Fast scan trainable transmitter

A trainable transceiver for learning the signal characteristics of a received RF signal and for subsequently transmitting a modulated RF signal having the learned characteristics, said trainable transmitter comprising:

• a dynamically tunable antenna having a control input for receiving antenna control signals and having a tunable element for adjusting the resonant frequency of said antenna in response to the antenna control signals applied to said control input, said antenna is adapted to receive an RF signal from a remote control transmitter used to remotely actuate a device, the RF signal having signal characteristics including a data code and an RF carrier frequency that is initially an unknown frequency within a predefined range between a first frequency and a second frequency;
• a tunable RF circuit coupled to said antenna for receiving RF signals received by said antenna, said RF circuit having a data output terminal and a frequency control terminal for receiving frequency control signals, wherein said RF circuit is selectively tuned to a frequency corresponding to a frequency control signal applied to said frequency control terminal, said RF circuit providing any data code present in a received RF signal at said data output terminal whenever the RF carrier frequency of the received RF signal corresponds to the frequency at which said RF circuit is tuned;
• and
• a control circuit coupled to said control input of said antenna, and to said frequency control terminal and said data output terminal of said RF circuit, said control circuit being operative in a training mode and in an operating mode, when in the training mode, said control circuit initiates a training sequence by applying a first frequency control signal to said frequency control terminal and a first antenna control signal to said control input to tune said RF circuit and said antenna to said first frequency and immediately thereafter applying a second frequency control signal to said frequency control terminal and a second antenna control signal to said control input to tune said RF circuit and said antenna to said second frequency and to cause said tunable RF circuit to jump from being tuned to said first frequency to being tuned to said second frequency,
• wherein, during the jump from said first frequency to said second frequency, said RF circuit supplies a detection signal at said data output terminal representing the presence of a received RF signal having an RF carrier frequency within said predefined frequency range, and, in response to said detection signal, said control circuit continues said training sequence by identifying the RF carrier frequency and code of the received RF signal.

A trainable transmitter comprising:

• an antenna for receiving an RF activation signal from a remote control transmitter for a remotely actuated device, the RF activation signal having an RF carrier frequency and code;
• signal generating means having a frequency control terminal, said signal generator generates a reference signal having a reference frequency corresponding to a frequency control signal applied to said frequency control terminal, said signal generating means is coupled to said antenna for transmitting a modulated RF output signal having a carrier frequency related to the frequency control signal supplied to said frequency control terminal;
• a demodulator coupled to said antenna and to an output of said signal generating means for demodulating the received RF activation signal using said reference signal, said demodulator including
• a mixer having a first signal input terminal coupled to an output of said antenna for receiving the RF activation signal and having a second signal input terminal coupled to an output of said signal generating means for receiving said reference signal, said mixer providing a signal having the data code of the activation signal modulated at a modulation frequency representing a difference between the reference frequency and the carrier frequency of the RF activation signal, and
• a filter having an input coupled to an output of said mixer for blocking all signals supplied to the filter input from said mixer except signals having a predetermined modulation frequency, said filter outputting the data code present in the received signal when the reference frequency and the carrier frequency of the activation signal have a predetermined relationship;
• indicating means for providing an indication to a user that an RF activation signal is being received;
• control means coupled to said filter for detecting the presence of a data code at an output of said filter, and coupled to said frequency control terminal of said signal generating means for supplying said frequency control signal, upon entering a training sequence, said control means changes the reference frequency of said reference signal from a lowest frequency to a highest frequency of a frequency range in which a valid carrier frequency of a received RF activation signal may be transmitted without changing the reference frequency to a discrete frequency that is intermediate said lowest and highest frequencies, said control means coupled to said indicating means for activation when a data code is detected at the output of said filter, upon detecting the presence of a data code, said control means changes the reference frequency of said reference signal step by step until a data code is again detected at the output of said filter, said control means identifies an RF carrier frequency of the received activation signal based upon the reference frequency at which a data code was detected, and stores the detected data code and frequency control data representing the RF carrier frequency of the received activation signal;
• and
• an output circuit coupled to said control means, to said antenna, and to said signal generating means for supplying the stored data code to a data input terminal of said signal generating means and supplying a frequency control signal representing the stored frequency control data to the frequency control terminal of said signal generating means such that the carrier frequency of the modulated RF output signal transmitted by said signal generating means is the same as that of the RF activation signal received from the remote transmitter.

A method of training a vehicle transmitter to learn an RF carrier frequency and data code of an RF control signal received from a remote transmitter, for subsequent transmission of an RF signal having the learned RF carrier frequency and data code of the received RF control signal, said vehicle transmitter including an antenna and a receiver, said method comprising the sequentially performed steps of:

• initiating a training sequence in response to an actuation of a switch;
• monitoring an output of the antenna for an RF control signal within a predefined frequency band;
• aborting the training sequence if an RF control signal within the predefined frequency band is not received within a predetermined time period;
• if an RF control signal within the predefined frequency band is detected, discretely tuning the receiver to a series of frequencies within said predefined frequency band until an RF control signal is detected;
• identifying the RF carrier frequency of the received RF control signal;
• storing frequency control data representing the RF carrier frequency of the received RF control signal;
• identifying the data code of the RF control signal;
• and
• storing the identified data code of the received RF control signal.

A method of training a vehicle transmitter to learn an RF carrier frequency and data code of an RF control signal received from a remote transmitter, for subsequent transmission of an RF signal having the learned RF carrier frequency and data code of the received RF control signal, said vehicle transmitter including an antenna and a tunable RF circuit, the method comprising the sequentially performed steps of:

• monitoring an output of the antenna for an RF control signal within a predefined frequency band;
• providing an indication when an RF control signal is being received within the predefined frequency band;
• generating a reference signal having a first predetermined frequency;
• comparing the reference signal to the received RF control signal to determine whether the frequency of the reference signal has a predetermined relationship to the RF carrier frequency of the received RF control signal;
• changing the frequency of the reference signal until the frequency of the reference signal has the predetermined relationship to the RF carrier frequency of the received RF control signal;
• identifying the RF carrier frequency of the received RF control signal based upon the frequency of the reference signal;
• storing frequency control data representing the RF carrier frequency of the received RF control signal;
• demodulating the received RF control signal using the generated reference signal having a frequency with the predetermined relationship to the RF carrier frequency to provide the data code of the RF control signal;
• and
• storing the data code provided by demodulating the received RF control signal.

A circuit for training a vehicle mounted RF transmitter to learn the RF carrier frequency and modulation scheme of an existing transmitter for subsequent transmission, said circuit including an RF circuit and a microprocessor programmed to control said RF circuit to sequentially perform the steps of:

• initiate a rapid frequency scanning sequence of all frequencies lying within a frequency band;
• provide the operator with an indication if an RF signal has been received;
• training to the frequency and modulating scheme of a detected RF signal;
• and
• aborting the training sequence in the event an RF signal is not detected during said rapid frequency scanning sequence.