Abstract: A portable real-time monitoring system for field testing and troubleshooting a cellular telephone network, paging network, or mobile radio system employs a user friendly interface between a user and a scanning radio receiver which displays, monitors and stores parameters related to real-time performance. A portable all-band radio receiver capable of receiving cellular and paging frequencies is connected to a computer, such as, for example, a lap-top computer suitable for mobile operation at remote sites, personal computer (PC) or workstation. An interface circuit is installed within the radio receiver which taps available signals within the receiver as well as allows the computer to control the receiver frequency selection, band designation and demodulation setting. The interface hardware and microcode cooperate to process and decode received signals according to cellular and paging network industry standards.