Trainable transceiver capable of learning variable codes

A trainable transceiver for a vehicle for receiving an activation signal that includes a variable code and learning characteristics of the activation signal for subsequently transmitting a signal having the same characteristics for remotely actuating a device, said trainable transceiver comprising:

• an antenna;
• a receiver coupled to said antenna for receiving an activation signal transmitted from a remote control transmitter for actuating a remote device, the activation signal having characteristics including a variable data code;
• a controller coupled to said receiver for identifying one of a plurality of cryptographic algorithms corresponding to the cryptographic algorithm used by the remote control transmitter for generating the variable data code of the received activation signal, storing data identifying the cryptographic algorithm and a serial number for identifying the data code to be transmitted next when in a learning mode, and for generating a data code using the identified cryptographic algorithm and the last stored serial number when in a transmitting mode;
• and
• a transmitter coupled to said controller for receiving the stored data and generating a modulated signal having the same characteristics as the received activation signal and including the data code generated by said controller, and coupled to said antenna for transmitting the modulated signal to the remote device for actuation thereof.

A method of training a vehicle-installed trainable RF transceiver to receive, learn, and subsequently transmit variable code signals having identifiable characteristics received from remote control transmitters used to actuate a device having a receiver, the method comprising the steps of:

• receiving a signal output from the remote control transmitter, the signal having characteristics including a carrier frequency and a variable data code;
• identifying a cryptographic algorithm used to generate the variable code of the received signal from a plurality of prestored cryptographic algorithms;
• deciphering the received data code using the identified cryptographic algorithm to identify a serial number associated with the received data code;
• storing the identified serial number and data representing the identified cryptographic algorithm;
• generating an RF carrier signal having the carrier frequency of the received signal;
• generating a data code for transmission using the identified cryptographic algorithm and the stored serial number;
• modulating the carrier signal with the generated data code to produce an output signal related to the received signal;
• and
• transmitting said output signal to the receiver of the device in order to remotely actuate the device.

An RF transmitter for use in controlling at least one garage door opening mechanism, said transmitter trainable to the frequency and code of at least one existing garage door opening transmitter, said RF transmitter comprising:

• means for receiving an encoded RF signal from an existing RF remote control transmitter;
• an RF frequency output circuit;
• a microprocessor programmed to operate in a training mode and an operating mode, said microprocessor coupled to said receiving means and to said RF frequency output circuit and when in a training mode operable to identify a code as a variable code, identify one of a plurality of cryptographic algorithms used to generate the variable code, and to store signals identifying the RF frequency of the received encoded RF signals and the identified cryptographic algorithm;
• and
• an operator actuated switch coupled to said microprocessor for controlling the operational state of said microprocessor between said training and operating modes, said microprocessor coupled to said RF frequency output circuit and responsive to the actuation of said switch and said stored signals to generate a variable code and to transmit signals having an RF frequency corresponding to the received encoded RF frequency signals and including a variable code generated by said microprocessor using the identified cryptographic algorithm when in said operating mode when said switch is actuated by an operator.