The Lunar Laser Ranging (LLR) System is a part of the Lunar Exploration. It is used to detect the photons reflected by
the retroreflector on the moon, and to accurately calculate range from the earth to the moon at a certain time, so as to
improve the pointing precision of the telescope and correct the lunar orbit. The data is indispensable for other research
about the moon. This paper not only analyses the main factors (the performance of chosen telescope, the power of laser
used in LLR, the capability of detector) in affecting the detection capability of the Lunar Laser Ranging system, but also
analyses the whole detection capability under the situation of all parts of an apparatus that could be attainable around the
international areas. At last, the economic, feasible, with high performance-to-price ratio supporting programs are presented.
Highly automation is a direction of Satellite Laser Ranging (SLR). The optical path of the laser in the domestic SLR
system often shows instability, which causes errors in the laser orientation and greatly lowers the laser echo rate. In order
to improve the laser echo rate, it's essential to calibrate the laser orientation real-timely. Firstly it's requisite to obtain
precise pointing of laser beam-peak, whose effective way is to locate the position of the beam-peak which is imaged on
the CCD because of the effect of backward scattering. Then the target-missing quantity of the position of the beam-peak
is calculated and transmitted to the servo system of the adjustable mounts for calibrating the laser orientation. Using
Harris corner detecting algorithm, this paper detects the beam-peak of laser, gives the precise point of beam-peak and
lays a foundation for improving the automation of SLR system.
The atmospheric pressure loading coefficient describing the effect of air pressure loading on the site coordinates is one of
the important factors arising in the precise coordinate determination by modern space geodetic techniques such as VLBI,
SLR, GPS and so on. This paper deals with the calculation of the atmospheric pressure loading coefficient of Changchun
SLR station by means of a simple empirical approach using 5 years (2001-2005) observation data, and analysis of the
pressure loading effect on the station height. The 5-year averaging loading coefficient was estimated to be about -0.5
mm/hPa, and the result indicates that, like the other stations, Changchun station coordinates, especially the vertical
component has a close relation with local atmospheric pressure, being very sensitive to atmospheric pressure loading
effect. Also analyzed in this paper is the atmospheric "blue sky" effect on the Changchun SLR station height on the basis
of the loading coefficient estimates.
High frequency, as well as automation and day light ranging, is a signify feature of new generation Satellite Laser
Ranging (SLR) systems. In spite of increase the quantity of observation data, the high frequency SLR can also
significantly improve the SP and NP precision. These trends of SLR technology lead to new requirement of control
circuit. In this paper, an implementation of control circuit in single FPGA chip was present. SOPC (system on
programmable chip) system was proposed to solve these problems. To realize the system, a control circuit custom
component was designed and simulated by us. Then, the component was integrated into a SOPC system. Cooperated
with software, the circuit has the ability to control the SLR system running at high frequency. Finally, the system was
simulated in the Quartus software and NIOS IDE provided by Altera and implemented in an Altera EP1S10 development
kit.
The paper presents the design and development of a medium-size optoelectronic detecting telescope which will be used
for space objects and debris detection. First, the paper introduces the work principle of the detecting system. Then it
gives out the design scheme, the main syetem parameters and the fulfillment of the optoelectronic detecting system. And
last it shows some results of the system to track the space objects.
Precision (rms) or accuracy of Satellite Laser Ranging (SLR) system is the most important value. Now centimeter or
millimeter level is the international standard of SLR system. The performance of start detector in the system can
contribute to or decide the whole system range precision and accuracy. This part is one of the most important parts for
system performance. Certainly, laser pulse width and receiving detector rising time, and constant fraction discriminator
(CFD), other electronics can also contribute to the system performance. So choosing a suitable start detector can make
system to produce the best results, best performance and to show a great important and high percentage for application.
This paper introduces the performance test of several optoelectronic detectors as start detector in SLR system, such as
DET210, SV2-FC, Ultrafast-2 and GT106 etc. After showing the photodetectors specific parameters, the performance
test results as start detector to range ground target and satellites are presented, and last the results are analyzed and
compared.
