An Echo Canceller with Controlled Power for Frequency Offset Correction

In an echo canceller (EC) compensating far-end echos affected by frequency offset, the phase loop gain is highly dependent on the echo and signal powers. Adoption of a normalized gain multiplied by the echo power yields an improved robustness. It is shown that the latter gain depends only on the echo-to-signal ratio. Practical implementation of this idea is realized by generating a first unitary echo replica, on which the DPLL will act, and then controlling the output power. The system has the additional advantage of a reduced binary size for the canceller taps.