Improved instantaneous frequency-based interference excision in DS/SS communications
R.S. Ramineni, Moeness G. Amin, Stephen R. Lach · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1998
In this paper, the well known notch filtering technique for interference excision in direct sequence spread spectrum communications is expanded, so as to remove the constraint that the instantaneous frequency (IF) of the jammer must be constant over the filter duration. The time-varying difference equation representation of a polynomial phase signal is used to define a new filter impulse response that can effectively remove a y polynomial phase interfering signal. It is shown that thus approach, when applied to jammers with constant modulus property, is more efficient than the existing excision methods implementing notch excision filtering. This paper focuses specifically on chirp signals, and provides both the receiver SNR and bit error rate curves, thus showing the improved performance over similar approaches based on instantaneous frequency information.