SN User's Guide - ESC Home - NASA

d. After symbol/decoder and symbol/deinterleaver/decoder synchronization is
achieved, MA return service channel data is available at the SN ground terminal
interface.
e. To minimize return data loss, it is recommended that the customer platform
transmit idle pattern on its data channels until after it has observed (via the user
performance data (UPD) data) that the SN ground terminal has completed all of
its data channel signal acquisition processes.
f. Requirements for bit error probability and symbol slipping take effect at the time
decoder synchronization is achieved.
NOTE:
Acquisition times will be reduced when data and symbol
transition density values are higher than the minimum
required.
5.3.3.2 Bit Error Rate (BER)
Table 5-8 provides Prec equations that will result in a customer achieving a BER of 10 -5
for TDRSS compatible signals. The BER Prec equations are applicable for either
powered (SMAR only) or non-powered flight dynamics and the following conditions:
a. Data Encoding. Convolutional encoding (rate 1/2 or rate 1/3 (SMAR only))
should be used for all customer platform MA transmissions both to minimize Prec
and as an RFI mitigation technique. Detailed coding design is described in
Appendix B. Reed-Solomon decoding is available to WDISC customers; typical
performance is given in Appendix K.
NOTE:
For all configurations and modes, the SN is capable of
providing SMAR support of uncoded links; however,
performance is not guaranteed in RFI and must be
coordinated with GSFC Code 450.
b. Received Power. Prec is in units of dBW. The customer project, in determining
its design requirements for minimum customer spacecraft EIRP, must take into
account customer platform transmit antenna pointing losses, the space loss
between the customer platform and the TDRS, and the polarization loss
incurred between the customer platform transmit antenna and the TDRS
receive antenna. The maximum TDRS receive antenna axial ratio is given in
Table 5-8 (also refer to Appendix A). For DG1 and DG2 services, the following
conditions apply:
1. Balanced Power Single Data Source-Identical Data on the I and Q
Channels (DG1 mode 1 and 2 only). For a customer platform
synchronously transmitting identical data on the I and Q channels (single
data source – identical data) with a balanced I and Q channel power
Revision 10 5-27 450-SNUG