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Performance of the Dsa's Subcarrier Demodulation Digital LoopThe subcarrier demodulation digital loop is part of the baseband assembly. The subcarrier demodulator is a fourth-order Costas-type loop corresponding to a type 2 analog loop in terms of steady state response. The expected value and the variance of the error signal are determined as functions of the input SNR. A Nyquist sampling rate of the input signal is assumed. From the integro-difference equations a mixed s/z domain block diagram is obtained. From the loop's transfer function a set of gains for the loop filter is obtained. Also, a set of state equations is presented for future reference. Finally, the noise-equivalent bandwidths are calculated for normalized computation times of 0, 0.25 and 0.5. The subcarrier demodulator analyzed tracks a parabolic phase input with finite steady state error. Since at each update instant the loop gains are adjusted to compensate for the variations in SNR of the input signal, the noise-equivalent bandwidth is maintained constant.
Document ID
19850010932
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Simon, M. K.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Mileant, A.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
August 12, 2013
Publication Date
February 15, 1985
Publication Information
Publication: The Telecommun. and Data Acquisition Rept.
Subject Category
Communications And Radar
Accession Number
85N19242
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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