Abstract: A method and system for predistorting a signal before transmission of the signal to compensate for nonlinearities introduced when the signal is transmitted to a receiver. A signal received on a first frequency is evaluated at a receiver to determine whether the received signal includes nonlinearities without comparing the received signal to the original signal or a pilot tone. The nonlinearity data that result from the evaluation are transmitted back to the originator of the signal on a second frequency where the nonlinearity data are used to predistort signals before transmission therefrom. Communication of the nonlinearity data between transmitter and receiver at each site is through a reverse channel which is further controlled by a serial line.