Narrowband interference identification and rejection applied to baseband radio signals

Describes a system for identifying narrowband interference (e.g. CW and FEK) in a 3 kHz HF radio channel. The system is able to detect and eliminate such interference under severe HF channel conditions of frequency selective fading and noise. This signal processing technique can enhance the performance of broadband (3 kHz) HF radio systems subject to narrowband interference, and an example of this is presented. The performance of the currently implemented algorithm is outlined and the application of the technique to different signal formats is discussed. The system uses a programmable finite impulse response (FIR) filter implemented on a digital signal processor to remove unwanted interference. The signal processor also performs the spectrum analysis of the baseband 3 kHz radio channel and makes the decisions on the structure of the interference to enable rejection to take place