SN User's Guide - ESC Home - NASA

NOTE:
Customers who operate in a SS-BPSK mode for one service
cannot reconfigure any of their Forward Services (i.e., MAF,
SMAF, SSAF, KuSAF, or KaSAF) to an SS-UQPSK mode.
Contact Code 450 if additional flexibility is required.
b. Asynchronous Data Modulation. The forward service data will be asynchronous
with the carrier.
c. Functional Configurations. A further description of the functional configurations
and data polarity ambiguity is found in Appendix B, paragraph B.2.2.
d. Doppler Compensation. The TDRSS MA forward service carrier frequency (F)
transmitted by a TDRS can optionally be compensated by the SN ground
terminal for Doppler. When compensated, the carrier, FR, arrives at the
customer platform receiving system within a predictable tolerance (E) of fo as
defined in Table 5-1. This feature minimizes the Doppler resolution
requirements of the customer platform receiver and is available continuously to
facilitate reacquisition by the customer platform in the event of loss of lock of
the TDRSS MA forward service signal. Customers are encouraged to utilize GT
Doppler compensation unless the customer is relying on measuring the Doppler
onboard for tracking data. Doppler compensation may be inhibited and the
TDRSS will transmit a fixed frequency MA forward service carrier.
5.2.3 Communications Services
The TDRSS MA forward services available are listed in Table 5-2. Table 5-3 lists their
salient characteristics. The definitions for the parameters listed in Table 5-3 are
contained in Appendix E.
5.2.4 Real-Time Configuration Changes
Changes to the operating conditions or configuration of a TDRS MA forward service
during a scheduled service support period are usually initiated by a Ground Control
Message Request (GCMR) from the customer MOC. The requested changes will be
implemented within 35 seconds of receipt of the GCMR at the SN ground terminal. The
MOC will be notified upon initiation of the requested changes via GCM. Additional
information concerning SN ground terminal response times for the GCMRs is provided
in Section 10. Table 5-4 lists the MA forward service real-time configuration changes
and their effects on the forward service signal.
Revision 10 5-7 450-SNUG