Electronically programmable remote control for vehicle security system

Claims

What is claimed is:

1. An electronically programmable remote control vehicle security system, comprising:

a precoded portable hand-held transmitter comprising means for generating and transmitting a predetermined fixed, digitally encoded, radio frequency, receiver-responsive signal representative of a predetermined fixed transmitter code, and actuating means for actuating said generating and transmitting means so that said signal is automatically generated and transmitted upon actuation;

vehicle antitheft means;

a system control unit disposed within said vehicle, comprising:

(i) receiving means operable during a system program mode and a system operating-receiving mode for receiving said transmitted encoded signal and generating an electrical signal representative of the encoded signal;

(ii) a digital memory for storing data representative of signature code signals;

(iii) programming means for recording in said digital memory received signals for arming or disarming said vehicle antitheft means, said means activated only during said system program mode for automatically storing in said memory received signals representative of said predetermined transmitter code as a signature control signal for arming or disarming said vehicle antitheft means; further characterized in that said program mode is automatically terminated after a predetermined time delay from receipt of the last transmitted encoded signal during said program mode;

(iv) operating means activated during said operating-receiving mode for comparing received electrical signals with said signature control signal stored in said memory means to determine if said electrical signals correspond to said recorded signature code signal, and means for arming or disarming said vehicle antitheft means in response to received signals corresponding to said signature code signal stored in said memory; further characterized in that said system control unit comprises a user-accessible switch disposed in said vehicle, and said access control unit is responsive to the position of said switch for entering said program mode; and

wherein said transmitter and said receiving means cooperate to form a one-way radio frequency signal transmission link for communicating signals only from said transmitter to said receiving means, said transmission link being employed by said system during said programming mode for transmitting said encoded signals from said transmitter to said access control unit to be stored in said memory as said code signals, said link further employed during said operating receiving mode for transmitting said encoded signals from said transmitter to said control unit.

2. An electronically programmable remote control vehicle security system, comprising:

a precoded portable hand-held transmitter comprising means for generating and transmitting a predetermined fixed, digitally encoded, radio frequency, receiver-responsive signal representative of a predetermined fixed transmitter code, and actuating means for actuating said generating and transmitting means so that said signal is automatically generated and transmitted upon actuation; wherein said transmitter is suitably encoded with said predetermined transmitter code by the manufacturer thereof so that the system user is not required to encode said transmitter;

vehicle antitheft means;

a system control unit disposed within said vehicle, comprising:

(i) receiving means operable during a system program mode and a system operating-receiving mode for receiving said transmitted encoded signal and generating an electrical signal representative of the encoded signal;

(ii) a digital memory for storing data representative of signature code signals;

(iii) programming means for recording in said digital memory received signals for arming or disarming said vehicle antitheft means, said means activated only during said system program mode for automatically storing in said memory received signals representative of said predetermined transmitter code as a signature control signal for arming or disarming said vehicle antitheft means;

(iv) operating means activated during said operating-receiving mode for comparing received electrical signals with said signature control signal stored in said memory means to determine if said electrical signals correspond to said recorded signature code signal, and means for arming or disarming said vehicle antitheft means in response to received signals corresponding to said signature code signal stored in said memory; and

wherein said transmitter and said receiving means cooperate to form a one-way radio frequency signal transmission link for communicating signals only from said transmitter to said receiving means, said transmission link being employed by said system during said programming mode for transmitting said encoded signals from said transmitter to said access control unit to be stored in said memory as said code signals, said link further employed during said operating receiving mode for transmitting said encoded signals from said transmitter to said control unit.

3. An electronically programmable remote control vehicle security system, in which a receiver and a control unit therefor are operable upon receipt of a proper transmitted encoded signal from any of a plurality of transmitters to arm or disarm said vehicle security system, said system comprising:

at least one first transmitter capable of transmitting a first receiver responsive, radio frequency, digitally encoded signal comprising an N-bit digital code word for arming and disarming said system, said transmitter comprising actuating means for actuating said transmitting of said signal so that said first signal is automatically transmitted upon actuation;

at least one second transmitter capable of generating and transmitting a second receiver responsive, radio frequency, digitally encoded signal comprising an M-bit digital code word for arming and disarming said system, said second transmitter comprising actuating means for actuating said transmitting of said second signal so that said second signal is automatically transmitted upon actuation;

wherein N and M are each integer values and N need not equal M;

vehicle antitheft means;

a receiver located in said vehicle and responsive to the transmitted radio frequency encoded signals during a system programming mode and a system operating-receiving mode for generating electrical signals corresponding to each of the respectively encoded signals;

said receiver and said first and second transmitters comprising at least first and second one-way radio frequency signal transmission links for communicating signals only from said first or second transmitters to said receiver during said system programming and system operating-receiving modes; and

a control unit operatively associated with the receiver, said control unit comprising:

