TRACKING RECEIVER NOISE BANDWIDTH SELECTION

Abstract

The selection of the Intermediate Frequency (IF) bandwidth filter for a data receiver for processing PCM data is based on using a peak deviation of 0.35 times the bit rate. The optimum IF bandwidth filter is equal to the bit rate. An IF bandwidth filter of 1.5 times the bit rate degrades the data by approximately 0.7 dB. The selection of the IF bandwidth filter for tracking receivers is based on the narrowest “noise bandwidth” that will yield the best system sensitivity. In some cases the noise bandwidth of the tracking receiver is the same as the IF bandwidth of the data receiver because it is the same receiver. If this is the case, the PCM bit rate determines the IF bandwidth and establishes the system sensitivity. With increasing bit rates and increased transmitter stability characteristics, the IF bandwidth filter selection criteria for a tracking receiver must include system sensitivity considerations. The tracking receiver IF bandwidth filter selection criteria should also be based on the narrowest IF bandwidth that will not cause the tracking errors to be masked by high bit rates and alter the pedestal dynamic response. This paper describes a selection criteria for a tracking receiver IF bandwidth filter based on measurements of the tracking error signals versus antenna pedestal dynamic response. Different IF bandwidth filters for low and high bit rates were used.