Определение области влияния передающего радиомодема на уровень сигналов ГНСС на спутниковом приемнике
Аннотация. Приведены результаты экспериментов по оценке отношения сигнал/шум на контрольных приемниках, расположенных на разных расстояниях от источника сигнала. Для радиомодема, передающего сигнал с мощностью 1 Вт, расстояние действия гармоник не превышает 15 м. Показана зависимость того, как уменьшение мощности передающего модема связано с влиянием на отношение сигнал/шум.
Ключевые слова: ГНСС, RTK, отношение сигнал/шум, радиомодем, гармоники основного сигнала, спутниковый сигнал, GNSS, SNR, UHF radio-modem, harmonics, satellite signals
Determination of the territory of the influence of UHF transmitting modem to GNSS signals quality in satellite receiver
Summary. The article describes the problem of influence the 3rd and the 4th harmonics of the radio modem signal to satellite receivers. When using the frequency from range 400-420 MHz of the transmitting radio modem, the 3rd and the 4th harmonics of this signal can fall into the GNSS (Global Navigation Satellite System) operation band and decrease the satellites signal quality. This phenomenon is observed not only on the base receiver, inside which the transmitting radio modem is located, but also extends to some surrounding territory. A theoretical analysis of this problem is shown in this paper. The signal-to-noise ratio (SNR) is selected as the criterion of the satellites signal quality. The article discusses the signal-to-noise ratio in relation to satellite geodetic receivers. In order to determine the area of influence of harmonics, experiments were performed. In these experiments, control receivers were located at different distances from the base receiver. UHF radio-modem was located inside base satellite receiver. It was measured how the SNR changes at the control receiver when the modem is turned on at the base receiver for transmission. The power of the transmitting modem during the tests varied from 1 W to 20 mW. All tests were performed at frequencies 401, 409, 415 MHz. The results of the experiments showed that the significant effect of the harmonics of the radio modem signal extends no more than 15 meters from the signal source. Reducing the signal power of the transmitting modem decreases the effect on the SNR at the control receivers.