The White Sands Complex (WSC) is located near Las Cruces, New Mexico and
includes two functionally identical satellite ground terminals. These terminals,
known as the White Sands Ground Terminal (WSGT) and the Second TDRSS Ground
Terminal (STGT), respectively. The ground terminals provide the hardware and
software necessary to ensure uninterrupted communications between the customer
spacecraft and the NISN interface to the
customer control center. Project Management and Systems Engineering for the WSC
are provided by the Space Network Project Office at the Goddard Space
Flight Center
White Sands Ground Terminal |
Second TDRSS Ground Terminal |
This portion of the TDRSS on-line information center includes information
regarding the ground segment of the Tracking and Data Relay Satellite System
(TDRSS).
Ground
Segment Functions
- Ground
Terminal Reference Architecture
- Ground
Terminal Subsystems
- Frequently
Asked Questions
The ground segment provides the following functions:
- Maintains each TDRS in a nominal (Ku Band) mode at all times and ensures
that all onboard systems are properly configured and functioning within
specified parameters.
- Transmits forward link traffic to each TDRS for transmission to the
designated customer spacecraft.
- Receives and processes customer spacecraft return link traffic from each
TDRS, formats and transmits the data to the NASCOM interface.
- Monitors state of health and control of the assigned TDRSs.
- Measures the range of each assigned TDRS relative to the ground terminal.
- Measures the closed loop (two-way) range and doppler or open loop
(one-way) doppler for customer spacecraft, and formats and transmits the
measured data to the NASCOM interface.
- Simulates customer spacecraft for the purpose of system performance
evaluation.
The WSC ground terminals are comprised of the following subsystems:
At the heart of the ground terminal are the Space to Ground Link Terminals
(SGLTs). Each station contains three SGLTs which operate autonomously to a large
degree. If a single SGLT is declared inoperative, then only the TDRS and
services supported by that SGLT are impacted. Each SGLT is capable of providing
four Single Access forward and return customer telecommunication
services and corresponding tracking services.
Two of the three SGLTs within each ground terminal can support five multiple
access (MA) return services (a total of 20 services between the two ground
terminals) and one forward MA service per MA-equipped SGLT (a total of four MA
forward services between the two ground terminals).
Space to Ground Link Terminal Architecture
Data Interface System
The Data Interface System (DIS) provides the secure operational interface with
the Data Services Management Center (DSMC) and provides automatic routing of customer data. The DIS is
able to configure itself in response to the customer service schedule.
The DIS also provides data quality monitoring, fault detection management, and
the interface to the NISN interface. The DIS also
provides the interfacility link between the ground terminals.
S-Band TT&C System
The S-band Tracking, Telemetry & Command System (STTCS) is used to provide
contingency support to a TDRS in the event of an SGLT failure which precludes it
from providing TT&C support to the TDRS. The STTCS is also used to provide
support to on orbit spare TDRSs.
Common Time and Frequency System
The Common Time and Frequency System (CTFS) generates and distributes highly
accurate and stable timing and frequency references to the ground terminal
elements. It provides the capability for time correlation with the United States
Naval Observatory using cesium beam frequency standards and associated signal
distribution equipment.
Software Maintenance and Training Facility
The Software Maintenance and Training Facility (SMTF) provides the capability
for on-site development, enhancement, testing and validating ground terminal
software and the training of operations staff and software maintenance
personnel. The SMTF ensures configuration management and software quality
assurance . The SMTF provides an environment similar to the actual ground
terminal operational environment for training and software testing with the use
of identical computer equipment. Console equipment and TDRS simulators are also
provided to support operator training.
Hardware Maintenance Depot
The Hardware Maintenance Depot (HMD) provides a maintenance and testing
capability for line replaceable units removed from operational equipment.
TDRSS Operations Control Center
The TDRSS Operations Control Center (TOCC) is the central operational control
facility within each ground terminal. The TOCC provides the interface for
controlling and monitoring the ground terminal systems.
Return to Space Network Information Center Homepage
