An FM Detector for Low S/N

Author

Park, John H., Jr.

Author_Institution

Univ. of Minnesota, Minneapolis, Minn.

Volume

18

Issue

2

fYear

1970

fDate

4/1/1970 12:00:00 AM

Firstpage

110

Lastpage

118

Abstract

Conventional frequency-modulation (FM) detectors show a marked decrease in output $S/N$ below an input $S/N$ of 5 to 10 dB. This threshold effect is caused by "clicks" or phase slips of multiples of π. This effect is related to a normalization (clipping) which is very beneficial at high $S/N$ . A detector is described which has no normalization and is superior to the ideal detector below zero to 10 dB input $S/N$ . The noise at the output of the detector is additive for all input $S/N$ ratios and in this sense is comparable to synchronous detection of AM. Plots of output noise spectrum and output $S/N$ with and without sine-wave modulation are given. Another detector is also proposed that is asymptotic to the ideal detector at high $S/N$ and the aforementioned detector at low $S/N$ . Comparison is made with conventional detectors. The results indicate that this detector may be especially useful in the detection of frequency-shift keying and phase-shift keying in telemetry systems.

Keywords

Additive noise; Communications technology; Filters; Frequency modulation; Performance analysis; Phase detection; Phase frequency detector; Phase shift keying; Signal to noise ratio; Silicon compounds;

fLanguage

English

Journal_Title

Communication Technology, IEEE Transactions on

Publisher

ieee

ISSN

0018-9332

Type

jour

DOI

10.1109/TCOM.1970.1090343

Filename

1090343