Precise Delay Calibration of Wideband Digital Array Based on FPGA

The wideband digital array radar has a considerable advantage for its high-resolution. However, the inconsistency of the time delay in each channel leads to degradation of the beamforming performance. The traditional solutions have several disadvantages, such as precision deficiency and hardware cost. In this paper, we proposed a precise delay calibration method for wideband digital arrays. The time-frequency characteristic of LFM signal is exploited to equivalently achieve the delay calibration by frequency compensation. Parameterized iterative CZT is used to realize the high-precision frequency measurement by Cordic. Then the corresponding frequency compensation can be embedded into the existing digital down-conversion module without adding extra hardware. Finally, simulation and measured results are performed to confirm the superiority of the proposal.