SN User's Guide - ESC Home - NASA

4. To avoid interference with MA return customers, the SN may restrict
support to SSA only customers that operate LHC polarization at
frequencies above 2280 MHz.
5. The SSA forward and return polarization must be the same in order to
obtain simultaneous forward and return services through the same TDRS
SA antenna.
c. Mutual Interference. It is possible for the mutual interference between SSA
customer platforms operating on the same polarization to become significant.
The SN can provide tools to assist customers in interference prediction and
interference mitigation.
NOTE:
Frequency assignment and polarization selection for TDRSS
SSA return service customers is performed during the
mission planning phase.
6.3.4 Real-Time Configuration Changes
Changes to the operating conditions or configuration of a TDRSS SSA return service
during a scheduled service support period are initiated by a 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 GCMRs is provided in Section 10. Table 6-11 lists the SSA return
service real-time configuration changes and their effects on the return service.
6.3.5 Acquisition Scenarios
The following acquisition scenarios identify only the technical aspects of TDRSS SSA
return service signal acquisition by the SN ground terminal and do not include
operational procedures related to acquisition. Acquisition is dependent upon the
customer providing an ephemeris with a maximum uncertainty as defined in Table 6-9:
a. Coherent Modes (DG1 Modes 1 or 3 and DG2 Coherent)
1. For optimal TDRSS performance, all coherent services should have the
TDRSS forward and return services starting at the same time. If
operational considerations require starting the TDRSS forward service
before the return service, no reconfigurations of the forward service can
be sent within 30 seconds of the start of the return service. A forward link
sweep request OPM cannot be sent within 150 seconds of the start of the
return service.
Revision 10 6-36 450-SNUG