Methods and circuits using frequency shift keying modulation to transfer data over transmission lines simultaneous with television signals

A method of transferring data over a television signal transmission line comprising the step of transferring the data between a personal computer and a set top box over the television signal transmission line using frequency shift keying modulation in a frequency range that is not within a television signal frequency range to simultaneously conduct the television signal and the data over the television signal transmission line;

• and
• wherein the step of transferring comprises the step of receiving the data from the television signal transmission line which simultaneously conducts a television signal, wherein the step of receiving comprises the step of:
• setting a switch direction that electrically couples the data from the television signal transmission line to provide a buffered modulated data signal;
• receiving the buffered modulated data signal to compensate for a characteristic impedance of the television signal transmission line;
• generating an internal format data signal from the buffered modulated data signal using frequency shift keying demodulation based on a frequency of the buffered modulated data signal;
• and
• converting the internal format data signal to an interface format data signal.

A cable transfer interface circuit that transmits data from a data interface over a television signal transmission line during a transmit operation and that provides data from the television signal transmission line to the data interface during a receive operation, the cable transfer interface circuit comprising:

• a converter that converts a first personal computer voltage level interface format data signal from the data interface to a transmit voltage level format data signal during the transmit operation;
• a transmitter, responsive to the converter, that provides a transmit modulated data signal based on the transmit voltage level format data signal using frequency shift keying during the transmit operation in a frequency range that is not within a television signal frequency range used to conduct the television signal over the television signal transmission line;
• a switch, responsive to the transmitter, that electrically couples the transmit modulated data signal to the television signal transmission line during the transmit operation;
• wherein the switch electrically couples data from the television signal transmission line to provide a receive modulated data signal during the receive operation;
• a receiver, responsive to the switch, that provides a receive voltage level format data signal based on the receive modulated data signal to the converter interface during the receive portion using frequency shift keying demodulation in the frequency range that is not within the television signal frequency range used to conduct the television signal over the television signal transmission line;
• and
• wherein the converter converts the receive voltage level format data signal to a second personal computer voltage level interface format data signal during the receive operation.