CN104535992B - Satellite laser ranging system - Google Patents
Satellite laser ranging system Download PDFInfo
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- CN104535992B CN104535992B CN201410781776.1A CN201410781776A CN104535992B CN 104535992 B CN104535992 B CN 104535992B CN 201410781776 A CN201410781776 A CN 201410781776A CN 104535992 B CN104535992 B CN 104535992B
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- laser
- satellite
- moment
- telescope
- ranging
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/06—Systems determining position data of a target
- G01S17/08—Systems determining position data of a target for measuring distance only
- G01S17/10—Systems determining position data of a target for measuring distance only using transmission of interrupted, pulse-modulated waves
- G01S17/18—Systems determining position data of a target for measuring distance only using transmission of interrupted, pulse-modulated waves wherein range gates are used
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- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Optical Radar Systems And Details Thereof (AREA)
Abstract
The invention provides a kind of satellite laser ranging system, the satellite laser ranging system, it is characterised in that it includes ranging control computer, laser, transmitter-telescope, receiving telescope, data acquisition computer, event timer, range gate circuit board, artificial satellite track sight and single-photon avalanche diode.Satellite laser ranging system provided by the invention, main ripple moment and echo moment are recorded by event timer, the application of High Resolution range gate can greatly improve the signal to noise ratio of system, and then effective echo data amount is improved, while considerably improve the range accuracy and range capability of system.
Description
Technical field
The present invention relates to laser ranging field, more particularly to a kind of satellite laser ranging system.
Background technology
Satellite laser ranging (SLR) technology is measuring laser pulse by observation station, (to lead to via cooperative target
Often it is equipped with the satellite of retroeflector) reflection, based on the flight time for finally returning back to observation station, single measurement precision
Up to Centimeter Level or even the satellite ranging means of inferior centimeter order.
In existing satellite laser range-measurement system, laser pulse caused by laser draws through tortuous light path and Cude light paths
Enter transmitter-telescope, transmitter-telescope carries directive after laser beam datum the artificial satellite of backward corner reflector, while is sending out
Penetrate and very small part taken out in light path, electric pulse is formed by main ripple sample circuit, is divided into two-way, all the way referred to as main wave impulse,
After pulsqe distributor shaping, as enabling signal or commencing signal, for start time-interval counter (such as HP5370B,
SR620), it is recording laser emission time service that another way, which is clocked into circuit, the laser pulse of directive artificial satellite, through artificial
Ground is returned to after the reflector reflection of satellite, is received by receiving telescope system, through light in the focus of receiving telescope system
Power conversion device single-photon avalanche diode (C-SPAD) is converted to electric pulse, then echo arteries and veins is formed after pulsqe distributor shaping
Punching, as door signal or stop signal, for the counting of dwell time interval counter, such time-interval counter is just remembered
The time interval between main wave impulse and echo impulse, i.e. shuttle flight of the laser between observation station and artificial satellite have been descended in record
Time t, distance measurement value can be calculated by being multiplied by light velocity c.
However, above-mentioned traditional SLR technologies that the flight time of single laser pulse is measured using time-interval counter,
For the satellite of multiple orbital attitudes, flight time of laser pulse is from several milliseconds to hundreds of milliseconds, therefore the time
Interval clocking technique limits the working frequencies of SLR systems, for high rail satellite, laser repetition rate can only in below 10Hz,
Because laser repetition rate is low, it is low to cause system signal noise ratio so that system is low in high rail satellite and ground shadow in the measurements
Inferior capabilities during rail satellite.
The content of the invention
(1) technical problems to be solved
The technical problem to be solved in the present invention is to provide a kind of satellite laser ranging system, it is possible to increase the letter of system
Make an uproar ratio.
