copending u s patent application entitled 34 modem circuitry 34 filed by shahid qureshi on the same day as this application and hereby incorporated by reference in general the modem while on line monitors the average strength of the signal samples produced by a d converter 64 at a rate of 7 200 times per second when a preselected threshold strength is exceeded mpu 30 raises a carrier detect condition and sets an initial gain factor g for agc 62 with carrier detected and gain initialized the receiver enters a timing jam mode in which one out of six consecutive samples produced by a d converter 64 is selected by mpu 30 for equalization and demodulation thereafter the tap coefficients of the equalizer are set to initial values the above steps completed the receiver enters a data mode wherein the agc timing rate carrier phase and equalizer tap coefficients are continually updated the average signal strength is also continually computed when it falls below a preselected carrier off threshold a carrier loss signal is raised taking the modem out of data mode further details of overall operation appear in the above identified copending application aspects of the operation relating to the invention claimed herein are as follows we turn to a description of the receiver 39 s operation in the data mode assuming that the carrier detect gain initialization timing jam and equalizer initialization functions have.