Single voltage controlled oscillator modem

DETAILED DESCRIPTION A modem is provided for transmitting data at a transmitting frequency and receiving data at a receiving frequency, where the transmitting frequency and the receiving frequency are different, the modem having an oscillator for generating a first signal, a voltage controlled oscillator for generating a second signal, mixer for mixing the first and second signals to provide a mixer output signal having the transmitting frequency, an input data switch for modulating the mixer output signal in accordance with input data, a second mixer connected to the voltage controlled oscillator and to the received incoming signal and a receiver for demodulating the received signal data.
A further feature of the invention is the provision of a channel selector connected to the voltage controlled oscillator for selecting the channel over which data is transmitted and received.
A still further feature is the provision of a modem over which both digital data and audio signals may be transmitted.