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6.1 General
Section 6. SSA Telecommunications Services
6.1.1 Available Services
TDRSS SSA services include forward and return telecommunications services, and
tracking services. SSA return service includes service through the SN receive
equipment and an automated IF service, where SN IF services are available to
customers on a case-by-case basis, IF service requires the customer to provide the
receiver equipment and the SN only provides the signal at the IF. Tracking services are
discussed in Section 9. This section focuses on the RF interface between the TDRS
and the customer platform. This interface is characterized by the technical
requirements imposed and the operational capabilities provided by the TDRSS. The
operational interfaces are described in further detail in Section 10. Data interfaces
between the customer MOC and the SN are described in Section 3, paragraph 3.6.
NOTE:
The NCCDS issues NAMs to provide up-to-date information
on network conditions and constraints. These messages are
accessible via the NCCDS active NAM web site at
https://cds.gsfc.nasa.gov/. The GSFC Code 450 uses the
NAMs as a means of letting customers know of any
performance constraints associated with the TDRS
spacecraft. Additionally, TDRS constellation information can
be found in the TDRS Constellation Management Plan, 452-
PLAN-0002.
6.1.2 Interface Definition
The RF interface between the TDRS and a customer platform is defined in terms of
signal parameters, RF characteristics, and field of view.
a. The RF interface for forward service represents the transmission by a TDRS of
an appropriately modulated signal at or greater than a minimum signal EIRP in
the direction of the desired customer platform. SSA forward (SSAF) service is
discussed in paragraph 6.2.
b. The RF interface for return service defines a minimum received power (Prec) at
the TDRS antenna input for a specified data quality at the SN ground terminal
receiver output. SSAR service is discussed in paragraph 6.3.
NOTE:
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.
Revision 10 6-1 450-SNUG