power back-off - technical definition

A feature of asymmetric digital subscriber line (ADSL) modems that dynamically reduces the modem power level at the customer premises in order to eliminate the potential for interference with the analog voice channel resulting from near-end crosstalk (NEXT). Power back-off occurs automatically and reduces the upstream data transmission rate for the duration of the phone call. Fast retrain enables rapid recovery of the upstream transmission rate when the phone call is terminated. See also ADSL, channel, fast retrain, interference, modem, NEXT, and power.