Design of Digital IF Measuring Receiver with Auto-Tracking

This paper presents a new solution for measuring receiver of radio communication. Using the digital down converter technology of software radio, achieves the digital intermediate frequency (IF) circuit. And design a Nested-mixer DDS driving PLL microwave frequency synthesizer. This new type frequency synthesizer combines the advantages of DDS and phase locked loop (PLL), has high frequency resolution, fast frequency switching speed, low phase noise and convenient frequency adjustment. Take it as the first local oscillator in the measuring receiver. At the same time, utilizing the high-speed computing and powerful data processing ability of DSP, realizes the automatic measurement of the input signal amplitude, frequency, modulating frequency, frequency offset, and other indexes. Compared with the universal radio communication test instrument, this scheme can achieves a high performance index, while may significantly reduce the equipment volume, and there is a great help in expanding the instrument function.