(i) means for decoding said electrical signals to generate respective decoded digital signals representative of said N-bit code word and said M-bit code word;

(ii) a digital memory for storing said N and M-bit code words;

(iii) means operable in said system program mode for automatically recording in said digital memory said respective decoded digital signals received and decoded during said program mode as first and second signature code signals representative of said N-bit code word and said M-bit code word;

(iv) means activated during an operating-receiving mode for comparing received and decoded signals to said first and second signature code signals which have been previously recorded during said program mode to determine if said decoded digital signals correspond to either of the recorded signature code signals and thereby represent valid signals for arming or disarming said vehicle antitheft means; further

characterized in that the system is user programmable such that the user of any transmitter may initially record the encoded signal from that transmitter as a signature code signal in the control unit by simple actuation of the transmitter when the system is in said program mode for recording signature control signals for arming or disarming said vehicle antitheft means, thereafter only requiring the transmission of the encoded signal from the transmitter for recording as a valid signature code signal, and whereby said signature control signal is automatically recorded in said digital memory; further

characterized in that said system is provided with a switch disposed in said vehicle to put the receiver in the program mode for recording said arming/disarming signature control words; and further characterized in that said system program mode is automatically terminated after a pre-established time delay from receipt of the last transmitted encoded signal during said program mode.

4. An electronically programmable remote control vehicle security system, in which a receiver and a control unit therefore are operable upon receipt of a proper transmitted encoded signal from any of a plurality of transmitters to arm or disarm said vehicle security system, said system comprising:

at least one first transmitter capable of transmitting a first receiver responsive, radio frequency, digitally encoded signal comprising an N-bit digital code word for arming and disarming said system, said transmitter comprising actuating means for actuating said transmitting of said signal so that said first signal is automatically transmitted upon actuation;

at least one second transmitter capable of generating and transmitting a second receiver responsive, radio frequency, digitally encoded signal comprising an M-bit digital code word for arming and disarming said system, said second transmitter comprising actuating means for actuating said transmitting of said second signals so that said first signal is automatically transmitted upon actuation;

wherein N and M are each integer values and N need not equal M;

vehicle antitheft means;

a receiver located in said vehicle and responsive to the transmitted radio frequency encoded signals during a system programming mode and a system operating-receiving mode for generating electrical signals corresponding to each of the respectively encoded signals;

said receiver and said first and second transmitters comprising at least first and second one-way radio frequency signal transmission links for communicating signals only from said first or second transmitters to said receiver during said system programming and system operating-receiving modes; and

a control unit operatively associated with the receiver, said control unit comprising:

(i) means for decoding said electrical signals to generate respective decoded digital signals representative of said N-bit code word and said M-bit code word;

(ii) a digital memory for storing said N and M-bit code words;

(iii) means operable in said system program mode for automatically recording in said digital memory said respective decoded digital signals received and decoded during said program mode as first and second signature code signals representative of said N-bit code word and said M-bit code word;

(iv) means activated during an operating-receiving mode for comparing received and decoded signals to said first and second signature code signals which have been previously recorded during said program mode to determine if said decoded digital signals correspond to either of the recorded signature code signals and thereby represent valid signals for arming or disarming said vehicle antitheft means; and wherein said first and second transmitters are respectively suitably encoded with said N-bit and said M-bit digital codes by the respective manufacturer thereof so that the system user is not required to encode said respective transmitters.

5. A vehicle security system in which a control unit is responsive to receipt of a proper transmitted encoded radio frequency signal from a transmitter to arm or disarm said system, comprising:

vehicle antitheft means, said means comprising a vehicle ignition disabling means;

a portable hand-held transmitter comprising means for generating and transmitting a predetermined fixed digitally encoded, radio frequency, receiver-responsive signal representative of a predetermined transmitter code; and

a control unit located within said vehicle, comprising:

(i) radio frequency signal receiving means operable during said program mode and during said system operating-receiving mode for receiving said transmitted encoded signal and generating an electrical signal representative of the encoded signal;

(ii) a digital memory for storing signature code signals;

