines as step 35, where an RF test signal carrying a test code within the correct audio range may trigger the transponder T-TX to b~oadcast a test reply signal, step 37. For test step 35 to be satisfied, a pre-selected signal detection circuit 13 of Fig. 2, earlier described must detect the appropriate signal on the D.C.
power line.
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~29-Lf the testing feature or the criteria for entering its subroutine are not present, the specific transponder code for the vehicle V is recalled from memory in step 39 and compared to the converted audio tone digital inror-mation on the incoming signal. When the specific trans-ponder code is not present, monitoring continues, step 31;
but if the specific transponder code is discerned, the rate command is relayed, line 61, and is distinguished within the trànsmission command procedure 41 to determine transmission of the reply code by the transponder trans-mitting portion T-TX. When a deactivation command is present from the broadcast signal C, step 43, the tran~ponder T ceases broadcasting replies, 45, and then, as indicated by line 59, resumes monitoring, step 31.
The presence of the transponder activation command of broadcast signal C is determined in step 51, and of the reply rate step-up request command, at 47. The trans-ponder ls activated to reply, or it receives the step-up rate command to replay at a greater periodic rate. The step-up command, as before explained, may remain in effect until a deactivation command is received or until a pre-determined period of time has elapsed.
' .
" ~ ' - ' ' --1Z~639`~:) When the activation command is received, a broad-cast-enable is generated pseudorandomly, step 43, at an average rate which is slower than the step-up rate; for e~ample, "enables" may be generated in step 49 once every second, as before discussed, whereas the normal reply "enable" may be generated, step 53, once every 10 seconds or so, including plus or minus a random number, thereby minimizing the chance of overlap with the reply broadcasts of other activated transponders. Preferably, after each new rate command is received, it is stored in nonvolatile memory, shown dotted at 55, and corresponding to the memory 7 of Fig. 2. Conventional error correction and detection can be performed on the incoming data in steps 39 and 41 by means of well-known vertical, longitudinal, and cyclic redundancy checks, as previously mentioned.
It is now in order to examine the necessary type of circuits for the tracking vehicle receiver equipment TR, Fig. 1, a preferred form of which is illustrated in Fig.
6. The tracking receiver has two main parts; a radio-receiving, power and processing portion; and a display, portion D. The receiving pcrtion comprises an RF summer 2 that multiplexes the inputs from four antennae of the i286390 tracking vehicle direction - finding antenna system A
(Fig. 1): J 4, J5, J6, and J7. The sum of the four inputs generates the signal from which the user is able to determine the direction of either a vehicle transponder T
being tracked or any device that may be jamming the vehiclettransponder. The summer output contains the very high frequency carrier signal of the vehicle transponder coded reply with response signals and is fed to a narrow band FM receiver 4 which "strips off" the infor-mation-carrying signals in the audio range (1200 and 1800Hz and the Doppler modulation frequency from the direction-finding, such as 422 ~z), and supplies that demodulated audio signal to the tracker's microprocessor and signal processor 6. The microprocessor portion decodes the reply code of the vehicle being tracked and the signal processor determines the car's direction, as later discussed.
The receiver also provides the signal strength level that indicaees the stolen car's distance from the tracking vehicle, as also hereinafter more fully explained.
3~0 The power for the eracking receiver, which may range from 11.5 to 14.5 volts, is supplied by the police or other tracking vehicle in which the device is mounted.
The power supply ? and SP cloc~ and filter circuit board 10 supplies all the power necessary for the functioning of the tracking device, contains the master clock for the signal processor 6, and does some preliminary filtering of the signal for the signal processor.
The signal processor board 6 has two functional parts: a control voltage waveform generator and an audio signal processor, The control voltage waveform generator portion provides the signals (VCA, VCB, VCC, VCD) that are necessary for the RF summer 2 to multiplex s~oothly from one of the four antenna signals to the next, in conventional fashion. These four signals, which are all identical, are shifted 90 degrees according to a precise curve calculated from PROMs contained on the board. The audio signal processor portion, on the other hand, takes the filter signal from the power supply board and performs additional filtering, which serves to make apparent the before-mentioned Doppler shift that indicates the direc-tion of the car being tracked.
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' - ', - ~ ' : ' : ' ~2~3~0 The primary function of the logic/demodulating board 8 is to take the signal strength from the receiver 4 and convert it into digital form. It performs that function by de~odulating the received signal into a stream of O and 1 bits that contain both the reply code of the car being tracked and a number of error detection and correction bits. The logic board also reads and controls the syste~
display D.
That display/control portion D, which may be mounted on the dashboard of the trac~ing police car, contains two boards: one for displays (Dl) and one for the display logic (D2) -The display D2, more particularly delineated in Fig.
7, consists of an array of LEDs, arranged in a circle 12 and representing compass points, as well as a central LED
12' that serves as a point of reference (particularly at night) for those around the circle's edge. There is also a bar graph BG with LEDs that indicate relative signal strength by the height of the lighted display. Another LED 12" placed next to the bar graph BG indicates wheCher the bar graph display is on the local or distant display range.
..
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~2~;3~) At the upper center of the display is a 5-charac~er alphanumeric display CD that shows the reply code of the car being tracked.
There is also a lock-unlock switch 14 that enables the user to lock onto a particular reply code. When the switch is not in the lock position, each code from all of a multiplicity of vehicle transponders within range of the tracking vehicle shows for one second.
The preferred alphanumeric display at CD is effected from data clocked from the microprocessor 8 (G~, Fig. 7) into a pair of 8-blt shift registers SR, the first bits controlling which of the LED dot-matrix display unit of CD
are used to display a given character ~left), and the following comprise the code for a given character, so as to produce an alphanumeri.c display containing the unique code or serial number of the vehicle transponder which is ~ending the reply signals R to the tracking vehicle. In a practical implementation, a thirty-five bit shift register SR', controlled by clock C', which is in turn supplied with control outputs G1 - G3 from the microprocessor logic demodulator 8, receives information for the compass point : ' ~, .
~ :, ~' : ''' l'Z~63~t0 L~D display 12> the on/off (po~er) control LED 12', the local/distance LED 12' and the bar graph BG -- all as clocked sequentially into the shift register SR'. On the 36th clock pulse from the clock C', the daea is laeched and outputted to the appropriate LED's.
In summary, when the tracking vehicle equipment TR is turned on, but is not receiving a signal, the direction lndicator display 12 (Fig. 7) is blank, the signal strength indicator display BG reads O, and the code dis-play C~ is blank. In this mode, any received vehicle transponder signal R of proper carrier frequency will trigger the TR. When such a signal is received, the tracking indicator 12 illuminates to show the bearing of the received signal and the signal strength indicator BG
indicates a relative signal strength value.
If the received signal is a coded vehicle transponder signal, a five character identifier for that vehicle transponder appears in the digital display CD. As the tracking vehicle approaches the vehicle, the sig,nal strength increases. If the distance is increasing, the signal strength will decrease. In urban areas and other places where there are standing waves and reflections, the signal strength may not give a reliable indication of .. , ~ `', ~ ' '' ' ` ~ .
lZ~63~3 relative distance at all times, but provides homing-in assistance eventually. In case more than one vehicle transponder is being received, the loc~ switch 14 can be operated when the desired vehicle's code identifier is displayed at CD. This causes the TR to trac~ only that specified vehicle. When, moreover, the TR displays a normal message from a vehicle transponder, the center LED
12' of the direction display is illuminated.
