SN User's Guide - ESC Home - NASA

Table 7-5. TDRSS KuSA Return Service Signal Parameters (cont’d)
DG2 (Notes 1, 6)
Parameter (Note 5) Description (Note 5)
Transmit carrier frequency (Hz) (Note 4) F2
Carrier (F2) reference (Hz)
DG2 Coherent
1600
x
1469
DG2 Noncoherent Customer platform oscillator
Data modulation (Notes 1, 6) BPSK, SQPSK, or QPSK (refer to Appendix B
and Table 7-6)
Data format NRZ-L, NRZ-M, NRZ-S
Data rate restrictions (uncoded)
DG2
Total (Note 1) 1 kbps - 300 Mbps
I channel 1 kbps - 150 Mbps
Q channel 1 kbps - 150 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 7-16 450-SNUG
1:1
Single data source-single data channel NA
Dual data sources 1:1
Notes:
1. Customer platform data configurations, including specific data rate restrictions for coding and
formatting, are defined in Table 7-6 for TDRSS KuSA return service (refer also to Appendix B).
Unless otherwise stated, the data rate restrictions given in this table assume uncoded and NRZ
formatted signals.
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 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. The center frequency, f o , of the customer platform transmitter must be defined by the customer
MOC in its service specification code to an integral multiple of 10 Hz.
5. Unless otherwise noted, all data rate values are to be interpreted as data bit rates, and not as
data symbol rates.
6. Data rates and modulation schemes are based upon support through the KuSAR 225 MHz SN
ground terminal receivers. Other data rates and modulation schemes are possible through the
Ku-band return IF service. Please refer to paragraph 7.3.6 and contact GSFC Code 450 for
further information.
7.3.2.1 General Modulation and Coherent/Noncoherent Description
a. SQPN Modulation. SQPN modulation is used to prevent simultaneous
transitions of the I and Q PN sequences. For SQPN modulation, the PN chips
of the I and Q channel are staggered by a 1/2 chip. For data configurations that
use two PN spread channels, SQPN modulation must be used.
FR