The New Data Subsystem (NDS) operates in conjunction with the STC to support orbiting satellites, utilizing the software described in Appendix B. The data subsystem performs (1) automatic processing, (2) Monitoring, and (3) controlling functions for satellite acquisition and tracking, telemetry data processing, and command data processing during prepass, realtime, and postpass operations. In addition, control and configuration of other subsystems at KTS are provided, together with checkout of station functions. Figure 3-49 is a functional block diagram of the subsystem. Typically the system operation relating to the NDS is as follows:

1. Satellite prepass messages, predicted acquisition data, and commands originate at the STC where they are encrypted and transmitted over teletype lines to the tracking station. The incoming data is routed through the communications subsystem, where it is deciphered and transferred to the communications buffer.

2. Prior to acquiring a satellite, the operation controller at the station operator's console determines whether satellite acquisition is to be controlled manually or by the computer. When acquiring manually, antenna operation is controlled from either the TT&C or 200 MHz autotracker antenna areas designated by the operations controller. When acquisition is controlled automatically, the computer transfers the predicted antenna axis data and satellite range to the input/output buffer, where it is stored until required by the digital slave bus or the digital-to-syncro converter, applied to the slave bus switching unit, and made available to the antenna in order to acquire the satellite. Sequence and timing, as well as operation of the data handling equipment, are controlled by the computer program.

3. Actual antenna position data from the antenna in use is sensed by the remote digital terminal, converted from Gray to binary form, and routed through the intermediate equipment to the computer, where it is interpolated and used to drive other antennas supporting the mission.

4. When the satellite is acquired, the tracking station may begin transmitting commands to the satellite and receiving back telemetry data. Analog commands in the form of relay closures are routed under computer control via the command buffer to one of two analog transmitters. The commands, transmitted in tone form, are monitored and sent back to the input/output buffer as an echo check for comparison against the command received and returned by the satellite. A command verification check is made both by the satellite and the ground station to assure correct formatting of the commands.

5. Digital commands are formatted by the computer according to the requirements of the satellite. The commands are packed into the command buffer and transferred to the selected transmitter. Digital commands are transmitted by time-position modulating binary 1's and 0's. Each digital command word pulse is preceded by a new word pulse, which is also is time-position modulated. Echo and command verification checks are made on the digital commands.

6. The data handling subsystem processes both FM/FM telemetry and pulse coded modulation (PCM) telemetry. The demodulated and decommutated satellite telemetry data from the FM/FM telemetry subsystem is applied to the telemetry data processor which processes the data and transfer it, through the telemetry data processor buffer, to the computer complex. Time reference signals and data tagging are also introduced at the telemetry data processor buffer. The data and timing information is then routed through a computer dual access buffer to the computer for processing and evaluation.

7. The computer receives decommutated PCM telemetry data from two remote PCM decommutators. The actual data transfer is accomplished through the interface provided by the computer dual access drivers. The computer is capable of receiving the data either simultaneously or independently, at rates inclusive from 0 to 125,000 30-bit word transfers per second. In addition to processing the received data, the computer also supplies data and instructions to the PCM decommutators in accordance with the computer program.