The earth station can measure the round-trip time and frequency of the signal and use it to calculate and correct the Doppler shift. As it goes away, the frequency appears to be lowered. As a satellite approaches, the frequency appears raised relative to the actual transmission frequency. The curve of Doppler-Shift and Doppler-Rate when the Doppler effect is severe is shown in Figure 1. Another common method is to use a feedback loop, where the earth station sends a signal to the satellite and receives a confirmation signal back from the satellite. Measuring the Doppler Shift is a satellite tracking technique for determining the distance between the satellite and the receiver at the time of closest approach as well as the time itself. Exact analytical expressions for Doppler shift and elevation angle as a function of perigee time of the ground-station are also presented. In the satellite communication, the Doppler shift will be much larger with the maximum Doppler considered in LTE specifications. Then, the earth station can adjust its transmitter and receiver frequencies accordingly to match the Doppler shift. A theoretical and experimental study of Doppler correction strategies for elliptical orbit satellite communications is presented.
In applications where you have these sort of dynamics, you typically cant mitigate it much, so youre left with building a receiver that tolerates the effects. The earth station can measure the frequency of the received reference signal and compare it with the expected frequency to determine the Doppler shift. The high radial velocity of the satellite toward the receiver will cause a Doppler shift, and any change in that velocity caused by its orbit will cause that shift to change over time. With the development of optical space communications, a global space-based optical backbone network is currently proposed by using broadband laser. One common method is to use a reference signal, such as a beacon or a pilot tone, that is transmitted by the satellite at a known frequency. navigation system has greatly changed the mode of travel, communication. Doppler shift can be measured and compensated by various methods, depending on the type and complexity of the SATCOM system. Intersatellite Doppler Shift Simulation Analysis of Laser Frequency Band.
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