Studies on variation of GNSS signal strengths from India

64-71Commercial Global Navigation Satellite System (GNSS) receivers provide the measure of received satellite signal strength in terms of Signal to Noise ratio (SNR) or Carrier to Noise ratio (C/N0), through in many cases the terms are used interchangeably. The received signal strength affects the receiver performance, as this is one of the measures of usability of satellites for position solution purpose. GNSS signals pass through and are affected by atmosphere, therefore the signal strength values were also used for atmospheric research purposes. This paper presents the results of long-term studies on GPS, GLONASS and Galileo signal strengths and their variation patterns using data from a commercial multi-GNSS receiver operating from Burdwan situated in eastern India. It may be observed that generally signal strength values increase with increasing elevation angle of satellites with decreasing fluctuations and the values saturate above certain elevation angle. The three constellations offer slightly different signal strengths and new generation Galileo and GLONASS satellites provide higher satellite signal strengths. The results would be useful in understanding the usability of GNSS signals for various purposes