Suppression of Pulsed CW Interference in QPSK Systems Using Decision-Feedback Filters

Iwao SASASE  Shinsaku MORI  

IEICE TRANSACTIONS (1976-1990)   Vol.E73   No.7   pp.1187-1197
Publication Date: 1990/07/25
Online ISSN: 
Print ISSN: 0000-0000
Type of Manuscript: PAPER
Category: Radio Communication

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The performance of QPSK systems using decision-feedback (DF) filters in the presence of the pulsed continuous wave (CW) interference is analyzed. We derive the general analytic expressions for the optimum tap weights and the improvement factor of the signal-to-noise ratio (SNR) for both one-sided and two-sided transversal filters with and without DF taps. We find that in the presence of the pulsed CW interference, the leading taps of the two-sided filter plays an important role to suppress the pulsed CW interference, and therefore, the output SNR of the two-sided filter with DF is most improved. The transient behavior of the DF filters are also considered and it is found that the settling time of the two-sided filter with DF is almost the same as that one-sided filter with DF.