The Research And Design Of0.1～2.5GHz Simple Handheld Spectrum Analyzer Receiver Module

Handheld spectrum analyzer, a developing kind of economic and portable spectrum analyzer based upon a high-performance desktop spectrum analyzer and modern digital processing techniques, known as "frequency-domain oscilloscope", which is designed for field measurement. With the rapid development of wireless communication technology, the fast and convenient testing requirements becoming more and more intense in field measurement and measurements in other wireless communication products. The major instrument manufactures have developed their handheld spectrum analyzer one after another based on their own desktop instrument. Excepting the frequency range, the function of handheld spectrum analyzer is comparable to traditional desktop spectrum analyzer. With high performance but small size, light weight and easy to carry, Handheld spectrum analyzer is promising.In the thesis, we designed a0.1-2.5GHz receiver module of low-cost simple handheld spectrum analyzer. The module employs the low-IF Triple-conversion super-heterodyne structure, and use a switching frequency selection unit to reject the imaging frequency. SAW filters are used as the first IF filters and the second IF filter, that greatly reduced the filter size. The main tasks of this thesis are as follows:First, the feature and importance of the Frequency-domain measurement are introduced based on the time-domain characteristics and frequency-domain characteristics of the signal. The classification of the traditional desktop spectrum analyzer and basic components are introduced, the principle of each one, and the performance parameters of super-heterodyne spectrum analyzer are also introduced in this thesis.Secondly, according to the operating principle of the super-heterodyne spectrum analyzer and the economic and efficient demands of handheld spectrum analyzer, the method of whole design is completed. The process is described, and the budget and noise figure of the receiver module is also analyzed and simulated.Thirdly, the structure, design method and the selection of IC chips is discussed. The input attenuation, switching frequency selection, mixer, IF signal processing, video signal processing and micro-controller unit circuit is simulated by using ADS2009. Finally, the PCB design and hardware debugging are made in this paper. An overall picture of the receiver module is given. Moreover the test of the module is completed, including input VSWR, power gain,1dB compression, Noise figure and so on. The results of test prove that the design of this program fully meets the need of handheld spectrum analyzer.