Finally, the data flow operation for the sector activation transmitter(s) B (B', etc.), Fig. 1, will now be addressed, with reference to Fig. 8 and with common letter part identification with Fig. 1, and with the assumption that the operation will be a national system with NCIC reports on stolen vehicles which go into the national vehicle ~ile DG at NCIC. The stolen vehicle report is entered by local police and dispatcher terminals P (E6, E1) to the state LEAPS computer (P7) which communi-cates with NCIC along lines ~ as discussed in connection with Fig. 1. With the implementation of the present invention, NCIC also would store from data entries E8 and master file up-dating P10, the master file D4 of vehicles equipped with the transponders of the invention, labelled ."
~ -lZ863'~0 SVLS data base in Fig. 1. If the reported vehicle was equipped with the invention, NCIC would send back at L not only their normal reply, but an extra message giving the transponder activation and reply codes of the repor~ed vehicle so that this vehicle transponder may be activated for tracking. The state police computer (LEAPS of Fig. 1) would pass that request to the SVLS computer of Figs. 1 and 8 linked up with the terminals of all the police agencies in the state and receiving (from P7 to P5) request for P5 to process such activation request (or a deactivation when the police recover a stolen vehicle and report such). When P5 receives such request, three things happen. ~irst of all, the request is logged at D5. Then an entry is put into a queue D7 for immediate action, with such queue being serviced, say, one entry every 15 seconds either to broadcast activation command signal C or to place the request into the periodic action queue D3. Such activation signals will be broadcast unless there are others waiting, ln which case, it has to wait its turn.
Thirdly, the request is received in an active file D1 which consists of all business relating to activations and de-actlvations that are currently ln process. An , , . . ,:: ' ' :. : . . . .
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.: ' 12~363~0 activation request g~es into ~he file Dl for, say, 30 days, so that over the ne~t month, activation command signals will be broadcasted. Deactivations are handled the same way, although the time limit may be only 24 hours.
Function P2 removes records from the active file Dl older than 30 days if they are not active; and other than 24 hours, if they are not active, logging its activity.
P6, which represents the broadcaster control signals developed by SVLS Computer, services the immediate action queue D7 once every 15 seconds as earlier mentioned, and causes the periodic sector broadcast command signals C to be transmitted from a local transmitter E3 and/or slave transmitters E4 (B and B' in Fig. 1). The P4 (develop action queues functio~) o-perates every hour to renew the active file Dl and a local file D2, later described, and an hours worth of broadcasting material. Old records may be removed from the local file at P3.
The below-mentioned local file D2 contains data which comes rom Pl (process local transactions) originating at the console El of the SV~S computer, containing a file of vehicle tran-ponders which have been entered locally as .
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for test and other special purposes. The console El itself is protected by a system of passwords (D12, Dll) and daee and time eneries (310) so that unauthorized com-mands cannot be entered. Conventional print-out may be available as at E5.
While necessary and designed particularly for the purposes of the present invention, the transponder apparatus of the invention may also more generally be employed where transponder or transceiver operation is useful with a reply code specific or unique to that transponder and which it broadcasts at a variable and externally-controllable or - commanded rate. The identlfication of vehicles or, more generally, objects so-equipped, for example, is of utility in some apparatus, altogether apart from tracking the same.
Though the invention has been described, moreover, in its preferred mode of operation as a national system, clearly, as before stated, the vehicle identification code material and the like may be stored and supplied within the state or other locale without cooperation with NCIC.
Other well-known circuits and apparatus and conven-tionally derived software for performing the stated func-.. . ' .
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lZI 3~ii390 tions than those shown may also be used, as may certain functions be omieted if not desired; and while specified features of the invention may be shown in some drawings and not others, this is for convenience and clarity of description only, it being understood that each feature may be combined with any or all of the other features of the invention. Similarly the particular selection of frequency reply rates, type of encoding, audio tone range, etc., types of tracking, communication and broadcasting antennas, etc., are illustrative of what is believed to be preferred and what has been successfully experimentally tested; but further modifications will occur to those skilled in this art, and such are considered to fall with-in the spirit and scope of the invention as defined in the appended claims.
METHOD OF AND SYSTEM AND APPARATUS
FOR LOCATING AND/OR TRACKI~G STOLEN
OR MISSING VEHICLES A~O THE LIKE
The present invention relates to methods of and sys-tems and apparatus for tracking stolen or missing vehicles and the like, being illustratively described in connection with its important and perhaps primary application to the recovery of stolen or missing automobiles and the like.
In U.S. Letters Patent No. 4,177,466 of common assignee with the present invention, an automobile theft .
detection system was proposed involving the concealment in protected automobiles or other vehicles of radio trans-celvers or transponders responsive to radio signal trans-missions sent when vehicles are missing, and modulated with a code corresponding to the missing vehicle identifi-cation; each particular missing vehicle transponder ,, i v~
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'~ ' , .. ' ' ' . , ~, : . ~ " ' lZ~t~390 transmitting the same transponder locaeor signal when its iden~ification code is received for tracking by a police or other direction-fin,der vehicle. To implement a system or this character in practice, however, far more sophisticated techniques and safeguards are required, including the use of a single frequency for all trans-missions and the problems of time-sharing dictated therebyt with protection against transponder transmission while other transmissions on that frequency are in pro-gress; adaptability for varying the rate of transponder transmissions on initiated by request of the operator of the tracking receiver to provide faster or stepped-up periodlc reply signals for homing-in on the vehicle; dis-crimination of different vehicle transponder reply trans-missions for tracking; checks to insure against false transponder activation; and the solution of other prac-tical usage problems such as the required police or other identification information storage and networking require-ments for a universal, nationwide and/or at least state-wide system.
:, An ob;ect of the present invention, accordingly, is to provide an improved and highly practical method of and apparaeus for locating and tracking stolen or missing vehicles and the like thae, while e~ploying prior underlving concepts of,unique signal code-responsive transponders, provides the added sophistication, securitv and practical techniques found essential to enable a commercially useable universal system.
A further object is to provide such a s-ystem wherein, for the case of automobile theft, the vehicle owner need only report the theft, after which the entire system operates under the direct control of law enforcement equipment and personnel, with the system virtually insensitive to disarming or accidental activation.
Another object is to provide an improved transponder apparatus for ideneifying an object or vehicle with which it is associated and, where and if desired, permitting location of such object or vehicle.
It is a further object of this invention to provide such a transponder which broadcasts at a variable rate a reply code specific and unique to that transponder to establish its identity.
It is a further object of this invention to provide such a transponder for which such broadcast rate is .~
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lZ1~36390 externally controllable.
It is a further object of this invention to.provide such a transponder which permits individual location of simultaneously broadcasting transponders on the same reply frequency.
It is a further object of this invention to provide ~ such a transponder apparatus which can réceive an j actlvation code ant transmit its reply code on the same frequency.
The invention results, in part, from the realization of a truly effective vehicle transponder that can detect encoded information, provide a reply code specific to the ,' transponder, discern the presence of a specific identification code and a broadcast.rate command in the ~, encoded informatlon, and determine the transmission period for the reply code based on the broadcast raee command.
Other and further ob~eccs will be explained hereinafter and are more fully delineated in the appended claims.
