Performance Analysis of Long Loop PLL in Real Time Measurement of Received E_b/N_o and Carrier Recovery from PSK Modulated Signals of Remote Sensing Satellites

摘要

Long loop carrier tracking phase locked loop is used for continuous monitor and measurement of E_b/N_o received from a remote sensing satellite during the live satellite pass thus enabling the near accurate assessment of the feal time performance and quality analysis of the received signals. The configuration is also used to recover the coherent carrier with improved lock acquisition threshold, which is useful while demodulating very low data rates signals with very low E_b/N_o ratios. The total circuitry hence becomes the part of the demodulator unit of a multi-mission remote sensing satellite ground station. This paper analyses the performance of this long loop PLL configuration and establishes its superiority over conventional methods of carrier recovery and online E_b/N_o measurement techniques. The circuit has been implemented, using this configuration, in the multi-mission PSK demodulator and has been tested successfully. The unit meets the requirements of a multi-mission ground station expected to track and receive various low earth orbiting remote sensing satellites transmitting a wide range of data rates with very high Doppler offsets.