FPGA (field programmable gate array) based digital intermediate frequency coherent marine radar receiving and processing system

Abstract

The invention relates to the field of radar engineering and a radar system of intermediate frequency coherent, in particular to an FPGA (field programmable gate array) based digital intermediate frequency coherent marine radar receiving and processing system. The system comprises an intermediate frequency amplifier module connected with the output end of a receiver radio-frequency front-end, and is characterized by further comprising an A / D (analog / digital) sampling chip and an under-digital frequency conversion module, the under-digital frequency conversion module comprises digital-controlled oscillator, a low-pass filter and a digital decimation filter which are based on FPGA and are arranged in sequence; intermediate frequency power signals outputted by the receiver radio-frequency front-end are converted into voltage signals via the intermediate frequency amplifier module and then transmitted to the A / D sampling chip, and the voltage signals are acquired and transmitted to the under-digital frequency conversion module. The system is simple in structure and high in flexibility, image-frequency rejection ratio of I / Q signals is increased as compared with I / Q baseband signals respectively acquired with a simulation conversion method, and the system has the advantages of low drift, low distortion and the like, and useful information in return signals can be extracted to the greatest extent to be used for subsequent radar signal processing operations.

Description

Technical field [0001] The invention involves the field of radar engineering, especially the radar system of the intermediate frequency phase. Specifically, it is a FPGA -based ship radar digital medium -frequency phase intervision receiving processing system. Background technique [0002] Shipbuilding is a traditional radio navigation equipment that plays a role in shipping offshore, guiding ships to enter, leaving Hong Kong, narrow channel navigation, and spoils.Nowadays, ship radars can be used not only for ship navigation, but also for port management and marine remote sensing.At present, most of the domestic and foreign ship radar adopts a non -phase -ginseng pulse system. Because the frequency pulse frequency of the magnetic control oscillator is not stable enough, the phase of the phase between the pulse changes randomly.Phase information, only the target detection of the return on the back of the wave bag on the baseband was used to detect the target, which greatly rest...

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Problems solved by technology

However, there are many processing module chips and the structure is relatively complex, which makes the system design of the whole radar not compact enough; utility model patent [2] (ship navigation radar large dynamic range intermediate frequency digital module, application number: 201320044573.5, inventors: Ge Junxiang, Pan An , Lu Jianbin, etc.), described a large dynamic range intermediate frequency digital module for ship navigation radar, integrated intermediate frequency amplification, digital sampling and other parts into the same module by means of integrated circuits, the system is more concise

However, after the received signal is collected and directly sent to the FPGA through the interface for signal processing, only the amplitude information of the signal can be extracted but the phase information cannot be extracted, which determines that the radar cannot make full use of the Doppler information of the echo signal; the invention patent [3 ] (A radar receiving digital coherent processing system, application number: 201310024773.9, inventors: Xu Hongchun, Wang Jinjin), describes a radar receiving digital coherent processing system, adopts intermediate frequency direct digitization, and transmits main wave sample signal and intermediate frequency Convolution operation is performed on the echo digital signal to eliminate the influence of initial phase, frequency instability, and amplitude instability of the transmitted signal, and realize digital frequency stabilization and phase stabilization, adaptive frequency compensation, and receiving coherent processing

However, in the dual-channel mode, it is relatively complicated to ensure clock synchronization and I / Q signal amplitude and phase consistency.

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