(iii) programming means for recording in said digital memory received signals for arming or disarming said vehicle antitheft means, said means activated only during a system program mode for automatically storing in said memory said electrical signals representative of said radio frequency, receiver-responsive received signals representative of said predetermined transmitter code as a signature code signal for arming or disarming said vehicle antitheft means; and

(iv) operating means activated during an operating-receiving mode for comparing received electrical signals with said signature code signal stored in said memory means to determine if said electrical signals correspond to said recorded signature code signal and for arming or disarming said antitheft means if said electrical signals correspond to said recorded signature code signal, wherein said transmitter and said receiver means cooperate to form a one-way radio frequency signal transmission link for communicating signals only from said transmitter to said receiving means, said transmission link being employed by said system during said programming mode for transmitting said signal representative of said transmitter code to said access control unit to be stored in said memory means as signature code signals, said link further employed during said operating-receiving mode for transmitting said encoded signal from said transmitter to said access control unit; wherein said control unit is hidden from view within said vehicle at a relatively secure location not visible either from outside the vehicle or from passenger locations within the passenger compartment of said vehicle, and said system further comprises a switch accessible only within said vehicle for selective actuation by the system operator, said control unit being responsive to actuation of said switch for entering the program mode; and further characterized in that said program mode is automatically terminated after a predetermined time delay from receipt of the last transmitted encoded signal.

6. A vehicle security system in which a control unit is responsive to receipt of a proper transmitted encoded radio frequency signal from a transmitter to arm or disarm said system, comprising:

vehicle antitheft means, said means comprising a vehicle ignition disabling means;

a portable hand-held transmitter comprising means for generating and transmitting a predetermined fixed digitally encoded, radio frequency, receiver-responsive signal representative of a predetermined transmitter code; and wherein said predetermined transmitter code comprises a non-user-programmable N-bit digital code word;

a control unit located within said vehicle, comprising:

(i) radio frequency signal receiving means operable during said program mode and during said system operating-receiving mode for receiving said transmitted encoded signal and generating an electrical signal representative of the encoded signal;

(ii) a digital memory for storing signature code signals;

(iii) programming means for recording in said digital memory received signals for arming or disarming said vehicle antitheft means, said means activated only during a system program mode for automatically storing in said memory said electrical signals representative of said radio frequency, receiver-responsive received signals representative of said predetermined transmitter code as a signature code signal for arming or disarming said vehicle antitheft means; and

(iv) operating means activated during an operating-receiving mode for comparing received electrical signals with said signature code signal stored in said memory means to determine if said electrical signals correspond to said recorded signature code signal and for arming or disarming said antitheft means if said electrical signals correspond to said recorded signature code signal, wherein said transmitter and said receiver means cooperate to form a one-way radio frequency signal transmission link for communicating signals only from said transmitter to said receiving means, said transmission link being employed by said system during said programming mode for transmitting said signal representative of said transmitter code to said access control unit to be stored in said memory means as signature code signals, said link further employed during said operating-receiving mode for transmitting said encoded signal from said transmitter to said access control unit.

7. A vehicle security system in which a control unit is responsive to receipt of a proper transmitted encoded radio frequency signal from a transmitter to arm or disarm said system, comprising:

vehicle antitheft means, said means comprising a vehicle ignition disabling means;

a portable hand-held transmitter comprising means for generating and transmitting a predetermined fixed digitally encoded, radio frequency, receiver-responsive signal representative of a predetermined transmitter code;

a control unit located within said vehicle, comprising:

(i) radio frequency signal receiving means operable during said program mode and during said system operating-receiving mode for receiving said transmitted encoded signal and generating an electrical signal representative of the encoded signal;

(ii) a digital memory for storing signature code signals;

(iii) programming means for recording in said digital memory received signals for arming or disarming said vehicle antitheft means, said means activated only during a system program mode for automatically storing in said memory said electrical signals representative of said radio frequency, receiver-responsive received signals representative of said predetermined transmitter code as a signature code signal for arming or disarming said vehicle antitheft means; and

(iv) operating means activated during an operating-receiving mode for comparing received electrical signals with said signature code signal stored in said memory means to determine if said electrical signals correspond to said recorded signature code signal and for arming or disarming said antitheft means if said electrical signals correspond to said recorded signature code signal, wherein said transmitter and said receiver means cooperate to form a one-way radio frequency signal transmission link for communicating signals only from said transmitter to said receiving means, said transmission link being employed by said system during said programming mode for transmitting said signal representative of said transmitter code to said access control unit to be stored in said memory means as signature code signals, said link further employed during said operating-receiving mode for transmitting said encoded signal from said transmitter to said access control unit; further characterized in that said access control unit is operable in the program mode to automatically record a plurality of different transmitter codes from a plurality of different transmitters codes and wherein said control unit is responsive to received signals corresponding to any one of said stored transmitter codes for arming or disarming the vehicle antitheft means; and wherein said transmitter is suitably encoded with said transmitter code by the manufacturer thereof so that the system user is not required to encode said transmitter.

