Abstract: The operating point of a nonlinear amplifier is determined by injecting a known test signal into the communication channel and measuring the gain of the amplified test signal. Each amplifier is characterized by a small signal gain curve that relates the gain of the test signal to the input power of the amplifier. In the amplifier's nonlinear range, the gain uniquely determines the input power level of the amplifier, which in turn uniquely determines the operating point of the amplifier. The invention is particularly applicable to satellite transponder architectures that employ "burst" transmission schemes and phased array antennas.