All of the single sideband systems currently being considered for the land mobile radio service transmit a pilot tone in addition to the wanted information. The pilot is required in the receiver for automatic gain control and automatic frequency control. In particular, a phase-locked loop is often employed to perform receiver frequency control. This thesis begins by presenting background information on phase-locked receiver design and the problem caused by excess time delay introduced into the loop of a conventional phaselocked receiver. A novel phase-locked loop configuration is introduced and shown to overcome the effects of the excess time delay. The same technique is shown to greatly improve the adjacent channel selectivity performance of a phase-locked receiver. Random phase and amplitude variations are impressed upon a signal transmitted through the land mobile multipath environment. After discussing several models of the propagation medium, some of the limitations it imposes on phase-locked SSB receiver performance are introduced.
|Date of Award||1983|