Detection and Correction of Crosstalk Within Channels of Long-Linear-Array Detectors

The payload Geostationary High-speed Imager (GHI) onboard the Fengyun-4B satellite employs the technology of the long-linear-array detectors. The longwave infrared channel of GHI exhibits significant nonuniformity, manifested as brightness temperature discontinuities at the edges of adjacent swaths and abnormal signal value drops at the edges of the full-disk targets. To address this issue, ground tests were conducted on the GHI backup unit, identifying channel crosstalk within the infrared bands, which further impacted the radiometric calibration coefficients. Based on these ground tests, a linear crosstalk model was established along with a solution method. Subsequently, a crosstalk parameter solving algorithm suitable for long-linear-array detectors was proposed. This algorithm can solve the crosstalk coefficients using data from the edge regions of the full disk in orbit and use them for correction. After applying this algorithm, the crosstalk phenomenon was well corrected, reducing nonuniformity by more than 90%. Furthermore, a fixed-scene processing method based on the generalized inverse matrix of least squares was proposed, enabling automated operation of the crosstalk correction algorithm. Currently, this algorithm has been deployed in the Data Acquisition and Tele-command System (DTS) of the Fengyun satellite, where it is used for real-time correction of GHIs’ data.