The Implement Of Communication Signals Frequency Scanning And Measurement

Typically, the communication signals occupy high-frequency(HF), very high frequency(VHF) and ultra-high frequency(UHF) bands in the electromagnetic spectrum. Also on the lower frequencies, emergency communication links work in very low frequency(VLF) and low frequency(LF). On the higher frequencies, satellites communication can work in the X-band and K-band. The U.S. military defense satellites communication systems even work in the 20 GHz and 44 GHz.Typically, the working frequency range of a communication detective system is required to be 2~1000MHz. Faced with such large frequency coverage, it’s difficult to achieve full probability receiving. The usual approach is to sweep. Frequency measurement is the basic tasks that must be completed by almost all receiver systems. In the digital domain, frequency measurement algorithms have advantages of flexible and high precision.With the development of field-programmable gate array(FPGA) technology, the logic gate arrays and modules integrated on FPGA have been increased. FPGA can be used to complete more and more functionality. Its high-speed and high integration advantages make it be widely used in real-time or near real-time processing applications. Based on FPGA and PC, the article builds a system platform to accomplish frequency scanning and measurement of communication signal. And it focuses on the design of the various components of the system and the third generation host interface bus(PCIE). At last, it completes the design, implementation and verification of the entire system. The variable bandwidth digital down conversion, variable point fast Fourier transform(FFT), digital frequency measurement and the hardware part of the host interface modules are implemented on FPGA. Hardware drivers and PC applications are achieved on PC. The entire system can be controlled by the interface of PC application to scan maximum frequency range 20MHz~3.6GHz with minimal 250 KHz, maximum 20 MHz stepping bandwidth and to measure the signal frequency. Scanning results and frequency measurement results uploaded via the host interface to the PC interface for display.