Method and apparatus for energy detection in a modem

A method of energy detection for detecting a valid incoming signal in a modern, comprising the steps of:

• (a) processing a prescribed number of signal samples of a signal from which most out-of-band interference and noise has been rejected;
• (b) determining an average energy level for the prescribed number of signal samples;
• (c) determining a gain of an amplifier based on the incoming signal;
• and
• (d) declaring the valid signal when the average energy level is greater than a prescribed energy level threshold and when the gain of the amplifier is less than a prescribed amplifier gain threshold.

A method of energy detection for detecting a valid incoming signal in a receiver of a modem, comprising steps of:

• (a) processing 2k×N signal samples, where N represents a time constant and k represents a detection accuracy parameter;
• (b) determining an average energy level for the signal samples:
• (c) determining a gain of an amplifier based on the incoming signal;
• (d) coming the average energy level with a prescribed energy level threshold;
• and
• (e) comparing the gain of the amplifier with a prescribed amplifier gain threshold, wherein if the average energy level is greater than the prescribed energy level threshold and if the gain of the amplifier is less than the prescribed amplifier gain threshold, detection of the valid signal is declared.