Development and testing of a satellite-aided distress alerting system
Abstract
The distress signaling system described in this paper is designed to provide reliable detection of distress messages in a matter of minutes for ships and aircraft in oceanic regions. The system employs low-power (on the order of 10 watts e.i.r.p.) spread spectrum transmissions via existing and planned geostationary satellites and their earth stations. The use of such low power levels raises the question of immunity to unintentional interference, which has been observed at e.i.r.p. levels of up to 32 dBW in the mobile satellite bands. To survive these conditions, a spread spectrum signaling approach is proposed. The receiver design utilizes matched filters based on charge transfer devices, as well as off-line digital processing. Engineering models of the receiver and transmitter have been developed and tested through the Pacific Marisat, using a single earth station for both the up-link and the down-link. Because the receiver measures the predetection SNR and rejects all messages below a threshold corresponding to an error probability of 0.00001, it was possible to demonstrate error-free reception under all test conditions, with a high percentage of the messages passing the SNR threshold for most test conditions.
- Publication:
-
5th International Conference on Digital Satellite Communications
- Pub Date:
- 1981
- Bibcode:
- 1981dsc..conf..175F
- Keywords:
-
- Emergencies;
- Rescue Operations;
- Satellite Networks;
- Signal Reception;
- Spacecraft Communication;
- Matched Filters;
- Performance Tests;
- Ships;
- Spread Spectrum Transmission;
- Synchronous Satellites;
- Systems Engineering;
- Communications and Radar