Abstract: A method and apparatus are provided for determining the fidelity of one or more communications channels with high efficiency and resolution with particularly advantageous application to digital communications in a radio communications environment where portable radios roaming across multiple RF site coverage areas strive to monitor the optimal control channel having the highest signal fidelity under current receiving conditions. The radio collects signal fidelity information for alternative communications channel in very short time intervals without missing important messages on a communications channel currently being monitored by that radio. Signal fidelity of the alternative communications channel is calculated without the radio being synchronized either at a digital bit or frame level to the alternative communications channel. The fidelity calculation provides information both about the accuracy (i.e., the digital value of a received digital pulse) and the quality (i.e.

Abstract: An extremely compact, full featured portable radio architecture conserves power by allowing a processor to sleep except when it needs to perform tasks. A lower power processor which acts principally as an interrupt controller but which performs other functions as well (e.g., tone decode, synthesizer lock monitoring, etc.) so the main processor can sleep as much as possible and yet is assured of being awoken promptly when its processing power is required. The resulting portable radio has extremely low power consumption (e.g., on the order of 75 milliamperes during trunked mode operation)--thereby permitting even a relatively small battery pack to provide nearly 8 hours of continuous operation. The portable radio with battery is small and lightweight enough to fit into a front shirt pocket.