Abstract: A method and apparatus for monitoring and controlling the operating point of a satellite transponder amplifier. In one aspect of the invention, a time domain signal received at a ground station is digitally sampled. Then, a histogram of the received signal is computed. To form the histogram, the digital samples are categorized according to which of a plurality of amplitude ranges each sample falls within. When plotted as a graph, the number of occurrences within each amplitude range forms the histogram. Under low compression levels, the histogram generally appears as an approximately bell-shaped curve. However, under higher compression levels, the bell-shaped curve becomes distorted. By correlating the acquired histogram to a template histogram, an amount of compression can be determined. This amount of compression indicates the operating point of the transponder amplifiers.