TERRAIN AND IONOSPHERIC EFFECTS ON ELT TRANSMISSIONS TO A SARSAT SPACECRAFT

Authors
  1. Palmer, F.H.
Corporate Authors
Communications Research Centre, Ottawa ONT (CAN)
Abstract
In order to carry out an RF link analysis for a Search and Rescue Satellite System (SARSAT) it is necessary to determine the effects of local terrain and surface cover, and of the ionosphere, on emergency locator transmitter (ELT) transmissions. The report summarizes the results of a study carried out by the Communications Research Centre (CRC) in order to assess the probable magnitude of such effects. It is concluded that signal attenuation and fading of an ELT signal, due to local topography and surface cover, probably do not exceed about 6 dB at spacecraft elevations above the 20 degrees, except possibly in Pacific Coast forest areas. Considerable fading of the 121.5 MHz frequency may be caused by the night-time high-latitude ionosphere. A major area of uncertainty is the actual radiation pattern of an ELT under "crash" conditions. An appropriate measurement program of such patterns is suggested.
Report Number
1324 —
Date of publication
15 May 1979
Number of Pages
12
DSTKIM No
79-02231
CANDIS No
86579
Format(s):
Originator's fiche received by DSIS;Hardcopy

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