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Remote control and satellite tracking subsystem The tracking system works in micro-step regime with a computer step of correction = 0.003 arcsec per second of time and a maximum speed of correction up to 4.6 arcsec per second of time. The step regulation is possible directly from block of correction situated near the telescope. Also it is possible to correct the moving of the telescope using the computer RS-485 interface in remote mode. The pointing on the satellite is performed by CMOS camera (2000x3000 pix) with wide field of view. Another cooled small CCD camera (582x752 pix) with narrow field of view is used for tracking purposes. | |||
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Receiving subsystem (avalanche photodiode (APD)
The APD module was constructed for performing experiments of receiving of 2 Mbps signals from “ARTEMIS”
using the Cassegrain focus of 0.7m telescope. The Si avalanche photodiode with sensitivity peak at
800 nm is thermoelectrically cooled with possibility of temperature stabilization of APD in range 4 – 25 C.
The DC-DC converter with filter is used as voltage source for APD. The APD, 1 stage thermal cooler,
thermal sensor and low noise current-to-voltage preamplifier circuit are mounted in compact hermetic box (picture).
The noise level is 0.15 nW in frequency band 8 MHz. A spectral response range is 400 – 1000 nm.
The oscillography of square inpute optical pulses with width 250 ns is on the picture.
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Receiving optical module with frequency band 350 MHz. GaAs PIN photo diode. Optical band is 790-1050 nm
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The oscillography of square input laser pulses with width 10 ns and period 50 MHz. Rise/down times are 2.5 ns
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Laser transmitting subsystem
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Electronic module for thermoelectric cooling of laser diode
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Electronic module for turbulence compensation system
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Multi-element (6 elements) quadrant photodetector module for turbulence compensation system
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Front view of multi-element quadrant photodetector module for turbulence compensation system
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The module of precision current 0-350 mA for test of laser diodes
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Laser module with thermoelectric stabilisation of laser diode.
Termostabilisation from - 5 deg. C up to +10 deg. C. Tunable wavelength.