(2) technical scheme
To be controlled in order to solve the above technical problems, the invention provides a kind of satellite laser ranging system, including ranging
Computer, laser, transmitter-telescope, receiving telescope, data acquisition computer, event timer, range gate circuit board, people
Make satellite track sight and single-photon avalanche diode；
The ranging control computer calculate in real time forecast position of the artificial satellite under survey station coordinate system and according to
The forecast position obtains guidance information, and periodically calculates laser ignition moment and range gate forecast moment；
The artificial satellite track sight is connected with the ranging control computer, transmitter-telescope, receiving telescope, institute
State artificial satellite track sight the transmitter-telescope controlled according to the guidance information and receiving telescope follow it is described artificial
Satellite rotates；
The range gate circuit board is connected with the ranging control computer, laser, single-photon avalanche diode, described
Range gate circuit board controls the igniting of the laser according to the laser ignition moment, and is given the correct time in advance according to the range gate
Carve and control the enabled of the single-photon avalanche diode；
The laser is connected with the transmitter-telescope, passes through the transmitting in laser pulse caused by the laser
Described in telescope directive while artificial satellite, fraction of laser light is taken from the transmitting light path of the laser pulse and forms main ripple arteries and veins
Punching；
The single-photon avalanche diode is connected with the receiving telescope, and the single-photon avalanche diode connects described
The reflection laser for receiving the artificial satellite that telescope receives is converted to electric pulse, and echo arteries and veins is formed after the electric pulse shaping
Punching；
As the main ripple moment at the time of event timer records the main wave impulse, record the echo impulse when
Quarter is used as the echo moment；
The data acquisition computer is connected with the event timer, and the data acquisition computer is according to the event
Main the ripple moment and echo moment of timer record carry out ranging.
Further, the range gate circuit board includes latch, the first buffer, local clock, comparator and second
Buffer；
The latch is connected with first buffer, the local clock；
The comparator is connected with the local clock, the second buffer；
First buffer, second buffer are connected with the ranging control computer.
Further, first buffer, second buffer pass through parallel port and the ranging control computer phase
Even.
Further, in addition to Time And Frequency benchmark provides device, for for the satellite laser ranging system
Time reference and frequency reference are provided, the Time And Frequency benchmark, which provides device, includes GPS Timing Receivers, pulsqe distributor
And frequency divider, the pulsqe distributor are connected with the GPS Timing Receivers, the frequency divider is awarded with the GPS
When receiver be connected.
Further, the repetition rate of the laser transmitting laser is 2KHz.
(3) beneficial effect
Satellite laser ranging system provided by the invention, when recording main ripple moment and echo by event timer
Carve, the application of High Resolution range gate can greatly improve the signal to noise ratio of system, and then improve effective echo data
Amount, while considerably improve the range accuracy and range capability of system.
Brief description of the drawings
Fig. 1 is a kind of schematic diagram for satellite laser ranging system that embodiment of the present invention provides；
Fig. 2 is the schematic diagram for another satellite laser ranging system that embodiment of the present invention provides；
Fig. 3 is a kind of schematic diagram for artificial satellite track sight that embodiment of the present invention provides；
Fig. 4 is a kind of schematic diagram for range gate circuit board that embodiment of the present invention provides.
Embodiment
With reference to the accompanying drawings and examples, the embodiment of the present invention is described in further detail.Implement below
Example is used to illustrate the present invention, but is not limited to the scope of the present invention.
Fig. 1 is a kind of schematic diagram for satellite laser ranging system that embodiment of the present invention provides, including ranging control
Computer 1 processed, laser 2, transmitter-telescope 3, receiving telescope 4, data acquisition computer 5, event timer 6, range gate
Circuit board 7, artificial satellite track sight 8 and single-photon avalanche diode 9；
The ranging control computer calculate in real time forecast position of the artificial satellite under survey station coordinate system and according to
The forecast position obtains guidance information, and periodically calculates laser ignition moment and range gate forecast moment；
The artificial satellite track sight is connected with the ranging control computer, transmitter-telescope, receiving telescope, institute
State artificial satellite track sight the transmitter-telescope controlled according to the guidance information and receiving telescope follow it is described artificial
Satellite rotates；
The range gate circuit board is connected with the ranging control computer, laser, single-photon avalanche diode, described
Range gate circuit board controls the igniting of the laser according to the laser ignition moment, and is given the correct time in advance according to the range gate
Carve and control the enabled of the single-photon avalanche diode；
The laser is connected with the transmitter-telescope, passes through the transmitting in laser pulse caused by the laser
Described in telescope directive while artificial satellite, fraction of laser light is taken from the transmitting light path of the laser pulse and forms main ripple arteries and veins
Punching；
The single-photon avalanche diode is connected with the receiving telescope, and the single-photon avalanche diode connects described
The reflection laser for receiving the artificial satellite that telescope receives is converted to electric pulse, and echo arteries and veins is formed after the electric pulse shaping
Punching；
As the main ripple moment at the time of event timer records the main wave impulse, record the echo impulse when
Quarter is used as the echo moment；
The data acquisition computer is connected with the event timer, and the data acquisition computer is according to the event
Main the ripple moment and echo moment of timer record carry out ranging.