8. A vehicle security system in which a control unit is responsive to receipt of a proper transmitted encoded radio frequency signal from a transmitter to arm or disarm said system, comprising:

vehicle antitheft means, said means comprising a vehicle ignition disabling means;

a portable hand-held transmitter comprising means for generating and transmitting a predetermined fixed digitally encoded, radio frequency, receiver-responsive signal representative of a predetermined transmitter code;

a control unit located within said vehicle, comprising:

(i) radio frequency signal receiving means operable during said program mode and during said system operating-receiving mode for receiving said transmitted encoded signal and generating an electrical signal representative of the encoded signal;

(ii) a digital memory for storing signature code signals;

(iii) programming means for recording in said digital memory received signals for arming or disarming said vehicle antitheft means, said means activated only during a system program mode for automatically storing in said memory said electrical signals representative of said radio frequency, receiver-responsive received signals representative of said predetermined transmitter code as a signature code signal for arming or disarming said vehicle antitheft means; and

(iv) operating means activated during in operating-receiving mode for comparing received electrical signals with said signature code signal stored in said memory means to determine if said electrical signals correspond to said recorded signature code signal and for arming or disarming said antitheft means if said electrical signals correspond to said recorded signature code signal, wherein said transmitter and said receiver means cooperate to form a one-way radio frequency signal transmission link for communicating signals only from said transmitter to said receiving means, said transmission link being employed by said system during said programming mode for transmitting said signal representative of said transmitter code to said access control unit to be stored in said memory means as signature code signals, said link further employed during said operating-receiving mode for transmitting said encoded signal from said transmitter to said access control unit; and wherein said control unit is operable in the program mode to record a plurality of different transmitter encoded signals of different code bit lengths as valid signature code words, and operable in the operating-receive mode to decode and compare said decoded signals of different bit lengths to each of said recorded signature code signals.

9. A vehicle security system in which a control unit is responsive to receipt of a proper transmitted encoded radio frequency signal from a transmitter to arm or disarm said system, comprising:

vehicle antitheft means, said means comprising a vehicle ignition disabling means;

a portable hand-held transmitter comprising means for generating and transmitting a predetermined fixed digitally encoded, radio frequency, receiver-responsive signal representative of a predetermined transmitter code;

a control unit located within said vehicle, comprising:

(i) radio frequency signal receiving means operable during said program mode and during said system operating-receiving mode for receiving said transmitted encoded signal and generating an electrical signal representative of the encoded signal;

(ii) a digital memory for storing signature code signals;

(iii) programming means for recording in said digital memory received signals for arming or disarming said vehicle antitheft means, said means activated only during a system program mode for automatically storing in said memory said electrical signals representative of said radio frequency, receiver-responsive received signals representative of said predetermined transmitter code as a signature code signal for arming or disarming said vehicle antitheft means, and

(iv) operating means activated during an operating-receiving mode for comparing received electrical signals with said signature code signal stored in said memory means to determine if said electrical signals correspond to said recorded signature code signals and for arming or disarming said antitheft means if said electrical signals correspond it said recorded signature code signal, wherein said transmitter and said receiver means cooperate to form a one-way radio frequency signal transmission link for communicating signals only from said transmitter to said receiving means, said transmission link being employed by said system during said programming mode for transmitting said signal representative of said transmitter code to said access control unit to be stored in said memory means as signature code signals, said link further employed during said operating-receiving mode for transmitting said encoded signal from said transmitter to said access control unit; and wherein said transmitter comprises means for selectively generating and transmitting either a first or a second predetermined digitally encoded, radio frequency signal representative of first or second predetermined transmitter codes, said control unit is operable in the program mode to record respective signals representative of said first or second transmitter codes, and wherein said operating means comprises means for arming or disarming said antitheft means in response to receipt of signals corresponding to said first code, and means for performing a second predetermined function in response to signals corresponding to said second transmitter code.