In summary, however, from its overall aspect, the invention embraces a method of tracking a computer-'; registered transponder equipped vehicle and the ~, "'~'i' ' $~
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~Z~3G390 like, upon the same being missing, that comprises, checking the registration of such vehicle to determine that it is computer liste'd as transponder-equipped; upon affirmative determination of such transponder equipment listing, initiating the broadcasting in an appropriate sector of a radio activation command signal carrying coded identification unique to said vehicle and its transponder; recelving said command signal at the vehicle transponder, decoding the identification and verifying that the same is the unique code of said vehicle and its transponder, and, if so, causing the transponder to become activated to transmit periodic vehicle reply signals including unique identification; receiving said periodic vehicle reply signals in a tracking vehicle and locking onto the same; thereafter, at the request of the tracking vehicle, modifying the said sector radio activation command signals to provlde increased-rate command signals to the vehicle transponder; and responding to the increased-rate co~mand signals at the vehicle transponder to increase the periodicity of the transmitted transponder vehicle 8ignals to facilitate tracking by the tracking v-hlcle.
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-:- - ~ . . :. -From other viewpoints, the invention also involves a novel transponder apparatus for use in identifying the presence of an object interrogated by broadcasted radio activation command signals on a predetermined RF carrier carrying coded identification unique to that object and its transponder, the apparatus having, in combination, means for receiving said command signal and for decoding the ldentificatlon and verifying that the same is the unlque code of said object and its transponder; means operable in the event of such verification, for activating the transponder to transmit periodic reply signals on the same carrier frequency and including unique identification thereupon; and means responsive to further command signals requesting a variation in the rate of such reply signals for thereupon transmitting the reply signals at such varied rate.
From still another aspect, the invention provides a transponder apparatus which detects encoded informacion, discerns the presence of its specific and unique identifi-cation code and a broadcast rate command in the encoded information, and transmits a reply code specific to the transponder, while determining the next time of trans-3~0 mission of the reply code for periodically repeating suchreply transmissions. In one construction, the transponder monitors RF command signals for predetermined encoded audio signal carried by the broadcast signal. The audio signal conveys encoded digital information using different audio frequency signals or tones, to define the informa-tion, which typically includes a broadcast rate command for the transponder replies and an identification code ~pecific and unique to that transponder (although in certain instances a universal identification code such as a universal test code may be substituted for the specific identification code). The transponder converts the digi-tal information lnto digital logic signals and, if the specific identification code is present, broadcasts a reply code, specific to the transponder, repeatedly at a rate determined by the externally controlled broadcast rate code command, which may be changed to vary the trans-ponder reply rate. ~utual interference with both recep-tion and transmission is avoided with the preferred single carrier frequency employed, by pseudorandomly varying the transmission period. A number of activated transmitters, moreover, can broadcast simultaneously on the same RF fre-:~ .
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quency as well as monitor that frequency for additionalcommands.
And, in another feature, the invention further pro-vides a transponder vehicle tracking apparatus having, in combination, direction-finding means for receiving activaeed vehicle transponder periodic radio reply signals carrying vehicle identification code information; signal -and microprocessor means for demodulating said identifica-tion code information and for alpha-numerically displaying the same; means also responsive to the last-named means for simultaneously displaying both the bearing from which the transponder reply signals are received and the signal strength thereof; and means for locking onto and displaying only radio reply signals of a selected vehicle transponder.
Mention should also be made of the feature of using non-volatile memory to remember the state of the transponder so that if electrical power should be removed after activation, when electrical power is restored to transponder it will continue to transmit reply code without need for re-activation.
~roferred and best =ode embodi=en~s ~nd appara~us ", , ..
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_9_ details are later explained.
The invention will now be described with reference to the accompanying drawi~gs, Fig. 1 of which is a syste~
diagram of the preferred vehicle location system application of the concepts of the invention;
Figs. 2 and 4 are bloc~ circuit diagrams of a transponder or transceiver apparatus particularly designed for use in the vehicles-to-be-tracked in the system of Fig. l;
Fig. 3 is an encoded infor~ation sequence useful with the system;
Fig. 5 is a flow chart of the operation of the receiving and transmitting functions of the transponder of I Figs. 2 and 4;
Figs. 6 and 7 are block circuit diagrams of a preferred vehicle tracking receiving and display systems for homing-in on the reply signals of the transponders of Figs. 1, 2 and 4; and Fig. 8 is a data flow diagram of the sector activation computer-controlled broadcast command system providing radio signals eo interrogate and activate the vehicle transponders of the invention.
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12~3~3~0 A descripeion, first, of the overall philosophy and methodo.logy underlying the total system operation of the invention in preferred form is in order, with reference to the Svstem diagram of Fig. 1.
Uhen a vehicle V (or V') equipped with the trans-ponder T (or T') of the present invention is lost, the owner reports that fact to the local police department which, in turn, reports to a state computer station system S. In tests in Massachusetts, this system, as later explained, is termed LEAPS. This information is sent, as a matter of course, from station S, as by telephone network or link L, to a master computer file, preferably maintained, for example, by the National Crime Information Center (NCIC), a part of the FBI in Washington, D. C., (or at other suitable computer facilities) and whereat it is intended. to have in storage (SVLS -- stolen vehicle location system), a list of the vehicle identification numbers of registered subscribers to the theft system of the invention. Every stolen car report that comes in, will be checked against the subscriber list (SVLS data base), and if a match is found, a computer message will be sent back at L to the originating station S, with a - :-.
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12~639(~
set of information that includes a unique activation codeand a unique reply code for the transponder of the stolen vehicle, and a descriDtion of the vehicle. This informa-tion, now a~ the compucer LEAPS) at location S, is used to cause a controlling computer (SV~S computer) to set up a transmission schedule and, as by microwave link M, initiating the transmitting of the activation code from a series of radio broadcasting transmitting antennas B (B'), operated sequentially or lf sufficently spaced, simultaneously or in slave fashion, thereby causing the stolen vehicle transponder, if in the area or section, to activate with a certain probability. The activator code is broadcast periodically (schematically shown at C) until a report is received that the car has been retrieved or until some predetermined time interval has been exceeded.
These activation command signals broadcast at C, have the activation code of the vehicle transponder, check-sum digits, and certain command bits that cause turn-on, turn-off and speed-up, as later explained.
As before stated, the frequency of the broadcast transmiteer~ is the same as that of every vehicle trans-ponder; namely, for example, a nationally assigned V~F
.
'~ ' , '' law-enforcement frequency. But each transponder T (T') transmits a digital coded response or reply of about a tenth of a second durat~on, periodically and preferably at pseudo random intervals, say, once every ten seconds, roughly. In accordance with a feature of the invention, however, if the transponder detects another transmission on the frequency, it waits until that message is completed and then commences its reply transmission.
A police or other tracking vehicle TR, appropriately equipped with a direction-finding antenna system A and a trac~ing receiver and display D, when within range of the missing vehicle, will display on an indicator panel the coded response of the vehicle transponder, received along schematic path(s) R (R'), a five-digit alpha-numeric code corresponding to the code being transmitted by the vehicle transponder T (T'). When the police officer sees that display at D, the officer calls into his radio dispatcher, via RD, who puts an inquiry at P into the state computer (LEAPS) and inquires as to the status of that code. If it turns out that this is a vehicle that is stolen or that ic is otherwise desired to track, then the sector broadcast transmitters B (B') will be activated to send out a .
12E~t~390 different transmission C distinguished from the first activation signals to vehicle transponders T (T') in that it represents a request to increase the periodicity or rate of vehicle transponder responses or replies. The second, step-up or speed-up reply request command signals C will have the same vehicle identification nûmber, it may or may not have the same check-sum bits as the first type activation command signals, but it will have a different code in the command section of the message, causing the speed-up, as opposed to just turn-on.
When the vehicle transponder receiver receives this increased rate command signal, the transponder circuits will cause the transmission of the coded reply or response message signal from the transponder vehicle to be accelerated to a faster rate of transmission, say about once per second, along R (R'), so that those in the track-ing vehicle TR, instead of seeing the coded number once every ten seconds on the display, will see it once every second or so to aid in homing-in. The transponder will stay in that speeded-up mode for a period of time, say 30 minutes, and then automatically return to the regular mode ., .
