Making nonlinear interference rejection work in QPSK-SS receivers

Author

Abrams, Burton S.

Author_Institution

Zeger-Abrams Inc., Glenside, PA, USA

Volume

2

fYear

1995

fDate

35010

Firstpage

774

Abstract

A strong memoryless nonlinearity excited by a strong interference and a weak QPSK spread spectrum (SS) signal produces the weak signal and an intermodulation product (IMP) with equal amplitudes. With QPSK modulation used for both the data and the SS code, it is shown that the conventional QPSK-SS demodulator´s SS processing cannot discriminate between the signal and the IMP even though it can discriminate the weak signal from the strong interference. An alternative QPSK-SS configuration is presented which overcomes this IMP interference vulnerability while still suppressing the strong interference

Keywords

demodulation; demodulators; filtering theory; interference suppression; intermodulation; matched filters; quadrature phase shift keying; radio receivers; radiofrequency interference; spread spectrum communication; QPSK modulation; QPSK spread spectrum signal; QPSK-SS demodulator; QPSK-SS receivers; data; intermodulation product; matched filter demodulation; memoryless nonlinearity; nonlinear interference rejection; spread spectrum code; spread spectrum processing; strong interference suppression; weak signal; Additives; Demodulation; Interference suppression; Matched filters; Modulation coding; Phase modulation; Quadrature phase shift keying; Repeaters; Signal processing; Spread spectrum communication;

fLanguage

English

Publisher

ieee

Conference_Titel

Military Communications Conference, 1995. MILCOM '95, Conference Record, IEEE

Conference_Location

San Diego, CA

Print_ISBN

0-7803-2489-7

Type

conf

DOI

10.1109/MILCOM.1995.483632

Filename

483632