10. An electronically programmable remote control vehicle security system, comprising:

a multi-channel remote control transmitter comprising means for generating a plurality of predetermined digitally encoded, radio frequency, signals representative of a plurality of predetermined transmitter channel signature codes, and user-activated means for selecting and transmitting respective ones of said signals;

vehicle antitheft means;

a system control unit disposed within said vehicle, comprising:

(i) receiving means operable during a system program mode and a system operating-receiving mode for receiving said transmitted encoded signal and generating an electrical signal representative of the encoded signal;

(ii) a digital memory for storing data representative of signature code signals, said memory comprising a plurality of assigned memory locations for storing signature code signals for each of said channels;

(iii) programming means activated only during said system program mode for selecting a particular channel and storing in an assigned memory location in said memory received signals representative of said predetermined transmitter channel code as a signature channel control signal;

(iv) operating means activated during said operating-receiving mode for comparing received electrical signals with said signature control signals stored in said memory means to determine if said electrical signals correspond to said recorded signature code signal, means for determining the channel having a corresponding signature channel control signal stored therein, and responsive action means for the respective identified channel activated upon receipt of a matching channel signature code;

wherein said transmitter and said receiving means cooperate to form a one-way radio frequency signal transmission link for communicating signals only from said transmitter to said receiving means, said transmission link being employed by said system during said programming mode for transmitting said encoded signals from said transmitter to said access control unit to be stored in said memory as said code signals, said link further employed during said operating receiving mode for transmitting said encoded signals from said transmitter to said control unit; and wherein said transmitter is suitably encoded with said predetermined transmitter code by the manufacturer thereof so that the system user is not required to encode said transmitter.

BACKGROUND OF THE INVENTION

This invention relates to certain new and useful improvements in remote control vehicle security systems, and more particularly, to remote control vehicle security systems including a receiver-control unit located in the vehicle, and one or more remote transmitters, and which systems are electronically programmable by the user without knowledge of the specific transmitter code.

In recent years, primarily due to the increase of theft, vandalism and burglaries, many vehicle owners have installed remote control security systems. The vast majority of these security systems, when triggered, will generate an audible or visible alarm signal to alert of an improper entry or intrusion into the vehicle. Many of these commercially available security systems are remotely operable, that is, they include a receiver capable of being operated from a remotely located transmitter for purposes of arming and disarming the security system. Usually, these receiver-transmitter arrangements are radio frequency operated, although they can be operated with other forms of electromagnetic radiation or sound energy.

Automotive vehicle security systems known in the art usually include an alarm section which may either generate an audible alarm, as for example, from a siren, a horn, or the like and may also often activate a visible alarm by operating any of the vehicle lights. Many of these commercially available vehicle security systems may also disable some portion of the vehicle engine system such as the ignition system, starter, fuel pump, or lock the engine compartment. Thus, in the event of an improper intrusion or attempted theft of the vehicle, the security system will cause initiation of an audible alarm or cause the lights to switch on and off and may also interfere with operation of the vehicle engine system. One example of a remote control vehicle security system is disclosed in U.S. pat. No. 4,383,242.

The use of a transmitter and a receiver which have been precoded is generally standard with commercially available remote control vehicle security systems. In these conventional transmitter-receiver combinations, the code, usually referred to as an encoded signal, is permanently encoded into the receiver, and the transmitters is preprogrammed with a code which cannot be altered or changed by the user. Thus, the receiver is operated on the basis of a security code permanently encoded in that receiver and transmitted from a particular transmitter matched and sold with that receiver. Such conventional security systems present a security exposure in case of a lost or stolen transmitter, as well as many constraints on the manufacturers, customers and dealers of these security systems. For instance, if the user of one of these security systems should lose the transmitter, it is necessary to obtain another transmitter which was not previously coded and have that transmitter properly matched and coded for the particular receiver.

The encoding of the transmitter entails obtaining the particular code required to activate the receiver, opening the transmitter housing and mechanically coding the transmitter. Usually, the coding is accomplished by scratching conductive lines on a printed circuit board, closing or opening switches or the like. Some transmitters are provided with control boards having hole areas capable of being punched to provide a particular encoded signal. Thus, some form of mechanical action is usually required for encoding the transmitter.

