A Study on Modulation/Demodulation for a Satellite Analog Telemetry System,
FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AFB OH
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The analog telemetry subcarrier channel for satellites employs the FSK modulation scheme. The primary information transmitted is the time of the pulse front. However, the time at which a pulse appears varies. Therefore, it is similar to the PPM-FM modulation scheme. In the demodulation process, the bandwidth is increased to improve the time resolution. However, increasing bandwidth will lower the signal-to-noise ratio of the channel and the probability of making an error is greatly increased. Hence, a suitable bandwidth must be selected. This paper discusses the principle and advantages of the cross level detection method. It is better than the fixed level detection method in time resolution and decision failure probability. Chinese translations.