Wherein, the repetition rate of the laser transmitting laser is 2KHz.
Embodiment of the present invention provide satellite laser ranging system, by event timer record the main ripple moment and
At the echo moment, the signal to noise ratio of system can be greatly improved, and then improve effective echo data amount, while considerably improved and be
The range accuracy and range capability of system.
Fig. 2 is the schematic diagram for another satellite laser ranging system that embodiment of the present invention provides, and this is artificial to defend
Star LDMS includes ranging control computer, artificial satellite track sight, data acquisition computer, laser, event
Timer, range gate circuit board, emission system, reception system and single-photon avalanche diode (C-SPAD), in addition to the time with
Frequency reference provides device；
Wherein, artificial satellite track sight may include servo module and time module, as shown in figure 3, wherein servo module
Including direct current torque motor, Renishaw Circular gratings, tachometer generator, direct current servo driver, encoder to count card and D/A
Card；Time module may include GPS Timing Receivers (such as HP58503), antenna, counter card (such as TMC-10), in laser satellite
In range-measurement system, satellite is calculated in the general Satellite Orbit Prediction parameter provided using international laser ranging service network (ILRS)
D coordinates value (azimuth, the angle of pitch, time) under survey station coordinate system, by making the time module be kept with UTC time
It is synchronous, so as to ensure that telescope is accurately directed to the satellite that passes by.Wherein, above-mentioned D/A cards, encoder to count device card, meter
Number device Ka Kenei is embedded in ranging control computer.
Specifically, ranging control computer be mainly responsible for calculating in real time forecast position of the satellite under survey station coordinate system and
Guidance information is issued to servo module, and periodically calculates range gate forecast moment and laser ignition moment and to range gate
Circuit board issues；
Servo module receive from ranging control computer guidance information control emission system in transmitter-telescope and
Receiving telescope in reception system follows satellite to rotate；
The Time And Frequency benchmark provides device and is used to provide time reference and frequency for artificial satellite laser range-measurement system
Benchmark, GPS Timing Receivers, pulsqe distributor and frequency divider are specifically included, wherein, pulsqe distributor connects with GPS time services
Receipts machine is connected, and frequency divider is connected with GPS Timing Receivers.；
Information accurately controls igniting and the C- of laser at the time of range gate circuit board is according to from ranging control computer
SAPD's is enabled；
Data acquisition computer periodically reads in main ripple moment sequence and echo moment sequence, foundation from event timer
Satellite alert is accurately matched to main ripple moment and echo moment, so as to which laser time of flight be calculated.Specifically, swashing
While laser pulse caused by light device is by transmitter-telescope directive artificial satellite, by photoelectric probe, constant proportion time discriminator from
Fraction of laser light is taken in the transmitting light path of laser pulse and forms main wave impulse；When receiving telescope receives the reflection of artificial satellite
During laser, the reflection laser is converted to by electric pulse by single-photon avalanche diode, then by interface card by the electricity
Shaping pulse is so as to forming echo impulse；In above process, when at the time of event timer recording main wave impulse as main ripple
Carve, as the echo moment at the time of recording echo impulse, then data acquisition computer is according to the master recorded in event timer
Ripple moment and echo moment carry out ranging.
As shown in figure 4, above-mentioned range gate circuit board includes latch, the first buffer, local clock, comparator and the
Two buffers；Wherein, the latch is connected with first buffer, the local clock；The comparator with described
Ground clock, the second buffer are connected；First buffer, second buffer are connected with the ranging control computer.
