Communication system having transmitter frequency control

An RF transceiver for receiving a transceiver input RF signal and for transmitting a transceiver output RF signal in response to the input RF signal, the input RF signal being modulated with data characterized by a data clock frequency, comprising:

• a) a receiver section including
• i) an input stage, connected to receive the transceiver input RF signal, for demodulating the input RF signal to produce a receiver clock signal having a frequency the same as the data clock frequency of the input RF signal, and
• ii) a tracking oscillator, connected to receive the receiver clock signal, for producing a reference signal having a frequency which is locked to the frequency of the receiver clock signal;
• and
• b) a transmitter section having a frequency multiplier circuit, connected to receive the reference signal, for producing a transceiver output RF signal having a frequency which is the product of the frequency of the reference signal and a predetermined multiplying factor, wherein the frequency of said output RF signal is not based on any frequency reference which is independent of said reference signal;
• c) whereby the frequency Of the transceiver output RF signal is controlled by the data clock frequency of the transceiver input RF signal.

An RF transceiver for receiving a transceiver input RF signal and for transmitting a transceiver output RF signal in response to the input RF signal, the input RF signal being modulated with data characterized by a data clock frequency, comprising:

• a) a receiver section including
• i) an input stage, connected to receive the transceiver input RF signal, for demodulating the input RF signal to produce a receiver clock signal having a frequency the same as the data clock frequency of the input RF signal,
• ii) a phase comparator, connected to receive the receiver clock signal and a reference signal, for producing a comparator output signal having a value selected from a first value, a second value, and a third value according to whether the reference signal has a phase angle which is respectively lagging, leading, or close to the phase angle of the receiver clock signal,
• iii) a digital counter for producing a digital count which increments in response to the comparator output signal having the first value and which decrements in response to the comparator output signal having the second value,
• iv) a digital-to-analog converter for producing an analog control signal whose value is proportional to the digital count, and
• v) a controlled oscillator for producing said reference signal having a frequency established in response to the analog control signal;
• and
• b) a transmitter section, connected to receive the digital count, for producing a transceiver output RF signal having a frequency controlled by the digital count;
• c) whereby the frequency of the transceiver output RF signal is controlled by the data clock frequency of the transceiver input RF signal.

An RF transceiver for receiving a transceiver input RF signal conveying a message and for transmitting a transceiver output RF signal in response to the input RF signal, the input RF signal being characterized by one or more characteristic frequencies, comprising:

• a) a receiver section including
• i) an input stage, connected to receive the transceiver input RF signal, for producing a receiver clock signal having a frequency the same as one of the characteristic frequencies of the input RF signal,
• ii) a tracking oscillator, connected to receive the receiver clock signal, for producing a reference signal having a frequency which is locked to the frequency of the receiver clock signal, wherein the tracking oscillator includes a controlled oscillator, having an input connected to receive a control signal, for producing said reference signal and for establishing the frequency of the reference signal in response to the control signal,
• iii) a communication processor for detecting whether the transceiver input RF signal includes an error-free message and, if so, for producing a hold signal, and
• iv) a latch circuit for storing the value of the control signal when the communication processor produces the hold signal and for providing the stored control signal value to the input of the controlled oscillator when a transceiver input RF signal is absent;
• and
• b) a transmitter section, connected to receive the reference signal, for producing a transceiver output RF signal having a frequency derived from the frequency of the reference signal;
• c) whereby the frequency of the transceiver output RF signal is controlled by said one characteristic frequency of the transceiver input RF signal, and whereby the frequency of the transceiver output RF signal remains controlled even when a transceiver input RF signal is absent.