Performance of Alternative Adaptive Interference Canceller Configurations in a Shipboard Environment

The effectiveness of U. S. Navy HF communications in a shipboard environment can be limited by the ability of the receiving subsystem to cope with self-interference caused by simultaneously operating, collocated high power transmitters. In existing shipboard RF architectures, the limited dynamic range of the receiver is accommodated by frequency management and the use of tuned multicoupler or preselector equipment that provides isolation from high level fundamental signals. Although these methods are effective, they constrain spectrum access, frequency agility and instantaneous bandwidth characteristics essential to the introduction of jam and intercept resistant waveforms. A new wideband RF architecture using adaptive interference cancellation is being investigated to overcome these constraints. The adaptive interference canceller (AIC) processes samples of each transmitted signal in a manner such that when delivered to the receiving subsystem, the processed sample cancels the signal that propagates from the transmitting antenna to the receiving antenna. This paper addresses testing of an experimental AIC referred to as the Ship Test Set (STS), that is capable of cancelling a single fundamental signal. The paper discusses testing conducted aboard the USS AINSWORTH and at NRL's Pomonkey Test Range. The report shows that for fundamental signal bandwidths of 80-kHz, 30-dB cancellation or better is achieved during testing for 90% of the 2-30 MHz band.