Design And Implementation Of The Wave For Spectrum Analysis On Software-defined Radio Platform

As the basic measuring tool in frequency domain, spectrum analyzer has vital significance in scientific research and production. But in recent years, with the development of wireless communication, the demand and using of spectrum resource have increased rapidly and this makes the spectrum environment more complex. Thus, it resquests the spectrum analyzer be more flexibility, configurability and open. Those requirements just meet the ideas of software-defined radio technology.The basic idea of software-defined radio is to implement various businesses and meet different needs on a set of standardized, modular and general hardware platform. Modern spectrum analyzer has started using this structure which includes simulation radio frequency(RF) receiver and digital intermediate frequency(IF) processing system. This structure can achieve high frequency resolution and implement more measuring functions. In the structure, the key to realize high performance spectrum analysis is the digital IF processing system.The purpose of this paper is to give a digital IF processing scheme for the spectrum analysis and verify its feasibility on software-defined radio platform. Thus, it can effectively simulate the actual spectrum analyzer, and can reduce research costs by using the general hardware platform. In the scheme, the digital IF processing system for the spectrum analysis is divided into several modules, including digital mixer module that moves IF signal to baseband, cascade integral comb filter module and cascade half band filter modulse that can reduce spectrum aliasing and the sampling rate of signal, spectrum calculation module that calculate spectrum of the discrete signal, parameters control module that controls sequence and parameters in system.The scheme uses the signal that center frequency is 70 MHz, sampling rate is 230.4MSPS as inputing, needs to achieve frequency resolution bandwidth range from 30 Hz to 30 kHz, and choses FPGA chip Xilinx Virtex6 xc6vsx315 t that owns abundant resources as the digital IF processing chip. The test result on software-defined radio platform shows: each module can normally work; the dynamic range of the IF scheme can reach 65 dB; the error of the actual frequency resolution is within the analysis range.