A fast echo canceller initialization method for the CCITT V.32 modem

An investigation is conducted of the use of a fast-converging frequency-domain adjustment method for the echo canceller that conforms to the CCITT V.32 standard. The method requires no additional processor cycles (or cost increase) over that already required during steady-state operation of the V.32 modem, and reduces the training period to a maximum of 7.5 s, and nominally about 2.5 s. The presence of intermediate echoes can be detected naturally with the presented methods. Simple modifications of the new method are also introduced to accommodate special situations where intermediate echoes and/or frequency offset are present