Galileo system consists of 27 satellites distributed in three uniformly separated planes. At the end of 2005, one satellite,
Galileo In-Orbit Validation Element-A (GIOVE-A), was launched as planned into an MEO with an altitude of 23,260
kilometers. Carrying a payload of rubidium clocks, signal-generation units, and a phase-array antenna of individual
L-band elements. GIOVE-A started broadcasting on January 28, 2006, securing the frequencies allocated by the ITU for
Galileo. Performance of the on-board atomic clocks, antenna infrastructure, and signal properties is evaluated through
precise orbit determination, supported by Satellite Laser Ranging (SLR), an independent high-precision range
measurement technique for orbit determination based on a global network of stations that measure the round-trip
flight-time of ultra short laser pulses to satellites equipped with laser retro reflector arrays (LRAs). SLR provides
instantaneous range measurements of millimeter-level precision which can be compiled to provide accurate orbits and to
measure the on-board clock error. Given the importance of SLR data for the characterization of the GIOVE-A clocks, the
Changchun SLR station in northeast China was selected among the Chinese stations contributing to the ILRS because it
had demonstrated strong MEO satellite tracking; collocation with an existing International GPS Service station; and good
weather conditions. This paper introduces the SLR system improvement for tracking GIOVE-A satellite in Changchun
station. During the more than two months improvement, the new servo and encoder systems were installed, primary
mirror, second mirror and some other mirrors have been cleaned and recoated, and the laser system was adjusted in order
to improve the laser efficiency and output energy. The paper gives out the improvement results, and the GIOVE-A
satellite observation results.
The daylight tracking observation is necessary and the tendency of Satellite Laser Ranging (SLR) in the future. More
than half of the SLR stations in the world can take the daylight tracking observations. From the experience of the most
successful stations around the world, Changchun station has been working on the daylight tracking technique in recent
years. This paper introduces the performance and progress for SLR system daylight tracking in Changchun station. It
first introduces the problems and difficulties facing this system for daylight tracking - mount model, the separation of
emitting and receiving parts of the telescope, control range gate, and installing narrower filter. Secondly, it presents some
work which has been done in the system for daylight tracking: system stability improvement, laser stability
improvement, mount model adoption, control system, etc. From these analysis and work which has been done, the
system performance has been greatly improved. A routine operation system for daylight tracking observation has been
set up.
This paper introduces some optic-electronic detectors which are applied in Satellite Laser Ranging (SLR) system, such as XP2233B, GDB49, MCP (Micro Channel Plate)-PMT (Photomultiplier Tube), SPAD (Single Photon Avalanche Diode), etc. The comparisons of these detector’s performance and main parameters are given. With the improvement of the parameters, the laser range precision and system stability are improved. The focus is on the widely used detectors -- MCP-PMT and C-SPAD. After comparing the advantage and disadvantage of the two kinds of detectors, the range precision and system stability improvement are presented based on the detectors.
In this paper, the microwave radiometer with computer controlled automatic gain compensation is briefly introduced. By using this method, a four-frequency-band (1.4GHz, 3.0GHz, 5.4GHz, 10.0GHz) compact microwave radiometer machine is designed and developed. After showing the methods of selecting some parameters of the system, the paper gives out the system calibration equation, sensitivity and linear correlative coefficients. Finally, it presents the system test results of the long-term stability, the ability of gain compensation, and also the test results of some crops: wheat, corn, and bean.
This paper presents the test results of
a clock distributor, which was applied
to Changchun and Beijing Satellite Laser
Ranging (SLR) system. It gives out the
ground target calibration results and
ranging satellite results. After
applying the clock distributor, the
precision of calibrating ground targets
and ranging satellites has several mm
improvements. It also shows the
comparison results of standard frequency
source provided only by HP58503A GPS
receiver and by HP58503A GPS receiver
through the clock distributor.
Satellite Laser Ranging (SLR) is a very important technical means in geodesy and geodynamics. It is also a very important tool to calibrate the spaceborne altimeter, such as Geos-3, Seasat, Geosat, ERS 1 and 2, TOPEX/Poseidon, and just launched GFO-1, and it is the only way to calibrate the spaceborne altimeter satellite on-orbit. So the precision and accuracy of SLR system will play an important role in determining the measurement accuracy of the altimeter. This paper presents the improvement of range precision and stability laser ranging system in Changchun Artificial Satellite Observatory, the range precision and stability of the satellite laser ranging system have been greatly improved. A high quantum efficiency, low time walk, compensated, low work voltage and fast response time single photon avalanche diode was applied to the system, besides a portable calibration system and three new near ground targets. Now, the system produces subcentimeter single-shot precision and precision for mm level for normal point data. The long term system stability is improved from 4 cm to better than 2 cm, the range bias is less than 6 cm, and the time bias is less than 50 μs.
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