ANTENNA ANGLE ERROR SIGNAL DETECTION SENSITIVITY CORRECTION CIRCUIT FOR AUTOMATICALLY TRACKING SATELLITE

摘要

PURPOSE:To maintain a better angle error signal detection sensitivity even with a low S/N ratio by detecting the amount of noise in a base band signal outputted from a receiver for the demodulation of data to correct the sensitivity according to the amount detected. CONSTITUTION:A flip flop 4 is supplied with a sampling timing (e) from a timing generator 8 as generated at a peak point position of a full-wave rectifier output signal (c) and when a square data (d) is inputted, an output of the flip flop is turned to a high level and when an output of a comparator 2 is at a low level, the low level is latched and outputted. Therefore, the more a noise level overlapping a demodulation base band signal (a) increases with a drop in S/N ratio, the more frequently the FF 4 latches the low level. A constant current circuit 5 generates a different value of current (g) according to a high or low level of the output (f) of the FF 4 to be outputted to an LPF 6. In other words, the current (g) is averaged with the LPF 6 having a proper time constant to obtain a signal (h) for correction. Base on a value of the signal (h), an amplification factor of an amplifier 7 is variably controlled to correct a detection sensitivity of an angle error signal, thereby obtaining a fixed correction angle error signal.