FPGA Design And Implementation Of Frequency Spectrum Detection System In Cognitive Radio Field

Through real-time detection wireless signals around in Cognitive radio, in order to use these free frequency band at the same time it does not affect the authorized user normal use of these band, can be better able to ease the tensions of run short in spectrum resources. Effectively improve the utilization rate of the spectrum. From the concept of cognitive we proposed a frequency detection solution used in frequency hopping communication.This paper introduced the basic concept of cognitive radio, as well as utilization rate of the spectrum, and then puts forward the application field of cognitive that communication frequency detection in frequency hopping communication.And then introduce the frequency detection algorithm in cognitive radio firstly such as AD sampling theorem, numeric rate signal processing theory, kinds of filter design, Digital down converter (DDC) and basic knowledge of FFT. These is the basic theorem of FPGA to implement these digital signal processing algorithm.numeric rate signal processing technology can keep signal not distortion and can convert down the signal rate this bring about the possibility the subsequent of the spectrum analysis and calculation. AD sampling theorem is the door of analog to digital, only after convert into digital signals then the digital processing algorithm can be used to deal with this analogy signal.FFT operation is the important step of spectrum detection which is used to covert time signal to frequency signal until then we can analysis this signal about it’s bandwidth take up And then introduced the PCI interface principle, this is data transmission channel, PCI with high-speed data transmission capacity.Secondly,gave the FPGA realize of these algorithm and interface,such an direct digital frequency synthesis (DDS), Digital down converter (DDC), fast Fourier transform (FFT) and FPGA realizing of PCI interface timing. According to the design we consider the specific requirements of the design then proposed the reasonable parameters.Both MATLAB simulation and modelsim simulation result are showed in algorithm part, both the simulation result proved the feasibility of the algorithm and the correctness of the FPGA realizing. State machines and timing design in quartus software timing screenshots are given.Finally, we proposed the solution about the hardware design, contain: AD sampling circuit design, FPGA module design, and power supply module design and PCI module design.All of these algorithm and the hardware realization complete the mission that receive wireless signal and signal amplification, AD sampling, extraction filtering, FFT operation and then PCI interface transmitting the data of the signal detection out all of these make up a system. At the same time PCI transmission control command which control detection system parameters from the PC. Through the design and practical application that proved the feasibility of the design. Also provides a basis solution for realization of the spectrum detection in concept of cognitive radio. The design parameter is simple to modify, easy to upgrade which provides a good basis module for next step of the system integrated.