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Table 6-14. TDRS SSAR IF Service Spacecraft and Ground Segment Channel
Characteristics (cont’d)
Notes:
1. The customer receive center frequency that is scheduled for SN support will be translated to the
center of the IF bandwidth. The signal and carrier frequency will be constrained such that the first
null of the spectrum falls between 2200 and 2300 MHz. The SSAR IF service only supports noncoherent
frequencies. The SSAR IF service supports only one S-band frequency through 1 TDRS
at a time. These frequencies do not include the effects of Doppler shift. The SSAR IF service is not
required to provide a Doppler-corrected IF output signal. The customer provided receiver needs to
handle Doppler.
2. Constraint parameters are contributions from the TDRS spacecraft and the SN ground segment to
the IF interface. Not included in these aggregate distortion amounts are TDRS spacecraft gain
flatness linear and parabolic allowances and phase nonlinearity parabolic and cubic allowances as
described in 405-TDRS-RP-SY-001, WU-02-01, and SY1-89E. Customer and receiver signal
characteristics need to be considered to determine the end-to-end performance. Please contact
GSFC Code 450 for further information.
3. The 3 dB RF bandwidth is larger than the specified 10 MHz bandwidth value specified in Table 6-9.
This value has validated through spacecraft and ground terminal measurements, but may not be
applicable to future TDRS.
6.3.6.2 Potential Signal Parameters and Signal Performance for IF
Service
As discussed earlier, this is not an end-to-end service so a set of well defined customer
signal parameters is not available. This section describes example signal
characteristics and expected performance through the TDRS spacecraft and SN ground
segment. SN IF services are available to customers on a case-by-case basis.
Customers should contact Code 450 if they are interested in this service to determine
expected performance for their specific signal characteristics and receiver.
The performance of the IF link is greatly dependent on the customer provided receiver.
Typically, the SNUG specifies performance at BER of 10 -5 ; BERs better than 10 -5 may
be possible for the automated IF service.
NOTE:
The expected performance is based upon simulation results
only and has not been verified by testing. Data rates and
coding techniques should be carefully considered and
coordinated with GSFC Code 450 to achieve desired BER.
All values in this section assume using a receiver with reasonable implementation loss.
Table 6-15 provides expected required Eb/No values for example data rates and
modulation schemes for a 10 -5 BER. Additionally, Table 6-15 also provides the
theoretical Eb/No and implementation loss values for those modulation and coding
schemes at 10 -5 BER over a simple AWGN channel. Table 6-15 also provides a
potential minimum required P rec (dBW) equation for the example data rates, coding and
modulation schemes through the IF service assuming these expected required Eb/No
values, which were based upon simulation results and have not been verified by testing.
Revision 10 6-49 450-SNUG