Patent ID: 6968162
Filing Date: 2005-11-22
Classification: H04B

Abstract:
1. A satellite communication transmission control system which comprises one central station, a plurality of small aperture terminals, and one communication satellite serving as a repeater for the central station and the aperture terminals, and performs communication via a frequency division multiple access communication channel, wherein the central station comprises a modulator for transmitting via a common channel a signal for controlling/monitoring the small aperture terminals on the basis of a stable clock signal, and each of the aperture terminals comprises a modulator for modulating communication information from an information source, a transmission frequency converter for frequency-converting a modulated wave from the modulator into a carrier signal (modulated carrier), an antenna/RF device for exchanging signals between the aperture terminal and the central station, a reception frequency converter for frequency-converting a modulated carrier from the central station, a demodulator for demodulating a signal received via the common channel out of a frequency-converted received signal and outputting a reception clock, and a frequency comparator for detecting a frequency error of a local oscillator arranged in the transmission frequency converter by using a clock signal from the demodulator as a reference upon power-on operation, and generating a control signal for stopping transmission of the modulated carrier until the frequency error falls within a preset tolerance range.