Conference Paper

On the power spectral density of SGLS and USB waveforms

Aerosp. Corp., Los Angeles, CA
DOI: 10.1109/AERO.1999.793154 Conference: Aerospace Conference, 1999. Proceedings. 1999 IEEE, Volume: 2
Source: IEEE Xplore

ABSTRACT Most of the DoD satellites utilize the Space-to-Ground Link
Subsystem (SGLS) for tracking, telemetry, and command (TT and C)
controls. The standard SGLS waveform uses a phase modulation (PM) scheme
on the combined PCM/FSK/AM signal and pseudo-random noise (PRN) square
wave signal for command and ranging, respectively. The SGLS uplink
operates in the 1755-1850 MHz (L-band), while the downlink operates in
the 2200-2290 MHz (S-band). On the other hand, the non-DoD satellites
for other various governmental agencies primarily use Unified S-Band
(USB) for their TT and C links. Two waveforms, PCM/PSK/PM and
PCM/PM/Bi-Phase, are mainly used in the USE for command along with
either PRN squarewave or sinusoidal tone for ranging. Due to a high
demand of utilizing the L-band for the mobile satellite services, the
government has been thinking of migrating its SGLS uplink from L-band to
USB to avoid the increasing radio frequency interference (RFI) from/to
other mobile satellite systems. Such a migration raises a concern with
respect to interference between the immigrated and existing links. To
study the RFI impact, the power spectrum density (PSD) of both SGLS and
USE waveforms and their respective bandwidth efficiency need to be
studied. This paper derives the PSD for the SGLS and USB waveforms and
compares their respective occupied bandwidths

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    ABSTRACT: The performance of deep-space telemetry signals that employ a residual carrier modulation technique is compared in the presence and absence of a subcarrier. When the subcarrier is present, the performance for the resulting pulse-coded modulation/phase-shift keyed/phase-modulated (PCM/PSK/PM) scheme is evaluated for both sine-wave and square-wave subcarriers and non-return-to zero (NRZ) data. When the subcarrier is absent, the performance for the resulting PCM/PM technique is evaluated for both the NRZ and the bi-phase data format. The comparison is based on telemetry performance as well as bandwidth efficiency. The first criterion is characterized in terms of the symbol error rate (SER) as a function of symbol SNR, loop bandwidth-to-data rate ratio, and modulation index. The bandwidth efficiency is characterized by the occupancy factor. The results of both the analysis and measurements show that when the interference-to-carrier ratio (ICR) is less than -20 dB, the performance degradation in the absence of a subcarrier is negligible. Various combinations of loop bandwidth-to-data rate ratios and modulation indices that achieve this performance are derived and listed. Bandwidth occupancy comparison indicates that PCM/PM/NRZ is the most efficient in this regard. Therefore, by eliminating the subcarrier and using the PCM/PM/NRZ scheme, many advantages can be realized without any sacrifice in performance
    IEEE Transactions on Electromagnetic Compatibility 03/1994; · 1.33 Impact Factor