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~Z~6390 of transmitting once every ten seconds, the expectation being Ghat within a half hour, the vehicle ough~ tO have been recovered.
If recovery has not been made, the tracking vehicle can always ask for the speeded-up vehicle transponder reply command request to be broadcast again at B (B').
At the tracking vehicle TR, not only are vehicle transponder reply codes displayed, but a lock select or control (button, for example) is provided at D to cause the computer processor in the tracking device to display only signals with a particular reply code from a par-ticular vehicle transponder, to the exclusion of other vehicle transponder signals as from other stolen vehicles in the area. In addition to the reply code display, the . tracking vehicle installation is provided with a direction indlcator such as a circle of light-emitting diodes that gives relative bearing or direction of reception of the transponder signals. The direction-finding system at the tracking vehicle preferably employs four roof antennas A, later discussed in connection with the embodiment of Fig.
6, that are electronically phased to determine the incom-~ ing signal by determining the Doppler shift, as is well-'~:
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12~3~i390 known, and providing the bearing indication.
In addition to the bearing indication, a bar-graph indicator is further provided at D that shows relative signal strength and thus a rough indication of range.
This is important in tracking, particularly in urban environments where the signal can bounce off a building or other vehicles and trucks that may be close by. The signal that comes from the direction of the stolen vehicle wlll usually be the stronger; so that if the tracker sees the signal strength display in erratic mode, the direction of maximum signal strength is followed.
The tracking vehlcle personnel, as they home-in, thus know the relative dlrection, the relative signal strength and a complete description of the vehicle being sought;
and, of course, other information that may be pertinent such as whether the car may have been involved in an armed robbery or some other important aspect. After finding and securing the sought vehicle, the personnel of the tracking vehicle will repore that the car has been retrieved so that the system may cancel the stolen car report in the NCIC and other computer files. Again, in accordance with preferred features of the invention, this is also .
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121~639(~
automatically effected, with the software at NCIC checking and issuing a new set of command instruceions which causes the turn-off of the command sign~ls previously broadcasted in the search sector. Other aspects or preferred refine-ments in the best mode of practice of the system of the invention include the following. Messages that come in to the computer controlling the broadcast transmitters are queued up before being transmitted because it takes a certain amount of time for the trasmitter to build up to full intensity, which amount of time is of the same order of magnitude as the messages-to-be-sent. The sector broadcast transmitters will send out their activation signals and codes on a periodic bases, perhaps once an hour or so, as before indicated, until the vehicle is either recovered or a certain period of time has gone by, which may, for example, be set at a month.
From a practical viewpoint, it is important to have some way of checking out the eransponder system once it is installed in the car. This may be effected by an installation test unit, later described in connection with the functional or operational diagram of Fig. 5. This insea11ation cese unit is capab1e O e sending a signal to ", ~' -.
~2~;;390 the transponder receiver portion T-R~ which the trans-ponder recognizes as a signal coming from the test device and which causes the transmitter section T-T~ of the transponder T to go into a low power mode, in response also to another safeguard signal that it picks up on it's DC power line, simultaneously.
In this preferred nationwide cooperative system illustrated in Fig. 1, (though the invention is also useful for smaller sectors, states, group of states or other sector sub-divisions as well), thus, each vehicle transponder or transceiver assembly is part of a national (or at least wide-area) stolen vehicle location system, as above indicated, shown as preferably coordinated with the National Crime Information Center, NCIC.
When a vehicle such as automobile(s) V (V') is reported stolen, information such as the license is entered through terminals P at any of a number of terminals disposed throughout the area being monitored, such as in local police stations or other municipal build-ings, all such cooperating with the before-mentioned LE~PS
computer which has access to information as to the manufacturer's vehicle identification number, description, ., ~ ' ' :, .
.
, 1213~;390 etc. This is a procedure followed in recent testing of the invention in Massachuse~ts. The LE~PS computer interacts via L with the SVLS data base, to determine if the vehicle is equipped wi~h a vehicle transponder T
according to this invention. The vehicle identification number is sent through the federal communications tele-phone or other networking L to the NCIC computer in Washington, D.C., where, according to the preferred mode of the invention, once the vehicle is identified (from compari90n with stored data) as a subscriber equipped with such transponders, the SVLC software accesses the SVLS
data base at NCIC to determine the unique activation code for the vehicle V (V') and the unique reply code which that transponder will broadcast upon activation. The activation code and reply code information are returned automatically through network L to the LEAPS computer which engages the SVLS computer and as through microwave control link ~, relays the code information to the radio tranYmitter at B to broadcast an RF carrier command signal containing on its carrier frequency the vehicle activatiOn code and including the specific unique vehicle identification code and a command for the transponder to .`,~ ' :, .
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~Z86390 reply ac a particular rate.
Let it be assumed that vehicle transponders T and T', hidden within cars V and V', respectively, are both in range of sector activation transmitter B, as shown. Only transponder T, however, will respond to the unique identi-fication code broadcast along C by transmitting antenna B. Upon activation, transponder T then broadcasts its reply code unique to it which is then received at D by the tracking vehicles such as a police cruiser TR. The code name for car V i9 thus displayed on a console at D. The tracking officer relays this code name along radio link RD
to the police dispatcher, who accesses the LEAP and SVLS
computers at S to obtain a description of the vehicle V, which is then radioed back to cruiser TR so that the officer can visually identify the vehicle V.
As before stated, homing-in can be facilitated by step-up or increase of the periodicity of transponder reply signals as the tracking cruiser enters the vicinity of the stolen vehicle V. By requesting such speed-up via link RD, the SVLS will control the before-~entioned increased rate request, causing the signals broadcast at C
to command such step-up in transponder reply rate.
, ~2~363~
Turning, now, to details of preferred implemenea~ion of the various components of the system of the invention, a useful transponder or transceiver configuration T is illustra~ed in Fig. 2, wherein an antenna 1, hidden in the vehicle V (as inside the seat backs, dashboards, etc.), is connected to a switch 3, such as conventional PIN diodes or the like, for switching the antenna to the receiving or transmitting circuits of the apparatus at appropriate time8.
Assuming that the switch 3 is in the receiving func-tion, the antenna 1 is then connected to an RF amplifier and then a mixer so-labelled, which, with the mixing of a local oscillator (lst LØ), takes the carrier frequency of the activation command signals C broadcast by B (B') down to a first intermediate frequency, say from a specified VHF carrier (narrow-band FM audio FSK signal) to an intermediate frequency of 10.7MHz. This is filtered and then applied to demodulator, so-labelled, that basically extracts the audio from the signal. That audio comprises two tones, one of which corresponds to a logical "zero' and the other of which corresponds to a logical "one". The purpose of the modem 5 receiving these .
: ' . ' .' ' 3~30 filtered tones is to convert the tones into digital voltage levels, corresponding to the "zero" and "one".
The converted logic levels are applied to a microprocessor 5' which serves as a control device.
