A method and apparatus for rapid initialization of the transversal filter efficients in an echo canceler or echo measurement device is described. During initialization, a first data sequence is applied to a transmission channel, and an error signal representing the difference between the resulting echo and a replica thereof generated by the transversal filter is formed. The coefficients used to form the replica (in the case of an echo canceler) or to model the transmission channel (in the case of an echo measurement device) are then updated as a function of the error and a second data sequence which is orthogonal to the first sequence.