There are five channels in the Very High Resolution Scanning Radiometer (VHRSR) installed on FY-1 Meteorological satellite, the channel 1 to 4 are visible and near infrared wavebands. The channel 1, 0. 58-0. 68,2 m, is used for detecting cloud cover, vegetation and content of the mud and the sand in the sea, the channel 2, 0. 725-1. 1 g m, for identifying boundary of water and land, the channels 3 and 4, 0. 48-0. 53 m and 0. 53-0. 58 p. m respectively, for detecting the content of chlorophyll in the sea. In order to obtain the target features of the earth from the output signal of VHRSR, radiation calibration of each channel of VHRSR should be finished before launching the satellite. The main task of radiation calibration is to determine the gain and dynamic range of amplifier of each channel to assure that the useful signal of the target is neither saturated nor too small. By means of radiation calibration of visible and near infrared wavebands, the relative curve between output signal from VHRSR and radiation brightness or albedo of the earth target is also determined so that when satellite operates, radiation brightness or albedo of the earth target can be obtained by means of output signal of VHRSR.
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