When the vehicle code has been identified, as later explained, and it is desired to reply or respond with nique vehicle code periodic transmitted signals, as before explained, the microprocessor 5' generates logical levels which it then feeds to the modem 5 to convert those logic levels back into tones which are fed into a modu-lator so-labelled, in the transmitter (bottom) portion of Fig. 2. The modulator modulates the transponder trans-mitter T-TX consisting of an oscillator, a frequency tripler to bring the frequency to that of the input com-mand signal carrier. The transmitter is a driver and a power amplifier (power amp), adapted to feed the trans-ponder antenna to transmit the reply signals R (Fig. 1) on the same carrier frequency as the broadcast activation command signals C, when the switch 3 connects to the power amplifier under the control (via 3') of the microprocessor 5'. A high-power switch (Hi-power), is also shown controlled by the microprocessor 5' to bypass the last-3'~0 named power amplification seage (power amp) so that a mode for low-power test and installation transmissions is pro-vided.
An e~ample of coded information originally carried by the broadcast command activation signals C as F~-modu-lation and received by the vehicle transponder T is shown in Fig. 3. The preamble I comprises initially sequential digital logic "ones" and "zeros" which allow modem 5, before mentioned, to synchronize with the signal. The next block II, labelled "Flag", indicates the commencement of the following data frame containing the information conveyed by the two audio tones (say, of 1200 and 1800 Hz frequency) representing logical "ones" and "zeros". When the signal C is intended solely for the transponder ~ of missing vehicle V, the transponder code III represents the unique digital address for transponder T. The rate com-mand portion IV is an activation command, a deactivation command, or a step-up transponder reply periodicitycommand represented by one or more values in binary form. Las~ly, the frame may further include conventional redundancy checks V, shown dotted, such as cyclic redundancy checks, ., , .
. . .
12~36390 vertical redundancy checks, or longitudinal redundancy checks which permit error correc~ion and detection of transceiver code III and rate command IV.
Using the code information of Fig. 3 as exemplary, the corresponding encoded information may be traced through the transponder circuit of Fig. 2, as follows.
When the FM-RF signal C having the preselected carrier frequency ls received, the same is demodulated, as before explalned, producing the carried audio slgnals represent-lng the desired digltal information. The modem 5 converts the audio slgnals lnto digltal slgnals, as prevlously ; stated, and microprocessor 5' recelves the digital infor-mation when the audio signal is, say,. in the range of 1100 ~ to 1900 Hz. The modem 5, such as, for example, Type 409 ; of MX-COM Inc., of Winston-Salem, North Carolina, outputs a logical "one" for one cycle of 1200 Hz, and a digital "zero" or one and one-half cycles of 1800 Hz in the above ; example. Microprocessor 5', such as, for example, Type MSM5840RS of OKI Semiconductor, Inc., Santa Clara, California, processes the encoded digital information as follows. A nonvolatile memory 7, such as an EEPROM
(electrically erasable programmable read-only memory) or , ~ other PROM cooperates with the microprocessor 5' and .~, .,~, ? ~
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~2~3~390 contains the specific vehicle transponder identification code, to be compared with the encoded digital information III, Fig. 3, and ehe matching transponder reply code. To conserve power, this memory 7 is provided with power only when retrieval of its information is required. In combin-ation with the feature that inter~ittent or periodic transponder reply signals are generated only upon command, as described, the transponder efficiently conserves power. The car battery +,- or other battery provides power at twelve volts to a power regulator 9 which main-tains a five-to-six-volt power outpout to the micropro-cessor 5'. A voltage level detection circuit 11 resets the microprocessor 5' when the voltage drops below a pre-determined voltage, thereby allowing it to complete routine housekeeping while sufficient power remains. As an example, the most recent rate command can thereby be stored in the nonvolatile memory 7 before power is totally lost.
For testing purposes, the microprocessor 5' may .
-.
12~i390 broadcast a test reply signal when a universal RF tese signal is received simultaneously with an electrical signal of predetermined special frequency on the unit's D.C. power supply (as detected by a power signal de~ection circuit 13). The special signal is of frequency high enough so that the impedance of battery +, - does not interfere with signal detection, and low enough so that a test signal does not create BF interference. The special electrical signal is required so that the test device cannot be used by an authorized person to locate cars equipped with the transponder of the invention.
Returning to the normal operation, when the proper identificatlon code is received, microprocessor 5' recalls lts specific reply code from the nonvolatile memory 7, stores lt in RAM, and submits the information to the modem 5 which converts the digitally encotet information back into an audio signal. As before explained, with antenna switch 3 dlsabllng connection to the receiving part (T-R~) of the transponter, the transmitter portion (T-TX) on activation of the transmit switch 15, under control from the microprocessor 5', transmits on the same carrier frequency the reply FM signals carrying the audio cote ''' , .
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3~0 reply signal; but only if the microprocessor 5' coneroll-ing antenna and transceiver switches 3 and 15, does no e receive indication from modem 5 that ~he receiver portion is still receiving a transmission on the carrier frequency; otherwise, the control signal awaits absence of such carrier frequency. As before stated, the use of the non-volatile memory enables the transponder to continue replying after an interruption in replying caused by power failure.
The microprocessor 5' includes an operation for lnterpretlng the broadcast rate command when received with the iden~ification code specific to a particular vehicle transponder T. A schematic implementation of this part of the operation in hardware form is shown in Fig. 4, such being considered as effectively incorporated in the pro-cessor 5' of Fig. 2. In actual practice, of course, con-ventlonal software control will be provided, the hardware explanation, however, more facilely describing the opera-tional functions. Specific identification (ID) code comparator 17 matches the received identification code with the identification code stored in RA~, after it is accessed fro= the notvo1ati1e =emory 7 oi Fig. Z. Ii the ~ . _ ~2~3~0 identification codes match, the broadcast rate command is provided to rate i~terpreter circuit 19 which selects a reply broadcast rate at s~itch SW. If the rate command is "00", Fig. 4, for e~ample, pseudorandom generation circuit 21 is accessed, this circuit periodically receiving a pulse from a clock 23 and delaying signalling trans-mitter-enable circuit 25 by an additional amount of time represented by a pseudorandomly generated number. For example, clock 23 may provide a pulse every 8 seconds, and circuit 21 may generate an additional delay period of O to 4 seconds, resulting in the about once per ten second rate of periodic reply signals as the enable circuit 25 is signalled to command transmission of the replies.
When a step-up or increased reply rate command is received ("01"), such as after a police cruiser nears the stolen vehicle, a step-up clock 27 is accessed, as by switch SW effectively moving to the position shown in Fig. 4, the clock 27 generating a pulse at short, regular intervals, such as once every second, which triggers enable circuit 25 to continue transponder transmission at that rate and also steps up the pseudo random circuit.
After a predetermined period of time, clock 27 , :
-~Z~363~0 signals rate interpreter circuit 19 through line 21' to return to the normal broadcast rate (Sw position "01"), whereupon normal reply activation rate continues until a deactivation com~and "02" is received, at which eime switch SW contacts ground to cease transmissions.
One suitable operation logic for the transponder T is shown in Fig. 5. In receiver T-RX, represented by opera-tional step 3~, the frequency of the incoming carrier signals C is monitored, and unless received, the monitor-ing continues at step 31. If the received carrier fre-quency is valid and the audio signal thereupon is within the preselected frequency range, step 33, the encoded information enters the modem 5 and microprocessor 5 t for processing (RX-AUDIO 11, Fig. 2).
The transponder may include a testing feature, indicated in dotted lines as step 35, where an RF test signal carrying a test code within the correct audio range may trigger the transponder T-TX to b~oadcast a test reply signal, step 37. For test step 35 to be satisfied, a pre-selected signal detection circuit 13 of Fig. 2, earlier described must detect the appropriate signal on the D.C.
power line.
