Research On Error Detection And Digital Signal Processing Of W-band LFMCW Radar Reflected Power Canceller

In LFMCW radars, the RF cancellation technology is an important technology which can solve the signal leakage problem of continuous wave radars, and the error detection module is key module that affects T/R module to achieve the function of the RF cancellation. The module use mixer to demodulate the residual error signal which contains the leak signal in the receiver channel, then extracts its amplitude and phase information, finally the obtained information will be sent to the digital signal processing module. After the high-speed and real-time signal processing by the DSP module to get the two base-band signal “I” and “Q”. The two base-band signal be used to control the work of the vector modulator to achieve perfect cancellation of the leak signal. In order to avoid the phenomenon of false zero-IF frequency in single-conversion, this paper uses double-conversion technology in W-band, and through hybrid integrated circuit to achieve the design of the error detection and digital signal processing module.In this paper, the first chapter proposes the functions of the error detection and digital signal processing module. Then we make a compare on the study trends of related design between domestic and overseas. At last, the structure of this paper is stated. In the second chapter, we put forward two implementation scheme of the error detection module, including direct-conversion and double-conversion, and compared its working principle. Then we give the principle and the algorithm of digital signal processing module which have validated with DSP development board. The third chapter simply introduces the theory of transmission line, then design the waveguide-to-microstrip transition circuit and the orthogonal power dividers based on these theory. Finally combining the results of simulation and the target, we chose the passive circuits as we needed. The fourth chapter introduces the working principle and technical indicator of mixer and amplifier in the module. Then we choose the corresponding millimeter wave monolithic circuit to process and test. In the need of band, the tests show that the conversion loss of gMDR0013 mixer is less than 13 dB and image rejection is about 20 dB. The gMBR0011 mixer’s conversion loss is 15 dB. Then we introduce the theory of crystal oscillator, and design, process 1MHz heterodyne circuit. The results show that the two heterodyne signals’ amplitude error is less than 0.3dB, the phase error is less than 2.8 degrees. Finally we design and produce the whole circuit of the error detection module on a on a microstrip substrate which have test and analysis. In the fifth chapter, we summarize the work of this paper, and put forward the expectations for the next step of this work.