SIGNAL PRESENCE DETECTOR

摘要

A signal presence detection device (500) has a first reference voltage generation device in the form of a first voltage divider, a second referenc voltage generation device in the form of a second voltage divider and a third reference voltage generation deivce in the form of a third voltage divider. The detection device also has a signal conditioning device (508) such as a hysteretic amplifier with an output that is coupled to the first and second voltage dividers. A comparison device is coupled to all three voltage dividers to compare a voltage of the first voltage divider to a voltage of the third voltage divider and to compare a voltage of the second voltage divider to the voltage of the third voltage divider. The comparison device is coupled at two outputs thereof to two respective inputs of an XOR device (514). The XOR device receives respective signals from the first and second outputs of the comparison device and produces a signal presence output that serves to indicate whether an incoming signal is present or absent.