Doppler centroid estimation method based on field programmable gate array (FPGA)

Abstract

The invention discloses a Doppler centroid estimation method based on a field programmable gate array (FPGA) and mainly solves the problems of a large amount of occupied resources and slow processing speed in estimation of Doppler centroid in the prior art. The realization method comprises the following steps that: a dislocation vector is generated by a first-order register from single distance unit orientation continuous data; conjugate multiplication is performed on the single distance unit orientation continuous data and the dislocation vector by calling a multiplying unit in the FPGA; accumulation and averaging are performed on the result obtained from the multiplication to obtain an autocorrelation value R of the single distance unit orientation continuous data; cosine value of R phase angle is calculated according to the autocorrelation value R; the cosine value of R phase angle of the autocorrelation value R is taken as a lookup address to perform arc cosine lookup to obtain the phase angle of the autocorrelation value R; the phase angle of the autocorrelation value R is corrected to obtain a Doppler centroid estimation result of the single distance unit orientation continuous data. The method lowers system power consumption, improves processing speed and can be used for real-time image formation of spaceborne synthetic aperture radar (SAR).

Description

technical field [0001] The invention belongs to the technical field of digital signal processing, relates to a Doppler center estimation method, and can be applied to the design of a radar real-time signal processing system, especially in the real-time imaging of a spaceborne synthetic aperture radar (SAR). Background technique [0002] Doppler centroid estimation is an important part of SAR imaging processing, and its role in imaging processing is very important. Inaccurate estimation of the Doppler center will cause the overall offset of the image and affect the positioning of the target in the scene. In severe cases, the frequency band of the scene signal will not match the frequency band of the reference signal, and imaging will not be possible. [0003] Commonly used Doppler centroid estimation methods mainly include energy balance method, correlation function method, and optimal estimation method. Among them, the correlation function method is relatively robust and ca...

AI Technical Summary

Problems solved by technology

In the existing airborne SAR real-time processing system, the estimation of Doppler center usually adopts the digital signal processor DSP as the core processing chip. The advantage of DSP is that the available software resources are abundant, the internal modules are standardized, and the versatility is strong and flexible. Good performance and simple debugging, but the disadvantage is that it works in a fixed mode such as fetching, decoding, and executing, which makes insufficient use of resource efficiency

For the spaceborne SAR system, not only high computing speed is required, but also higher requirements are put forward for the radiation resistance and thermal design of the processor chip due to the limitation of space environment conditions. DSP chips do not have aerospace-grade products, so The method implemented by DSP in the airborne system can no longer meet the requirements of the on-board system, and new devices must be selected to realize the real-time imaging processing of the on-board SAR

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