Study And Design Of Synthetic Test System For Frequency Characteristics

With the rapid development of economic measuring instrument manufacturing, thetechnology of the network analyzer and the impedance analyzer used to measure thefrequency characteristics develop very fast. Traditional frequency characteristics of the testeris not only expensive, and do not have the phase frequency characteristics. Now the tendencyis small, wide bandwidth, intelligent, multi-use direction. In recent years, with advances intechnology, the frequency is more and more depth, in-depth study is based on the researchprojects. The design is based on the principle of the frequency sweeping method; incorporatethe measurement of frequency response and impedance. On the premise of thecost-performance being fully considered, it realizes the double function of the measurementof frequency response and impedance. The core of the frequency sweeping method is thedesign of swept signal source and the signal source’s quality may directly influence themeasuring accuracy. The output signal of DDS swept signal source has the advantages ofhigh frequency accuracy and good stability, so the design takes the Microcontroller as thecore, the sweep signal is generated by DDS swept signal source, and assisted by impedancemeasuring auxiliary circuit, detecting circuit and man-machine interface circuit to measurethe frequency characteristics of every frequency point. According to the different chosenmeasurement mode, the system could switch the access point of the sweep signal, choosing toinput the signal into the network under test or the impedance measuring auxiliary circuit. Bythe amplitude and phase relationship of the output and input signal, it can figure out thefrequency response of the network under test or the impedance of the electronic componentbeing measured. The design uses LCD as the display unit to compose the favorableman-machine.