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~29-Lf the testing feature or the criteria for entering its subroutine are not present, the specific transponder code for the vehicle V is recalled from memory in step 39 and compared to the converted audio tone digital inror-mation on the incoming signal. When the specific trans-ponder code is not present, monitoring continues, step 31;
but if the specific transponder code is discerned, the rate command is relayed, line 61, and is distinguished within the trànsmission command procedure 41 to determine transmission of the reply code by the transponder trans-mitting portion T-TX. When a deactivation command is present from the broadcast signal C, step 43, the tran~ponder T ceases broadcasting replies, 45, and then, as indicated by line 59, resumes monitoring, step 31.
The presence of the transponder activation command of broadcast signal C is determined in step 51, and of the reply rate step-up request command, at 47. The trans-ponder ls activated to reply, or it receives the step-up rate command to replay at a greater periodic rate. The step-up command, as before explained, may remain in effect until a deactivation command is received or until a pre-determined period of time has elapsed.
' .
" ~ ' - ' ' --1Z~639`~:) When the activation command is received, a broad-cast-enable is generated pseudorandomly, step 43, at an average rate which is slower than the step-up rate; for e~ample, "enables" may be generated in step 49 once every second, as before discussed, whereas the normal reply "enable" may be generated, step 53, once every 10 seconds or so, including plus or minus a random number, thereby minimizing the chance of overlap with the reply broadcasts of other activated transponders. Preferably, after each new rate command is received, it is stored in nonvolatile memory, shown dotted at 55, and corresponding to the memory 7 of Fig. 2. Conventional error correction and detection can be performed on the incoming data in steps 39 and 41 by means of well-known vertical, longitudinal, and cyclic redundancy checks, as previously mentioned.
It is now in order to examine the necessary type of circuits for the tracking vehicle receiver equipment TR, Fig. 1, a preferred form of which is illustrated in Fig.
6. The tracking receiver has two main parts; a radio-receiving, power and processing portion; and a display, portion D. The receiving pcrtion comprises an RF summer 2 that multiplexes the inputs from four antennae of the i286390 tracking vehicle direction - finding antenna system A
(Fig. 1): J 4, J5, J6, and J7. The sum of the four inputs generates the signal from which the user is able to determine the direction of either a vehicle transponder T
being tracked or any device that may be jamming the vehiclettransponder. The summer output contains the very high frequency carrier signal of the vehicle transponder coded reply with response signals and is fed to a narrow band FM receiver 4 which "strips off" the infor-mation-carrying signals in the audio range (1200 and 1800Hz and the Doppler modulation frequency from the direction-finding, such as 422 ~z), and supplies that demodulated audio signal to the tracker's microprocessor and signal processor 6. The microprocessor portion decodes the reply code of the vehicle being tracked and the signal processor determines the car's direction, as later discussed.
The receiver also provides the signal strength level that indicaees the stolen car's distance from the tracking vehicle, as also hereinafter more fully explained.
3~0 The power for the eracking receiver, which may range from 11.5 to 14.5 volts, is supplied by the police or other tracking vehicle in which the device is mounted.
The power supply ? and SP cloc~ and filter circuit board 10 supplies all the power necessary for the functioning of the tracking device, contains the master clock for the signal processor 6, and does some preliminary filtering of the signal for the signal processor.
The signal processor board 6 has two functional parts: a control voltage waveform generator and an audio signal processor, The control voltage waveform generator portion provides the signals (VCA, VCB, VCC, VCD) that are necessary for the RF summer 2 to multiplex s~oothly from one of the four antenna signals to the next, in conventional fashion. These four signals, which are all identical, are shifted 90 degrees according to a precise curve calculated from PROMs contained on the board. The audio signal processor portion, on the other hand, takes the filter signal from the power supply board and performs additional filtering, which serves to make apparent the before-mentioned Doppler shift that indicates the direc-tion of the car being tracked.
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' - ', - ~ ' : ' : ' ~2~3~0 The primary function of the logic/demodulating board 8 is to take the signal strength from the receiver 4 and convert it into digital form. It performs that function by de~odulating the received signal into a stream of O and 1 bits that contain both the reply code of the car being tracked and a number of error detection and correction bits. The logic board also reads and controls the syste~
display D.
That display/control portion D, which may be mounted on the dashboard of the trac~ing police car, contains two boards: one for displays (Dl) and one for the display logic (D2) -The display D2, more particularly delineated in Fig.
7, consists of an array of LEDs, arranged in a circle 12 and representing compass points, as well as a central LED
12' that serves as a point of reference (particularly at night) for those around the circle's edge. There is also a bar graph BG with LEDs that indicate relative signal strength by the height of the lighted display. Another LED 12" placed next to the bar graph BG indicates wheCher the bar graph display is on the local or distant display range.
..
.
~2~;3~) At the upper center of the display is a 5-charac~er alphanumeric display CD that shows the reply code of the car being tracked.
There is also a lock-unlock switch 14 that enables the user to lock onto a particular reply code. When the switch is not in the lock position, each code from all of a multiplicity of vehicle transponders within range of the tracking vehicle shows for one second.
The preferred alphanumeric display at CD is effected from data clocked from the microprocessor 8 (G~, Fig. 7) into a pair of 8-blt shift registers SR, the first bits controlling which of the LED dot-matrix display unit of CD
are used to display a given character ~left), and the following comprise the code for a given character, so as to produce an alphanumeri.c display containing the unique code or serial number of the vehicle transponder which is ~ending the reply signals R to the tracking vehicle. In a practical implementation, a thirty-five bit shift register SR', controlled by clock C', which is in turn supplied with control outputs G1 - G3 from the microprocessor logic demodulator 8, receives information for the compass point : ' ~, .
~ :, ~' : ''' l'Z~63~t0 L~D display 12> the on/off (po~er) control LED 12', the local/distance LED 12' and the bar graph BG -- all as clocked sequentially into the shift register SR'. On the 36th clock pulse from the clock C', the daea is laeched and outputted to the appropriate LED's.
In summary, when the tracking vehicle equipment TR is turned on, but is not receiving a signal, the direction lndicator display 12 (Fig. 7) is blank, the signal strength indicator display BG reads O, and the code dis-play C~ is blank. In this mode, any received vehicle transponder signal R of proper carrier frequency will trigger the TR. When such a signal is received, the tracking indicator 12 illuminates to show the bearing of the received signal and the signal strength indicator BG
indicates a relative signal strength value.
If the received signal is a coded vehicle transponder signal, a five character identifier for that vehicle transponder appears in the digital display CD. As the tracking vehicle approaches the vehicle, the sig,nal strength increases. If the distance is increasing, the signal strength will decrease. In urban areas and other places where there are standing waves and reflections, the signal strength may not give a reliable indication of .. , ~ `', ~ ' '' ' ` ~ .
lZ~63~3 relative distance at all times, but provides homing-in assistance eventually. In case more than one vehicle transponder is being received, the loc~ switch 14 can be operated when the desired vehicle's code identifier is displayed at CD. This causes the TR to trac~ only that specified vehicle. When, moreover, the TR displays a normal message from a vehicle transponder, the center LED
12' of the direction display is illuminated.
Finally, the data flow operation for the sector activation transmitter(s) B (B', etc.), Fig. 1, will now be addressed, with reference to Fig. 8 and with common letter part identification with Fig. 1, and with the assumption that the operation will be a national system with NCIC reports on stolen vehicles which go into the national vehicle ~ile DG at NCIC. The stolen vehicle report is entered by local police and dispatcher terminals P (E6, E1) to the state LEAPS computer (P7) which communi-cates with NCIC along lines ~ as discussed in connection with Fig. 1. With the implementation of the present invention, NCIC also would store from data entries E8 and master file up-dating P10, the master file D4 of vehicles equipped with the transponders of the invention, labelled ."
