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Special semaphore scheme for uhf spacecraft communications
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Butman, Stanley Ilott, Peter Satorius, Edgar |
| Copyright Year | 2006 |
| Description | A semaphore scheme has been devised to satisfy a requirement to enable ultrahigh- frequency (UHF) radio communication between a spacecraft descending from orbit to a landing on Mars and a spacecraft, in orbit about Mars, that relays communications between Earth and the lander spacecraft. There are also two subsidiary requirements: (1) to use UHF transceivers, built and qualified for operation aboard the spacecraft that operate with residual-carrier binary phase-shift-keying (BPSK) modulation at a selectable data rate of 8, 32, 128, or 256 kb/s; and (2) to enable low-rate signaling even when received signals become so weak as to prevent communication at the minimum BPSK rate of 8 kHz. The scheme involves exploitation of Manchester encoding, which is used in conjunction with residual-carrier modulation to aid the carrier-tracking loop. By choosing various sequences of 1s, 0s, or 1s alternating with 0s to be fed to the residual-carrier modulator, one would cause the modulator to generate sidebands at a fundamental frequency of 4 or 8 kHz and harmonics thereof. These sidebands would constitute the desired semaphores. In reception, the semaphores would be detected by a software demodulator. |
| File Size | 540705 |
| Page Count | 1 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20110013622 |
| Archival Resource Key | ark:/13960/t53f9qs1g |
| Language | English |
| Publisher Date | 2006-12-01 |
| Access Restriction | Open |
| Subject Keyword | Man/system Technology And Life Support Transmitter Receivers Sidebands Spacecraft Orbits Rates Per Time Ultrahigh Frequencies Spacecraft Communication Sequencing Modulators Mars Landing Radio Communication Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Technical Report |