Specifically, Xilinx Spartan3 Series FPGAs can be used (Field Programmable Gate Array, to show
Field programmable gate array) core devices of the device as the range gate circuit board.Mainly three are realized inside the range gate circuit board
Big function, it is that foundation, the gate moment of local clock compare output, main ripple epoch latches output respectively.Specifically, local clock
It is 5ns to establish resolution ratio by the 1PPS signals and 10MHz signals that receive, and 30us sheet is less than with UTC time synchronization accuracy
Ground clock value；When there is main ripple signal to reach, then clock value now is latched and be sent into caching, sent periodically by parallel port
To computer；Periodically receive the range gate forecast moment and laser ignition moment issued from computer, by these moment and
Present clock is compared, if equal output pulse signal to C-SPAD or laser, wherein, first buffer,
Second buffer can be connected by parallel port with the ranging control computer, so as to realize range gate circuit board and ranging control
Data transfer between computer processed.
The present invention by the laser of higher laser repetition rate and its technology by introducing SLR fields, using event timing
Device records main ripple moment and echo moment, and is matched according to Satellite Orbit Prediction, and then obtains laser time of flight, can
Substantially increase packing density and the detection probability of success, the low orbit satellite in detection in high rail satellite and ground shadow in the unit interval
When relative to traditional SLR Technological expressions go out great advantage.
Embodiment of above is merely to illustrate the present invention, and not limitation of the present invention, about the common of technical field
Technical staff, without departing from the spirit and scope of the present invention, it can also make a variety of changes and modification, thus it is all
Equivalent technical scheme falls within scope of the invention, and scope of patent protection of the invention should be defined by the claims.
Claims (4)
1. a kind of satellite laser ranging system, it is characterised in that looked in the distance including ranging control computer, laser, transmitting
Mirror, receiving telescope, data acquisition computer, event timer, range gate circuit board, artificial satellite track sight and monochromatic light
Sub- avalanche diode；
The ranging control computer calculates forecast position of the artificial satellite under survey station coordinate system and according to described in real time
Forecast position obtains guidance information, and periodically calculates laser ignition moment and range gate forecast moment；
The artificial satellite track sight is connected with the ranging control computer, transmitter-telescope, receiving telescope, the people
Make satellite track sight controls the transmitter-telescope and receiving telescope to follow the artificial satellite according to the guidance information
Rotate；
The artificial satellite track sight includes servo module, and servo module receives the guidance information from ranging control computer
The receiving telescope in transmitter-telescope and reception system in control emission system follows satellite to rotate；
The range gate circuit board is connected with the ranging control computer, laser, single-photon avalanche diode, the distance
Gate circuit plate controls the igniting of the laser according to the laser ignition moment, and forecasts moment control according to the range gate
Make the enabled of the single-photon avalanche diode；
The laser is connected with the transmitter-telescope, is looked in the distance in laser pulse caused by the laser by the transmitting
While mirror is to the artificial satellite, fraction of laser light is taken from the transmitting light path of the laser pulse and forms main wave impulse；
The single-photon avalanche diode is connected with the receiving telescope, and the single-photon avalanche diode hopes described receive
The reflection laser for the artificial satellite that remote mirror receives is converted to electric pulse, and echo impulse is formed after the electric pulse shaping；
As the main ripple moment at the time of event timer records the main wave impulse, make at the time of recording the echo impulse
For the echo moment；
The data acquisition computer is connected with the event timer, and the data acquisition computer is according to the event timing
Main the ripple moment and echo moment of device record carry out ranging；
The range gate circuit board includes latch, the first buffer, local clock, comparator and the second buffer；
The latch is connected with first buffer, the local clock；
The comparator is connected with the local clock, the second buffer；
First buffer, second buffer are connected with the ranging control computer.
2. satellite laser ranging system according to claim 1, it is characterised in that first buffer, described
Second buffer is connected by parallel port with the ranging control computer.
3. satellite laser ranging system according to claim 1, it is characterised in that also including Time And Frequency benchmark
Device is provided, for providing time reference and frequency reference, the Time And Frequency for the satellite laser ranging system
Benchmark, which provides device, includes GPS Timing Receivers, pulsqe distributor and frequency divider, the pulsqe distributor and the GPS
Timing Receiver is connected, and the frequency divider is connected with the GPS Timing Receivers.
