A Novel Channel Inconsistency Estimation Method for Azimuth Multichannel SAR Based on Maximum Normalized Image Sharpness

Performance Analysis of Channel Imbalance Control and Azimuth Ambiguity Suppression in Azimuth Dual Receiving Antenna Mode of LT-1 Spaceborne SAR System

“…The experimental results in Sections 3 and 4 demonstrate an effective suppression of azimuth ambiguities for different scene targets with the LT-1 DRA mode. The simulation experiment in Section 3 shows that, compared with other SAR systems with shorter wavelength segments, LT-1 adopts an L-band, which can significantly reduce the influence of To quantitatively analyze the image quality, the ghost-real target energy ratio (GTER) [20] is employed to measure the suppression of the ghost target in the final focused image without phase error calibration, which is defined as GTER = 20 log 10 max(|I G |) max(|I R |) (30) where max(|I G |) denotes the maximum amplitude value of pixels of ghost targets, and max(|I R |) denotes the maximum value of pixels of real targets. The GTER result of Target 1 is −52 dB, which shows the LT-1 s sound azimuth ambiguity performance.…”

“…To quantitatively analyze the image quality, the ghost-real target energy ratio (GTER) [20] is employed to measure the suppression of the ghost target in the final focused image without phase error calibration, which is defined as The displacement in azimuth and slant range of the first-order ambiguity relative to the primary response is approximately given by [34,35] ∆ az,1 ≈ λPRFR 0 2V s (28)…”

“…Although AMC SAR has many advantages, using multiple channels to receive echo signals also brings a variety of error sources, including phase synchronization error, baseline error, channel error, and attitude error [19][20][21]. These errors lead to inconsistent amplitude and phase characteristics of each channel's echo, seriously restricting the performance of the AMC SAR system.…”

“…At the same time, the estimation accuracy of the self-correction method has been dramatically improved through constant updating and iteration. Currently, the commonly used self-calibration methods include the signal subspace method (SSP) [23], azimuth time domain cross-correlation method (ATC) [24], minimum variance distortionless response method (MVDR) [25], the image weighted minimum entropy method (WME) [26,27], the image least L1-norm method (LLN) [19], maximum normalized image sharpness method (MNIS) [20], and the minimizing the sum of the sub-band norm method (MSSBN) [28]. Considering the estimation accuracy and computational efficiency, this paper proposes a phase error estimation method that maximizes the L1 norm of the sum (MLNS) of multichannel 2-Dimension (2D) frequency domain echo signals based on the MSSBN method.…”