Spaceborne Moderate Resolution Spectrometer
3. Preliminary experiment results.
Using an integrating sphere and radiation black body, some measurements have been made to validate the design. The results show signal-to-noise ratios of 700 that are better than requirements. From the screen of a ground detecting equipment designed specially for checking the sensor, clear target images were seen. To ensure the quality of raw spectral images of the sensor, the inherent non-uniformity of the FPA must be corrected in real time. Because the double-side reflective scanning mirror is used, the non-uniformity of reflectance of double sides should also be corrected. The method of correction for non-uniformity in real time has been developed. A ROM device is used to save the correcting table. The input of the ROM address lines consists of the output of the 12 bit A/D, the flag bit of a side of the double-sides scanning mirror, and the timing logic address of each detector readout circuit of the FPA. The output of the ROM is the 12 bit data that has been corrected. The results of measurements indicate that the non-uniformity of raw spectral image output by the Moderate Resolution Imaging Spectrometer is about 1% in laboratory using the integrating sphere radiation source.
Airborne test flights had been carried out in summer this year to check the Moderate Resolution Imaging Spectrometer design and applications. The 45 G byte data, obtained from 4 flights totaling 12 hours and recorded by an EXABYTE 8900 tape in the rate of 7.2 Mbps, have shown that the performance of the Moderate Resolution Imaging Spectrometer meet the requirements and that high image quality has been achieved. The preliminary applications show that these data are useful.
Table 1. Specifications of the Space-borne Moderate Resolution Imaging Spectrometer
| Channel |
VIS and NIR |
SWIR |
Thermal IR |
|
| Spectral range um |
0.403~0.803
0.843~1.043 |
2.15~2.25 |
8.4~8.9 |
10.3~11.3
11.5~12.5 |
| Channels |
30 |
1 |
1 |
2 |
| Spectral resolution |
20nm |
20nm |
0.1um |
0.5um |
| S/N |
>250 |
>200 |
<0.4K |
<0.3K |
| Measurement Accuracy |
10% (had better 5%) |
|
1K (at 300K) |
1K (at 300K) |
| Ground resolution |
500 meters |
| Scanning VOF |
89 degree |
| Plarization |
About 5% |
| Digitization |
12 bit |
| Alignment accuracy |
0,5 pixel |
| Spectral calibration accuracy |
1nm (Special)5nm (general) |
|
| Data rate |
7.2 Mbps |
