Miniaturized reverse modulation loop of a CQPSK 120 Mbit/s modem for spacecraft applications

Author

Kirmse, Karen H.R. ; Gupta, Ramesh K. ; Assal, François T. ; Kroll, Robert T.

Author_Institution

Dept. of Electr. & Comput. Eng., Wisconsin Univ., Madison, WI, USA

Volume

40

Issue

6

fYear

1992

fDate

6/1/1992 12:00:00 AM

Firstpage

1165

Lastpage

1170

Abstract

The design and performance of a miniaturized reverse modulation loop (RML) for a 120 Mbit/s coherent quadrature phase shift keying (CQPSK) modem for onboard satellite applications are presented. Analysis of time delays within the RML circuit indicates that any differential time-delay errors can adversely affect the associated BER and should be minimized. The RML circuit, consisting of a modulator, demodulator, and comparator circuit, has been fabricated using quasi-monolithic techniques with dimensions of 1.65×4 cm. The relative phase for all four states of the modulator is in close agreement with design values of 90°±1° over a 200 MHz bandwidth at 3.95 GHz. The demodulator and comparator circuits of the RML have successfully recovered a 120 Mbit/s bit stream. The RML circuit is capable of recovering higher bit rates because of relatively uniform amplitude and phase performance over the 3.7- to 4.2 GHz communications satellite band

Keywords

demodulation; modems; phase shift keying; satellite relay systems; 120 Mbit/s; 200 MHz; 3.95 GHz; BER; CQPSK; RML; bandwidth; bit stream recovery; coherent QPSK; coherent quadrature phase shift keying; communications satellite band; comparator circuit; demodulator; differential time-delay errors; miniaturized reverse modulation loop; modem; modulator; onboard satellite applications; quasi-monolithic techniques; spacecraft applications; time delays; Bandwidth; Bit error rate; Bit rate; Circuits; Delay effects; Demodulation; Modems; Phase modulation; Quadrature phase shift keying; Satellites;

fLanguage

English

Journal_Title

Microwave Theory and Techniques, IEEE Transactions on

Publisher

ieee

ISSN

0018-9480

Type

jour

DOI

10.1109/22.141348

Filename

141348