Atmosphere temperature profile sounder, ATPS-II
Infrared detectors, photo-filters and radiative cooler
LW has twelve photo channels (6.7-15mm). The detector is made by Gh Cd Te with area of 2.1*2,5mm
2, D
*p is 5 X 10
9 cm. Hz
½. W-1. The biased power is less than 15mw and working temperature is 105k.
SL has seven photo channels (3-5
mm). The detector is made by InSb that D
*P is superior to 5 X 10
10 cm. Hz
½. w-1 and working temperature is 105k also.
The visible spectrum detector is a silicium with fiel cone. Its sensational responsibility is 0.3 A/w and dark current is less than 3.X10-10 a with area of 3mm (diameter).
The narrow and super narrow interference photo-fiele (NIF) are key components in ATPS-II. Under the success study of nine narrow photo-filter in ATPS-I, Shanghai Institute of Technical Physics has manufactured twenty super narrow photo-filters to ATPS-II. TABLE 2 gives parameters of twenty super narrow photo-filters.
The radiative cooler in ATPS-II adhered to optical mechanism so that the structure is compact and improved the optical effectivenesss. The radiative cooler is experimented in cooler background of liquid nitrogen (80k) and liquid helium (29k). The second stage radiative cooler temperature is 111.3k and 98.6k.
Electronic System
Electronic system is composed fo Analog circuits of LW,SW and visible spectrum Multiswitch, A/D converter, Microprocessor I, Microprocessor II, Driver circuits of scanning step motor, chopper motor and filter wheel, temperature measurement and control circuits power of DC converter and so on.
Analog circuits are made from preamplifiers, clamp circuits, electronic filters. Phase amplifiers and integrators.
It is important to solve problems of the error from the interactive effect of electronic signals in different optical channels and the ratio of gignal-noise in analog circuits. According to experiments and theoretical calculates, the band with of analog circuits are 670 Hz to 1250 Hz (LW circuit), 420 Hz to 1500 Hz (SW circuit) and 170 Hz to 1750 Hz (visible).
Functions of Microprocessor I in ATPS -II are:
- Data acquisition from 13 bites A/D converter then preprocessing it
- Connected with F-Y Information processor (FIP)
- Two pattern control of step scanning motor (fly pattern and calibration patttern)
- The transitional processing control of step scanning motor in steps
The transitional processing control of step scanning motor is a key technique, which influence properties of ATPS-II. The transitional process of High Resolution Radiation Sounder (HIRS/2) in TIROS-N and NOAA satellites series (US) is controlled by use of close loop control of step motor, velocity motor and torque motor only have 35 ms in the transitional process. In ATPS-II. We use electronic control technique to control transition process of step scanning motor and the transitional time is less than 15ms. Compare to HIRS/2, two LW channels and one SW channel are added and extend the ability of TPS-II.
Microprocessor II consists of following functions:
- Output diffent control signals that analog circuits, Multiswitch and A/D converter
- Send out standad signals for electronic calibration.
- control photo-filter wheel and chopper for synchromotion
Conclusion
There is a great breakthrough in IR detectrs, narro photof;iters, radiative cooler an transitional process control of scanning step. The optical, mechanical and electronic properties satisfied the requirement of design of ATPS-II . Because of the great impovement of opticalmechanism in ATPS-II, it extend the ability of LW, SW and visible channels and develop the functions of F-Y Meterological Satellites.
References
- E.W.K oening, NASA-CR-144743, 1975, 28670
- Arthur Schwalb, the TIROS-N/NOAA A-G Satellite Series, NESS 95, Wasthington D.C. Mar. 1978
- Wang Mochang, Atmosphere Temperature Profile Sounder, ATPS-1, Chinese J. In frared Res. 6(1987) 17-23.
