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