Most users of remote control vehicle security systems do not have the expertise to encode the transmitter and, therefore, must seek the assistance of the retailer or manufacturer of the system. The mere fact that the code for authorized actuation of the security system must be known by the selling dealer or manufacturer may inevitably lead to a breach of the security system itself, since the code is usually written to maintain a permanent record of the same. More importantly, should the user wish to change the code because of a lost or stolen transmitter, the receiver will have to be sent back to the manufacturer, leaving the user without the security system while this costly task is being performed.

In addition to the foregoing, if a user desires to have several transmitters operate the receivers of several remote control vehicle security systems, each receiver must be properly programmed with the proper code. Thus, if a person desired to operate several vehicles with the same remote control system, it is necessary to have a receiver in each car preprogrammed by a manufacturer. This necessarily requires custom design efforts which is very time consuming as well as costly.

It is, therefore, one of the primary objects of the present invention to provide a radio frequency operated remote control vehicle security system in which the receiver of the system can be electronically programmed by the user of the system without opening the transmitter, and without coding the transmitter or changing or encoding the receiver or acquiring dealer or manufacturer assistance.

It is another object of the present invention to provide a remote control vehicle security system in which neither the manufacturer, dealer or user of the system is required to know the particular code which is transmitted from the transmitter to the receiver.

It is a further object of the present invention to provide a method for a user of a remote control vehicle security system to encode a receiver from a transmitter without any prerequisite skill or the need to even open the case of either the transmitter or the receiver.

It is an additional object of the present invention to provide a remote control vehicle security system where different types of transmitters may be provided and where each transmitter may operate with different numbers of possible code bits.

It is yet another object of the present invention to provide a remote control vehicle security system where several transmitters, each with a different code, may be added to or deleted from the system at will by the user.

It is another salient object of the present invention to provide a remote control vehicle security system which can be activated by one or more of a multi-billion number of possible codes, thereby providing code security of at least two thousand times the code security of prior art systems and yet which can be manufactured at a relatively low cost.

SUMMARY OF THE INVENTION

A remote control vehicle security system which is comprised of at least one receiver connected to electronic or electrical equipment which will enable or perform various functions when activated and one or more transmitters which can actuate the receiver by generation of a code or encoded signal. The receiver is operable with a control unit and this control unit is preferably a microprocessor controlled unit in accordance with the present invention. Moreover, the receiver and microprocessor control unit can perform all of the necessary decoding functions.

In one embodiment of the invention, one or more transmitters forming part of the system may have the provision of an encoder function included therein to generate encoded signals upon actuation of the transmitters. In a preferred form, the transmitter is a microprocessor controlled device for transmitting a plurality of different channel codes, and includes means for selecting a desired channel code and means for transmitting the selected channel code. This embodiment of the invention also comprises a receiver-control unit within the vehicle, and is responsive to the encoded signal to arm or disarm the system.

The control unit performs several primary functions including a decoding function. Thus, when the receiver receives the encoded signal, the microprocessor validates and decodes the transmitted signal. Thus, there is no requirement for the provision of a separate decoder.

The remote control vehicle security system of the present invention is also highly effective in that it is electronically user programmable. Moreover, no tooling or skills are required on the part of the user in order to program the receiver. The user is not even required to open the transmitter case or receiver housing when programming the system. The user of the system may initiate the receiver's program mode so that it will enable recording of subsequent messages or encoded signals received from the transmitter during the program mode. This may be accomplished by activating a program switch either mechanically, electronically or through voice recognition. Thereafter, the user actuates the transmitter, as for example, by pressing a switch on the transmitter. This will cause the encoded signal to be transmitted by the transmitter to the receiver.

The receiver and control unit will operate to decode the transmitted signal, and the decoded signal is then programmed into a memory unit, as hereinafter described, and becomes a "signature code signal" or "signature code word." In this sense, the system of the present invention is user programmable. Moreover, it is not necessary for anyone to know the specific signature code word programmed in the control unit, initially, or at any time thereafter. The control unit will, in effect, have received the signature code of the transmitter and will record that signature code in the control unit memory.

The receiver-control unit may be arranged so as to automatically exit the signature signal program mode after recording thereof. This automatic exit may occur, for example, after a certain time delay in which no further signal has been received. Otherwise, the receiver may be arranged so that it is manually switched by the user out of the program mode.

In a multi-channel form of the invention, the user selects a particular channel in which to record a signature code word, and once the selection is made, a received code word is recorded and assigned by the control unit to that selected channel. A plurality of signature code words may be stored for each channel. During the operating receive mode, received codes are compared to the stored codes for each channel, and when a match is formed, the control unit determines the channe