Title :
An HF modem with increased immunity against multipath
Author :
Loubser, J. ; Pauw, C.K.
Author_Institution :
Dept. of Electron. & Comput. Eng., Pretoria Univ., South Africa
Abstract :
A direct-sequence spread-spectrum technique with low spreading factor is investigated for a 1200-baud modem with increased immunity against multipath propagation. Spread-spectrum techniques are used in conjunction with two DQPSK (differential quadrature phase shift keying) systems overlapping almost totally in the frequency domain. They system has increased immunity against multipath and reduced receiver complexity with not much more bandwidth than a system using a single PSK channel. The price being paid for this advantage is the loss of a few dBs on the noise performance of the system
Keywords :
fading; modems; phase shift keying; radiowave propagation; spread spectrum communication; DQPSK systems; HF modem; differential quadrature phase shift keying; direct-sequence spread-spectrum technique; fading; frequency domain; increased immunity; low spreading factor; multipath propagation; Band pass filters; Bandwidth; Computational modeling; Finite impulse response filter; Frequency domain analysis; Hafnium; Matched filters; Modems; Spread spectrum communication; Transmitters;
Conference_Titel :
Communications and Signal Processing, 1989. COMSIG 1989. Proceedings., Southern African Conference on
Conference_Location :
Stellenbosch
Print_ISBN :
0-87942-713-2
DOI :
10.1109/COMSIG.1989.129011
