A Microprocessor Monitored Feed-Forward Super Trunk CATV Amplifier

This paper describes how a Microprocessor can be used to monitor the performance of an ultra low distortion Feedforward Super Trunk Amplifier System. The method described is capable of detecting changes in the loop cancellation of a Feedforward stage that may be caused by deterioration in the hybrid IC. A reduction in the loop cancellation of a Feed-forward stage results in an increase in the distortion level. Through the use of a Head-End Micro Conputer, a signal is sent to a transponder located in each amplifier station which in turn interrogates each RF hybrid IC in the individual Feedforward Amplifier Stages. The relative degree of loop cancellation is indicated at the end of the cascade by monitoring the amplitude of a tone which is generated by introducing modulation into each RF hybrid IC. This tone is observable on any umodulated carrier used for test purposes.