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Table 6-12. TDRSS SSA Return Service Customer Platform Signal Constraints
(cont’d)
Notes:
1. The definitions and descriptions of the customer constraints are provided in Appendix E.
2. When a constraint value is listed for a baud rate range and data is transmitted on both channels,
the maximum baud rate of the 2 channels should be used to determine the constraint value
applicable.
3. It is recommended that customers use G2 inversion to increase symbol transition density.
Additionally, biphase symbol formatting increases symbol transition density. CCSDS
randomization is recommended to aid in compliance with the data randomness requirements.
4. The symbol jitter and jitter rate are defined as the customer transmitted signal peak clock
frequency jitter and peak clock jitter rate (sinusoidal or 3 random) as a percent of the symbol
clock rate.
5. The frequency stability requirements are valid at any constant temperature (0.5 C) in the range
expected during the mission. At a minimum, a temperature range of -10 C to +55 C shall be
considered.
6. Noncoherent configurations (DG1 mode 2 and DG2 noncoherent) require a customer transmit
frequency uncertainty of 700 Hz. If a customer cannot accurately define their transmit frequency
to within 700 Hz, a customer can request a reconfiguration which would expand the oscillator
frequency search to 3 kHz for DG1 and SQPSK DG2 configurations and 35 kHz for BPSK and
QPSK DG2 configurations after the start of service.
7. Derivation of the phase noise requirements involved making assumptions about the distribution of
the phase noise power in each frequency region. Since no phase noise PSD will exactly match the
phase noise power distribution assumed for this derivation, phase noise PSDs which are close to
violating the phase noise limits or phase noise PSDs which violate the phase noise limits should be
evaluated on a case-by-case basis to determine their acceptability.
8. For customers receiving Doppler tracking services, more stringent phase noise constraints should
be considered by the customer. It is the responsibility of the customer to ensure customer
transponder / transmitter phase noise performance enables achievement of the desired total
Doppler tracking error performance. Appendix U provides recommended customer phase noise
performance constraints which ensure a total Doppler tracking error (system + customer) ≤ 0.2
rad/sec (1, channel data rate > 1 kbps) or ≤ 0.4 rad/sec (1, channel data rate ≤ 1 kbps)
assuming an averaging time of 1 second.
9. The minimum SHO EIRP should reflect the minimum P rec expected over the service period, where
the P rec can exceed this minimum by no more than 12 dB. An actual customer P rec value that is
12 dB greater than the minimum may cause false PN lock or nonacquisition.
10. Deleted.
11. Deleted.
12. Bandwidth limitation for gain flatness, phase nonlinearity and gain slope while maintaining
consistency with NTIA spectral emission mask (Appendix D):70% of the signal main lobe width or
70 % of the necessary bandwidth whichever is smaller.
13. Coherent return link phase noise user constraint assumes a forward service signal with no phase
noise on it. Phase noise created in the user receiver carrier tracking loop by thermal noise on the
forward link is a component which must be considered as a contributor to the user coherent return
service phase noise.
14. Customers are recommended to provide to the SN a transmitter EVM measurement for each of
their service modes.
6.3.6 Automated IF Service
This section specifies characteristics and recommendations for the SSAR automated IF
service. SN IF services are available to customers on a case-by-case basis. The IF
Revision 10 6-46 450-SNUG