Patent ID: 7123651

Claim:
A method of operating a modem, comprising the steps of: (A) transmitting an invalid signal from said modem a plurality of times, a respective one of said transmissions at each of a plurality of settings for an echo cancelling hybrid of said modem, wherein (i) said invalid signal is at a power level below that of a valid signal, (ii) said invalid signal comprises a plurality of test signals at discrete frequencies and (iii) each of said test signals is at a respective power level below a spectral mask defining said valid signal; (B) calculating a plurality of merit values, a respective one of said merit values for each echo signal received by said modem at a respective one of said settings, by integrating said echo signal at each of said respective settings over a predetermined frequency range; (C) determining an approximate distance to a remote transmitter; and (D) adjusting said echo cancelling hybrid to a particular setting of said settings as determined from both (i) said merit values and (ii) said approximate distance.