But to the CW pulse signal with changing carrier wave frequency, common filter cannot achieve narrowband filter, whereas broadband filter cannot reach the request of the signal-noiseratio.
From signaltonoiseratio analysis of the modulation signal, we choose the phase modulation method as the suitable carrier modulation for the twisted-pair.
Their main function is to simulate the satellite signal from the really satellite on the satellite orbit through changing code phase, Doppler shift, carrier and signal-to-noiseratio.