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Tracking performance of unbalanced QPSK demodulators. I - Biphase Costas loop with passive arm filtersUnbalanced quadriphase-shift-keying (QPSK) is an attractive means for transmitting two digital data streams which in general have different average powers, data rates, and data formats. Previous analyses of the tracking performance of Costas loop demodulators of unbalanced QPSK have accounted only for the filtering effect produced by the loop's two arm filters on the equivalent additive noise perturbing the loop. When the bandwidth of these filters is selected on the basis of the order of the data rate, as is typical of optimum Costas loop design, the filtering degradations of the data modulations themselves and the cross-modulation noise produced by their multiplication in the loop often cannot be neglected. The purpose of this paper is to incorporate these additional filtering effects into the analysis. Many of the results obtained herein are in the form of closed-form expressions which can easily be evaluated numerically for design and performance prediction purposes.
Document ID
19780064102
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Simon, M. K.
(California Institute of Technology, Jet Propulsion Laboratory, Pasadena Calif., United States)
Alem, W. K.
(Axiomatix Corp. Marina del Rey, Calif., United States)
Date Acquired
August 9, 2013
Publication Date
August 1, 1978
Publication Information
Publication: IEEE Transactions on Communications
Volume: COM-26
Subject Category
Communications And Radar
Accession Number
78A48011
Funding Number(s)
CONTRACT_GRANT: NAS9-14614
Distribution Limits
Public
Copyright
Other

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