4. satellite laser ranging system according to claim 1, it is characterised in that the laser transmitting laser
Repetition rate is 2KHz.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410781776.1A CN104535992B (en) | 2014-12-16 | 2014-12-16 | Satellite laser ranging system |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410781776.1A CN104535992B (en) | 2014-12-16 | 2014-12-16 | Satellite laser ranging system |
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| CN104535992A CN104535992A (en) | 2015-04-22 |
| CN104535992B true CN104535992B (en) | 2017-12-01 |
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| CN201410781776.1A Expired - Fee Related CN104535992B (en) | 2014-12-16 | 2014-12-16 | Satellite laser ranging system |
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Families Citing this family (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106154246B (en) * | 2015-04-27 | 2018-11-27 | 中国人民解放军63921部队 | Echo photon signal real-time processing method |
| CN106154815A (en) * | 2016-07-27 | 2016-11-23 | 哈尔滨睿之芯信息技术股份有限公司 | Split-second precision TT&C system for the field of finding range |
| CN107015234B (en) * | 2017-05-19 | 2019-08-09 | 中国科学院国家天文台长春人造卫星观测站 | Embedded satellite laser ranging control system |
| CN108519591B (en) * | 2018-04-04 | 2021-11-12 | 中国科学院上海天文台 | Real-time high-precision monitoring device for laser ranging light beam pointing |
| CN109459762B (en) * | 2018-11-20 | 2020-12-15 | 中国测绘科学研究院 | Earth center motion resolving method and device based on GNSS and SLR peripheral solution |
| CN109541627B (en) * | 2018-12-25 | 2024-10-15 | 西南技术物理研究所 | Dual-wavelength self-adaptive range gate laser radar |
| CN110095626B (en) * | 2019-04-04 | 2021-09-14 | 上海集成电路研发中心有限公司 | System with high-speed photoelectric encoder and testing method |
| CN110082772B (en) * | 2019-05-05 | 2024-05-17 | 中国科学院国家天文台长春人造卫星观测站 | Satellite laser ranging system, method and device with real-time controllable signal echo rate |
| CN111505658B (en) * | 2020-04-16 | 2023-04-07 | 中国科学院上海天文台 | Pulse group type laser ranging method with adjustable repetition frequency |
| CN111708034B (en) * | 2020-06-19 | 2023-02-03 | 北京空间飞行器总体设计部 | Dynamic distance threshold setting system of satellite-borne laser ranging system |
| CN111708059B (en) * | 2020-06-24 | 2023-08-08 | 中国科学院国家天文台长春人造卫星观测站 | Laser time transfer processing method, system, storage medium, device and application |
| CN111751835B (en) * | 2020-07-06 | 2023-05-16 | 中国科学院国家天文台长春人造卫星观测站 | Full-waveform satellite laser ranging system and method |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1831559A (en) * | 2006-04-14 | 2006-09-13 | 中国科学院光电技术研究所 | Satellite laser ranging system based on inclination correction |
| CN101915926A (en) * | 2010-08-05 | 2010-12-15 | 中国科学院云南天文台 | Method for confirming one-way distance in satellite laser ranging (SLR) |
| CN204374411U (en) * | 2014-12-16 | 2015-06-03 | 中国测绘科学研究院 | Satellite laser ranging system |
-
2014
- 2014-12-16 CN CN201410781776.1A patent/CN104535992B/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1831559A (en) * | 2006-04-14 | 2006-09-13 | 中国科学院光电技术研究所 | Satellite laser ranging system based on inclination correction |
| CN101915926A (en) * | 2010-08-05 | 2010-12-15 | 中国科学院云南天文台 | Method for confirming one-way distance in satellite laser ranging (SLR) |
| CN204374411U (en) * | 2014-12-16 | 2015-06-03 | 中国测绘科学研究院 | Satellite laser ranging system |
Non-Patent Citations (1)
| Title |
|---|
| 高重复率人卫激光测距的研究;吴志波;《中国优秀硕士学位论文全文数据库 基础科学辑》;20061115;论文第8-12、25、31-32、34、44页 * |
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