The Effect of Frequency Tracking, the Use of a Phase-Lock Loop, and Predicted Tracking on Receiver Sensitivity

Frequency tracking, the phase-lock loop, and predicted tracking, when used to improve the effectiveness of radio receivers in the tracking of earth satellites are compared. The techniques are evaluated in terms of their effect on receiver sensitivity. Sensitivity is defined as the input signal power required to produce the output signal to noise ratio deemed necessary, by the system designer, for detection. The detection bandwidth for each technique is smaller than that of the conventional receiver. By using the smaller bandwidth, much extraneous noise is removed and the output signal to noise ratio is improved. A lower value of input signal power is required to produce the output signal to noise ratio and the sensitivity is increased. The detection bandwidths for frequency tracking and the phase-lock loop are nearly the same. Because of the lower threshold of the phase-lock loop, the receiver sensitivity is greater by two orders of magnitude than that of frequency tracking. Prediction tracking is a form of correlation detection which makes more effective use of the reduced detection bandwidth. When used in conjunction with the other two techniques, the sensitivity is increased by a other order of magnitude.