2 MCSR

1. The specifications of MCSR are listed in the following tables.

Table 1 Main System Specification

Spin rate	100 rpm
Image size	20° x20°
Image rate	30 min
Scan step distance	0.14 mr
Aperture	400 mm
Lifetime	3 years
Weight	75 Kg
Size	1.3 x 0.8 x 0.6m

Table 2 Technical requirements of the instrument

Parameter	Vis-channel	IR-channel	WV-channel
Number of chan.	4(+4back-up)	1(+1back-up)	1(+1back-up)
Wave band	0.5~1.05mm	10.5~12.5mm	6.3~7.6mm
IFOV	0.04 mr	0.16mr	0.16mr
Number of line/pic.	10000	2500	2500
Detector	S photodiode	HgCdTe	HgCdTe
Band width of circuit	130.8 KHz	32.7KHz	32.7KHz
Dynamic range	0.5~95% (albedo a)	180~320K	200~300K
S/N or NEDT	³43(a =95%) ³1.5(a =95%)	£0.5(300K)	£1K(260K)
Calibration on- Board satellite	The sun, cold space, electronic	Balckbody, cold space, electronic	Blackbody, cold space electronic
Sampling rate	437.5K samp./s	109.4K samp./s	109.4Ksamp./s
Quantized level	6 bit	8bit	8 bit
Transmission rate	14 Mbps	14 Mbps	14 Mbps

2. Operation principle of MCSR When the satellite rotates at the rate of 100rpm, the MSCR accomplishes the scan of the earth from west to east. When the field of view of the MCSR scans out of the edge of the earth, the telescope on the MCSR starts to step at a step angle of 0.14 mr. Thus, the MCSR conducts stepping of the earth 2500 steps from north to south step by step, obtaining 10000 visible scan lines, 2500 lines for IR and water vapor respectively. Normally, it takes 25 minutes to accomplish a full-frame scan and takes 2.5 minutes for the telescope to scan back, then, 2.5 minutes for the satellite to get stabilized, so, it takes altogether 30 minutes to accomplish one frame of an image. The MCSR can also conduct, according to remote controlled command, regional scan and single line scan, adjusting for channel gain, adjustment of focal plane of visible, IR and water vapor channels.
3. Composition of MCSR
   It mainly consists of
   1. Optical system: Primary optical system, rear optical system and calibration optical system.
   2. Mechanical structure: main structure, scanning mechanism, telescope, focusing mechanism and calibration mechanism .
   3. Electronics : information processing for visible, IR and water vapor channels, video digital multiplexer (VDM), controller, telemetry and power.
   4. Radiant cooler
   5. Detector PIN Si photodiode for visible channel, HgCdTe detectors for IR and water Vapor channels.