| In modern war, the radar has become the indispensable technical to investigateand detection object. So the performance of the ray of good seriously affects theunderstanding of target detection, judgment. By the theory of radar signal can be known,the radar performance has huge close relationship between the signal parameters. Linearfrequency modulated continuous wave radar transmitter linear FM signal which caneffectively increase the signal bandwidth, and achieve high frequency resolution, andthere is no distance blind spots and other advantages.So the LFM-CW radar has beenwidely used.First in this paper, linear frequency modulation signal is directly produced byDDS and on this basis, through a multiplier and inverter technology successfullygenerated X-band chirp signal bandwidth of300MHz, stepping time of8ns, frequencyresolution achieve300Hz. This article mainly introduced the application of DDS chipAD9858produced the principle of linear FM signal, process and methods, Again, thetransceiver principle, structure and related briefly in this paper, and designed a zero-IFreceiver system accounting related indicators, given the design diagram and PCB layout,cavity design and so on. Then at the commissioning of the entire system，we designand debugging features filters, solve the flatness of the transmitting and receivingsignals and the spurious.Finally introduces the working principle of phase-locked loop(PLL) technology, phase noise and spurious control. And then we use chip ADF410Xseries to generate DDS clock signal required by the desired and upper frequency of theLO signal. The phase noise satisfies the requirement of technical indicators.At the end of the article, this project are summarized, and analyzed the problemsin the debugging process, put forward the solution, make the system meet therequirements of technical indicators, and work normal，Finally, we complete the X-bandsurveillance radar transceiver front-end one and it has been delivered. |
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