~ -lZ863'~0 SVLS data base in Fig. 1. If the reported vehicle was equipped with the invention, NCIC would send back at L not only their normal reply, but an extra message giving the transponder activation and reply codes of the repor~ed vehicle so that this vehicle transponder may be activated for tracking. The state police computer (LEAPS of Fig. 1) would pass that request to the SVLS computer of Figs. 1 and 8 linked up with the terminals of all the police agencies in the state and receiving (from P7 to P5) request for P5 to process such activation request (or a deactivation when the police recover a stolen vehicle and report such). When P5 receives such request, three things happen. ~irst of all, the request is logged at D5. Then an entry is put into a queue D7 for immediate action, with such queue being serviced, say, one entry every 15 seconds either to broadcast activation command signal C or to place the request into the periodic action queue D3. Such activation signals will be broadcast unless there are others waiting, ln which case, it has to wait its turn.
Thirdly, the request is received in an active file D1 which consists of all business relating to activations and de-actlvations that are currently ln process. An , , . . ,:: ' ' :. : . . . .
: , . : . . ~ .: :
.: ' 12~363~0 activation request g~es into ~he file Dl for, say, 30 days, so that over the ne~t month, activation command signals will be broadcasted. Deactivations are handled the same way, although the time limit may be only 24 hours.
Function P2 removes records from the active file Dl older than 30 days if they are not active; and other than 24 hours, if they are not active, logging its activity.
P6, which represents the broadcaster control signals developed by SVLS Computer, services the immediate action queue D7 once every 15 seconds as earlier mentioned, and causes the periodic sector broadcast command signals C to be transmitted from a local transmitter E3 and/or slave transmitters E4 (B and B' in Fig. 1). The P4 (develop action queues functio~) o-perates every hour to renew the active file Dl and a local file D2, later described, and an hours worth of broadcasting material. Old records may be removed from the local file at P3.
The below-mentioned local file D2 contains data which comes rom Pl (process local transactions) originating at the console El of the SV~S computer, containing a file of vehicle tran-ponders which have been entered locally as .
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for test and other special purposes. The console El itself is protected by a system of passwords (D12, Dll) and daee and time eneries (310) so that unauthorized com-mands cannot be entered. Conventional print-out may be available as at E5.
While necessary and designed particularly for the purposes of the present invention, the transponder apparatus of the invention may also more generally be employed where transponder or transceiver operation is useful with a reply code specific or unique to that transponder and which it broadcasts at a variable and externally-controllable or - commanded rate. The identlfication of vehicles or, more generally, objects so-equipped, for example, is of utility in some apparatus, altogether apart from tracking the same.
Though the invention has been described, moreover, in its preferred mode of operation as a national system, clearly, as before stated, the vehicle identification code material and the like may be stored and supplied within the state or other locale without cooperation with NCIC.
Other well-known circuits and apparatus and conven-tionally derived software for performing the stated func-.. . ' .
: :
lZI 3~ii390 tions than those shown may also be used, as may certain functions be omieted if not desired; and while specified features of the invention may be shown in some drawings and not others, this is for convenience and clarity of description only, it being understood that each feature may be combined with any or all of the other features of the invention. Similarly the particular selection of frequency reply rates, type of encoding, audio tone range, etc., types of tracking, communication and broadcasting antennas, etc., are illustrative of what is believed to be preferred and what has been successfully experimentally tested; but further modifications will occur to those skilled in this art, and such are considered to fall with-in the spirit and scope of the invention as defined in the appended claims.
Claims (27)
1. A method of tracking a computer-registered transponder-equipped vehicle and the like, upon the same being missing, that comprises, checking the registration of such vehicle to determine that it is computer listed as transponder-equipped; upon affirmative deter-mination of such transponder equipment listing, initiating the broadcasting in a selected sector of a radio activation command signal carrying coded identification unique to said vehicle and its transponder;
receiving said command signal at the vehicle transponder, decoding the identification and verifying that the same is the unique code of said vehicle and its transponder, and, if so, causing the transponder to become activated to transmit periodic vehicle reply signals including unique identification; receiving said periodic vehicle reply signals in a tracking vehicle and locking onto the same;
thereafter, at the request of the tracking vehicle, modifying the radio activation command signals to provide increased-rate command signals to the vehicle transponder; and responding to the increased-rate command signals at the vehicle trans-ponder to increase the periodicity of the transmitted transponder vehicle signals to facilitate tracking by the tracking vehicle.
receiving said command signal at the vehicle transponder, decoding the identification and verifying that the same is the unique code of said vehicle and its transponder, and, if so, causing the transponder to become activated to transmit periodic vehicle reply signals including unique identification; receiving said periodic vehicle reply signals in a tracking vehicle and locking onto the same;
thereafter, at the request of the tracking vehicle, modifying the radio activation command signals to provide increased-rate command signals to the vehicle transponder; and responding to the increased-rate command signals at the vehicle trans-ponder to increase the periodicity of the transmitted transponder vehicle signals to facilitate tracking by the tracking vehicle.
2. A method as claimed in claim 1 and in which the radio activation command signals and the transponder transmitted signals are effected on a common carrier frequency, sequentially shared.
3. A method as claimed in claim 2 and in which prior to the transponder transmission activa-tion, the presence of existing transmissions on said carrier frequency is monitored, and only upon absence of the same does the trans-ponder commence transmitting its signals.
4. A method as claimed in claim 3 and in which the transponder transmitted reply signals are periodic with a pseudo-random spacing to pre-vent interference with other transponder transmissions.
5. A method as claimed in claim 4 and in which the periodicity of said transponder transmitted reply signals is adjusted to about one each ten seconds, and the said increased periodicity is about one per second.
6. A method as claimed in claim 1 and in which, from a multiplicity of such transponder signals received by the tracking vehicle, the same selects and displays only the signal from the particular vehicle-to-be-tracked.
7. A method as claimed in claim 1 and in which, upon the reporting of the recovery of the missing vehicle, the steps are performed of deactivating the recovered vehicle transponder reply signal transmissions and terminating the broadcasting of said activation command signal carrying coded information unique to the recovered vehicle.
8. A method as claimed in claim 2 and in which false and spurious activating command signals are discriminated from the broadcast command signals.
9. A system for tracking computer-registered transponder-equipped vehicles and the like, upon the same being reported missing, having, in combination, means for initiating the broadcasting in a selected sector of a radio activation command signal carrying coded identification unique to the missing vehicle and its transponder; means contained within said missing vehicle transponder for receiving said command signal and for decod-ing the identification and verifying that the same is the unique code of said missing vehicle and its transponder; means at the transponder, operable upon such verifying, for thereupon causing the transponder to become activated to transmit periodic vehicle reply signals including unique identifica-tion; a tracking vehicle including receiving means for receiving periodic vehicle signals and lock-ing onto the same; means operable at said tracking vehicle for requesting the modifying of the radio activation command signals to provide increased-rate command signals to the vehicle transponder; and means at said transponder for responding to the increased-rate command signals to increase the periodicity of the transmitted vehicle reply signals to facilitate tracking by the tracking vehicle.
10. A system as claimed in claim 9 and in which means is provided for the radio activation command signals and the transponder trans-mitted signals to be transmitted on a common carrier frequency, sequentially shared.
11. A system as claimed in claim 9 and in which means comprising non-volatile memory is provided for enabling transponder replies interrupted by power failure to resume upon power restoration.
12. A system as claimed in claim 9 and in which means is provided for automatically terminating the increased-rate command signal after a predetermined interval of time, while restoring the broadcasting of the first-named activation command signal.
