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Table 6-7. TDRSS SSA Return Service Signal Parameters (cont’d)
DG2 (note 1) (cont’d)
Parameter (Note 6) Description (Note 6)
Periodic convolutional interleaving (note 4) Recommended for baud rates > 300 kbps
Symbol format NRZ, Bi0/-L
Data format NRZ-L, NRZ-M, NRZ-S
Data rate restrictions
DG2
Total (note 1) I (max) + Q (max)
I channel 1 kbps - 3 Mbps
Q channel 1 kbps - 3 Mbps
I channel power
Q channel power
restrictions
Single data source-alternate I/Q bits 1:1
Single data source-alternate I/Q encoded
symbols
Revision 10 6-21 450-SNUG
1:1
Single data source-single data channel NA
Dual data sources 1:1 or 4:1
Notes:
1. Customer platform data configurations, including specific data rate restrictions for coding and
formatting, are defined in Table 6-8 for TDRSS SSA return service (refer also to Appendix B).
Unless otherwise stated, the data rate restrictions given in this table assume rate 1/2
convolutional encoding and NRZ formatting.
2. For DG1, the Q/I power parameter range can vary from 1:1 to 4:1 continuously during
specification of applicable parameter values in the NCCDS scheduling database and during realtime
service reconfiguration. However if this parameter is re-specified in schedule requests to the
NCCDS (refer to Section 10, paragraph 10.2.2), it is expressed as the ratio of two single-digit
integers.
3. The Q channel PN code sequence must be identical to the I channel PN code sequence, but
offset by x + 1/2 PN code chips, where x 20,000. The value of x is defined by the PN code
assignment for a particular customer platform (refer to 451-PN CODE-SNIP).
4. Periodic convolutional interleaving (PCI) recommended on S-band return services for channel
baud rates > 300 kbps. Biphase symbol formats are not allowed with PCI. When interleaving is
not employed for channel baud rates > 300 kbps, S-band return performance may not be
guaranteed.
5. The center frequency, fo , of the customer platform transmitter must be defined by the customer
MOC in its service specification code to an integral multiple of 10 Hz.
6. Unless otherwise noted, all data rate values are to be interpreted as data bit rates, and not as
data symbol rates. Data rates and modulation schemes are based upon support through the
SSAR SN ground terminal receivers. Other data rates and modulation schemes are possible
through the SSA return automated IF service, which is available on a case-by-case basis. Please
refer to paragraph 6.3.6 and contact GSFC Code 450 for further information.