Research On Radio Wave Propagation Characteristic Of Spacecraft Telemetry Receiving On The Sea

Radio propagation in ocean wireless channel is different from the way in land. The ocean surface is roughness which is conformed to some statistical law. And in electromagnetic theory the dielectric of sea water is not constant. After the reflection from ocean surfaces, the amplitude and phase of radio wave can be both changed. Without held up in the wide sea area, the reflection wave can be a strong interference to the direct wave, which is called multipath fading effects.The PCM/FM system is often used in aerospace telemetry system. And the code rate of PCM signal is higher and higher in order to meet the needs of information transmission. It is known that the multipath channel is sensitive to high speed signal. So it is necessary to make an analysis for the characteristics of telemetry sea wireless channel.Based on the dielectric property and fractal theory, the reflection characteristic about sea water is discussed in this paper. By multipath channel modeling, the distribution of reflection coefficient and time delay near the survey ship is obtained. And the analysis for channel characteristic is also made, especially at low elevation angle.