13. A method of locating a transponder-equipped object that comprises, initiating the broadcasting in a selected sector of a radio activation command signal carrying coded identification unique to said object and its transponder; receiving said command signal at the object transponder, decoding the identification and verifying that the same is the unique code of said object and its transponder and, if so, causing the transponder to become activated to transmit periodic reply signals including unique identification, modifying the said sector radio activation command signals to provide increased-rate command signals to the object transponder; and responding to the increased-rate command signals at the object transponder to increase the periodicity of its transmitted reply signals.
14. Transponder apparatus for use in identifying the presence of an object interrogated by broadcasted of an activation command signals on a predetermined RF carrier carrying coded identification unique to that object and its transponder, the apparatus having, in com-bination, means for receiving said command signal and for decoding the identification and verifying that the same is the unique code of said object and its transponder;
means operable in the event of such verification, for activating the transponder to transmit periodic reply signals on the same carrier frequency and including unique identification thereupon; and means responsive to further command signals requesting variation in the rate of such reply signals for thereupon transmitting the reply signals at such varied rate.
means operable in the event of such verification, for activating the transponder to transmit periodic reply signals on the same carrier frequency and including unique identification thereupon; and means responsive to further command signals requesting variation in the rate of such reply signals for thereupon transmitting the reply signals at such varied rate.
15. Transponder apparatus as claimed in claim 14 and in which means is provided operable prior to the transmitting of said periodic reply signals to insure the absence of other transmissions on said carrier frequency before commencing the transmission of said reply signals.
16. Transponder apparatus as claimed in claim 14 and in which said unique code is contained as audio signals modulated upon the said carrier of the command signal, and the said transponder verifying means comprises means for converting the audio signals to digital signals and comparing the same with stored digital signals representing said unique code.
17. Transponder apparatus as claimed in claim 16 and in which, upon said activation of the transponder, digital code signals represent-ing unique identification to be transmitted in the transponder periodic reply signals are converted to audio signals and are transmitted as modulation of the carrier of the reply signals.
18. A transponder for identifying and assisting location of an object, comprising, means for detecting encoded information; means for discerning the presence of its own identification code in said encoded information; storage means for providing a reply code specific to the transponder; transmission command means, responsive to said means for discerning, for distinguishing a broadcast rate command in said encoded information and for determining the period of transmission of said reply code; and means, responsive to said storage means and said transmission command means, for periodically transmitting said reply code.
19. A transponder as claimed in claim 18 and in which means is provided for psuedo-randomly varying the periodicity of the transmitted replies.
20. A transponder as claimed in claim 18 and in which said transmission command means includes transmission periodicity step-up means for recognizing a step-up command in said broadcast rate command and, in response thereto, for producing a shortened transmission period.
21. A transponder as claimed in claim 18 and in which said transmission command means includes deactivation means for recognizing a deactivation command in said broadcast rate command and, in response thereto, for ceasing further transmissions.
22. A transponder as claimed in claim 18 and further including means for sensing a transponder test code in said encoded information, and means responsive to said means for sensing for broadcasting a test reply signal.
23. A transponder as claimed in claim 22 and in which said means for sensing senses both a first test code in said encoded information and a second test code provided through a physical connection to the transponder.
24. A transponder for identifying and assisting location of an object, comprising: receiver means for monitoring an RF signal and demodulating it to recover a carried audio signal; means for converting said audio signal into digital logical ones when said audio signal is modulated at a first frequency and into digital logical zeros when said audio signal is modulated at a second frequency to obtain digitally encoded information; means for discerning the presence of its own idenification code in said encoded information; means for pro-viding, digital reply code specific to the transponder; transmission cmmand means for distinguishing a broadcast rate command in said encoded information and for determining the period of transmission of said reply code modulating means for converting said digital reply code into reply code audio signals; and transmitter means, responsive to said transmission command means, for periodically broadcasting said reply audio signals upon an RF signal.
25. A transponder as claimed in claim 24 and in which said transmission command means includes means for generating a random transmission period and further includes activation means for recognizing an activation command in said broadcast rate command and, in response thereto, for enabling said means for generating.
26. A transponder as claimed in claim 24 and in which both RF signals are of the same carrier frequency.
27. A system as claimed in claim 9 and in which the said tracking vehicle receiving means comprises direction-finding means for receiving the transmitted vehicle trans-ponder reply signals carrying code information as to said unique identifica-tion; signal-and micro-processor means for demodulating such identification code information and for alpha-numerically displaying the same; means also responsive to the last-named means for simultaneously displaying both the bearing from which the transponder reply signals are received and the signal strength thereof; and means for locking onto and displaying only the radio reply signals of a selected vehicle transponder.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000615740A CA1333635C (en) | 1986-03-31 | 1990-05-22 | Transponder vehicle tracking apparatus |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/847,152 US4818998A (en) | 1986-03-31 | 1986-03-31 | Method of and system and apparatus for locating and/or tracking stolen or missing vehicles and the like |
| US847,152 | 1992-03-05 |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000615740A Division CA1333635C (en) | 1986-03-31 | 1990-05-22 | Transponder vehicle tracking apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1286390C true CA1286390C (en) | 1991-07-16 |
Family
ID=25299902
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000533481A Expired - Lifetime CA1286390C (en) | 1986-03-31 | 1987-03-31 | Method of and system and apparatus for locating and/or tracking stolen or missing vehicles and the like |
Country Status (10)
| Country | Link |
|---|---|
| US (1) | US4818998A (en) |
| EP (1) | EP0245555B1 (en) |
| JP (1) | JPS62277579A (en) |
| AT (1) | ATE76201T1 (en) |
| BR (1) | BR8701433A (en) |
| CA (1) | CA1286390C (en) |
| DE (1) | DE3685328D1 (en) |
| ES (1) | ES2007038A6 (en) |
| HK (1) | HK42194A (en) |
| MX (1) | MX166803B (en) |
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-
1986
- 1986-03-31 US US06/847,152 patent/US4818998A/en not_active Expired - Lifetime
- 1986-08-22 DE DE8686306527T patent/DE3685328D1/en not_active Expired - Fee Related
- 1986-08-22 EP EP86306527A patent/EP0245555B1/en not_active Expired - Lifetime
- 1986-08-22 AT AT86306527T patent/ATE76201T1/en not_active IP Right Cessation
-
1987
- 1987-03-26 MX MX005745A patent/MX166803B/en unknown
- 1987-03-27 JP JP62073944A patent/JPS62277579A/en active Granted
- 1987-03-30 BR BR8701433A patent/BR8701433A/en not_active IP Right Cessation
- 1987-03-31 ES ES8700923A patent/ES2007038A6/en not_active Expired
- 1987-03-31 CA CA000533481A patent/CA1286390C/en not_active Expired - Lifetime
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1994
- 1994-05-05 HK HK42194A patent/HK42194A/en not_active IP Right Cessation
Also Published As
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|---|---|
| US4818998A (en) | 1989-04-04 |
| EP0245555A1 (en) | 1987-11-19 |
| EP0245555B1 (en) | 1992-05-13 |
| HK42194A (en) | 1994-05-13 |
| ATE76201T1 (en) | 1992-05-15 |
| DE3685328D1 (en) | 1992-06-17 |
| JPH0562957B2 (en) | 1993-09-09 |
| ES2007038A6 (en) | 1989-06-01 |
| BR8701433A (en) | 1987-12-29 |
| MX166803B (en) | 1993-02-08 |
| JPS62277579A (en) | 1987-12-02 |
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