A Continuous Measurement of G/T for Satellite Broadcasting Receiving Systems

Yuliman PURWANTO  Yasutaka OGAWA  Manabu OHMIYA  Kiyohiko ITOH  

IEICE TRANSACTIONS on Communications   Vol.E75-B   No.8   pp.767-774
Publication Date: 1992/08/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Satellite Communication
measurement,  G/T,  satellite-broadcasting,  receiver,  antenna,  

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Weather conditions affect the performance of satellite broadcasting receiving systems. For example, snow accretion on antennas degrades G/T seriously because it reduces received signal power and also can increase antenna noise. We need a continuous measurement of G/T to evaluate the effect of the weather conditions to the satellite broadcasting receiving systems. However, a conventional method cannot perform the continuous measurement because the antenna under test must be oriented in a specific direction (to the zenith) to obtain a noise level in a satellite broadcasting channel. This paper presents the continuous measurement of G/T for the satellite broadcasting receiving systems. We describe details of the measurement method. In our measurement system, a standard antenna is placed at the inside of a room in order to prevent the weather conditions from affecting the gain of the standard antenna. The power flux density at the inside of the room is different from that at the outside where the antennas under test are placed. Employing the effective gain of the standard antenna, we take the difference of the power flux density into account. Moreover, we propose a method to estimate the noise level in the satellite broadcasting channel from the values at the outside of the channel, and clarify the accuracy of the noise estimation. Then, we show measurement results of the G/T values for several receiving systems. From these results, we show that the G/T measurement system has high precision. Also, from the specifications of the antenna gain and typical values of the noise figure, it is expected that the measurement system has a sufficient accuracy.