SN User's Guide - ESC Home - NASA

3.1 General
Section 3. Services Available to Customers
The SN along with its supporting elements can provide various services to customers
including: telecommunications, tracking, testing, analysis, and data distribution/
processing services.
3.2 Telecommunications Services
Several types of telecommunications services are simultaneously available to
customers. The type of telecommunications service selected is determined by the data
rate required, duration of service period, and customer platform telecommunications
system design. The two primary telecommunications services are termed Multiple
Access and Single Access. The MA services are available at S-band and the SA
services are available at S-band, Ku-band, and Ka-band (F8-F10 and K, L, M only)
frequencies.
The SN can provide any of the following services:
a. A forward service, defined as the communication path that generally originates
at the customer control center and is routed through WSC or GRGT to the
TDRS to the customer platform.
b. A return service, defined as the communication path that generally originates at
the customer platform and is routed through the TDRS to WSC or GRGT back
to the customer control center and/or data acquisition location.
c. Both forward and return services simultaneously.
The forward service is typically utilized for customer platform commanding and may
include a separate ranging channel for use in tracking services. Forward service data
rates are variable depending on the forward service type, which are S-band Multiple
Access Forward (MAF) through TDRS F3 – F7, S-band Multiple Access Forward
(SMAF) through TDRS F8 – F10 (and K, L, M once launched), S-band Single Access
Forward (SSAF), Ku-band Single Access Forward (KuSAF), and Ka-band Single
Access Forward (KaSAF) through TDRS F8 – F10 (and K, L, M once launched). Table
3-1 provides an overview of the TDRSS forward service characteristics.
The return service is typically utilized for the return of science data and customer
platform status information. The return service consists of up to two channels, which
may include a pseudorandom noise (PN) code for use in ranging services and to reduce
power flux density. Similar to the forward service, return service data rates are variable
depending on the return service type, which are S-band Multiple Access Return (SMAR)
through TDRS F3-F7, SMAR through TDRS F8 – F10 (and K, L, M once launched), S-
Revision 10 3-1 450-SNUG