A method of estimating an echo return loss of a communication link measures the
peak power value of a signal received from a far end of a communication link and
the corresponding peak power value of a signal received from the near end of the
communication link. When the near end signal is free from near end voice and excessive
noise, the near end corresponding peak will be the echo of the far end power. The
far end power is monitored and when a peak is detected, a period, which can be
equal to a filter length period, is initiated. When the period has run, the delay
line attached to the near end is polled to determine the peak power in the delay
line. This peak power will correspond to the far end peak. If a peak, exceeding
the first peak is detected before the period has run, the period is reinitiated.
The echo return loss estimate is calculated as a ratio of the far-end peak power
value to the near-end peak power value. The measured far-end signal is the payload
information that the communication link was established to convey and the measured
near-end signal is the echo of the payload.