Double quadriphase modulation/demodulation technique for three-channel communication linkA modulation technique for a three-channel communication link is introduced. The structure of the modulator is such as to form an unbalanced quadriphase signal wherein the high rate data stream is bi-phase modulated on the in-phase carrier component, while the sum of the two lower rate signals is bi-phase modulated on the quadrature component of the same carrier. The sum of the two lower signals is, in turn, formed by modulating with the respective data streams the in-phase and the quadrature components of a square wave subcarrier. At the demodulator, the tracking of the carrier and the subcarrier is performed by two independent Costas loops. The demodulation of the high data rate signal is carried out after establishing the carrier reference signal, while the lower rate signals are demodulated after the subcarrier loop recovers the subcarrier. In this paper, the performance of the two loops is analyzed and the expressions for the tracking errors are derived. Finally, a numerical example pertaining to the Space Shuttle-to-TDRS Ku-band link is presented for illustration.
Document ID
19790030246
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Alem, W. K. (Axiomatix Marina del Rey, Calif., United States)
Date Acquired
August 9, 2013
Publication Date
January 1, 1977
Subject Category
Space Communications, Spacecraft Communications, Command And Tracking
Meeting Information
Meeting: In: International Telemetering Conference