International Telemetering Conference Proceedings / October 26-29, 1992 / Town and Country Hotel and Convention Center, San Diego, California / The Space Ground Link Subsystem (SGLS) provides full duplex communications for
commanding, tracking, telemetry and ranging between spacecraft and ground stations. The
up-link command signal is an S-Band carrier phase modulated with the frequency shift
keyed (FSK) command data. The command data format is a ternary (S, 1, 0) signal.
Command data rates of 1, 2, and 10 Kbps are used.
The method presented uses direct digital synthesis (DDS) to generate the SGLS command
data and clock signals. The ternary command data and clock signals are input to the
encoder, and an FSK subcarrier with an amplitude modulated clock is digitally generated.
The command data rate determines the frequencies of the S, 1, 0 tones. DDS ensures that
phase continuity will be maintained, and frequency stability will be determined by the
microprocessor crystal accuracy.
Frequency resolution can be maintained to within a few Hz from DC to over 2 MHZ. This
allows for the generation of the 1 and 2 Kbps command data formats as well as the newer
10 Kbps format. Additional formats could be accommodated through software
modifications. The use of digital technology provides for encoder self-testing and more
comprehensive error reporting.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/608937 |
| Date | 10 1900 |
| Creators | Gordon, Michael |
| Contributors | Cincinnati Electronics Corporation |
| Publisher | International Foundation for Telemetering |
| Source Sets | University of Arizona |
| Language | en_US |
| Detected Language | English |
| Type | text, Proceedings |
| Rights | Copyright © International Foundation for Telemetering |
| Relation | http://www.telemetry.org/ |
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