... Of particular importance is the multi-spot feature of LOLA that provides instantaneous slopes... more ... Of particular importance is the multi-spot feature of LOLA that provides instantaneous slopes, roughness from the pulse spreading, and albedo from the energy measurement, and enables the orbital cross-over approach to be applied to several measurement types. ...
In addition to the normal two-way satellite laser ranging, the NGSLR system is capable of support... more In addition to the normal two-way satellite laser ranging, the NGSLR system is capable of supporting other types of laser ranging, including one and two-way asynchronous transponder ranging (Degnan, 2002). Currently, the NGSLR prototype is supporting one-way laser ranging to the Lunar Reconnaissance Orbiter (LRO), an uplink only range where NGSLR records the laser fire times, and the spacecraft records the receive events. Analysts form ranges after the pass by correctly associating fires with receive events. Further details on the LRO operations at NGSLR can be found in the manual "Laser Ranging to the Lunar Reconnaissance Orbiter (LRO) from NASA's Next Generation Satellite Laser Ranging Station" (NASA-NGSLR-OPS-LRO), or in various papers and presentations including:
All relevant documentation for the Receiver Algorithms can be found on the ICESat-2 Technical Dat... more All relevant documentation for the Receiver Algorithms can be found on the ICESat-2 Technical Data Management System (TDMS) under the ATLAS Algorithms subsystem. The launch version of the FSW (version 3.1.0) is based upon version 3.7c of this document. The latest version of this document can be found on TDMS under ICESat-2-ALG-PROC-0675. Other related documents, which are currently on the ICESat-2 TDMS, are: The ATLAS Coordinate Systems Descriptions Report, written by Marc Saltzman, is on TDMS under ICESat-2-SYS-RPT-0591. A description of the Simulator is given in the "Guide to the ATLAS Simulator for Users and Programmers" which is on TDMS under ICESat-2-ALG-TN-0577. The document describing the Receiver Algorithms testing is the "ATLAS Receiver Algorithms Test Plan," which explains the tests, including the purpose of each, and how to set each up. This is on TDMS under ICESat-2-ALG-PLAN-0310. The results of the tests described in this document are detailed in the "ATLAS Receiver Algorithms Simulator Test Results" document. This is on TDMS under ICESat-2-ALG-RPT-0659. The latest onboard databases (DEM, DRM, SRM) and their related documentation are on TDMS under ICESat-2-ALG-TN-0362. The latest Receiver Algorithm Parameters are on TDMS under ICESat-2-ALG-SPEC-0255. The Rx Algorithm Parameter Definition Document is on TDMS under ICESat-2-ALG-TN-0876. Changes from v3.2 to v3.3 1-Additional clarification to the NoSig timer state (section 7.4). 2-Change to the calculation of SigLoc in section 5.3 to add 0.5 hwbins or 1 clock cycle. Changes from v3.1 to v3.2 1-In section 5.3 the Algorithms say that if the maximum bin is beyond the last full hardware bin, then the last full software bin should be chosen as the max bin. The Flight Software is not able to do this. We have left the Algorithm as stated, but have written an exception for the FSW. 2-The threshold should be calculated using the threshold function. This has now been explicitly stated in section 5.3. 3-The TEP parameters to be used to define the TEP_NOT region should be converted to start and end and then rounded to the nearest hardware bin boundary. Now stated in section 5.3. 4-Section 5.3 now states that, in the Bnoise calculation, the max bin used should be the one AFTER the TEP_NOT rejections. 5-The calculation of the threshold in section 5.3 has "ceiling" added. 6-In section 7.4 the timer state handling has been clarified, plus other clarifications. 7-The downlink band overlap was clarified in section 7.7. Changes from v3.0 to v3.1 1-In section 7.4 the Telemetry Band Offset usage was clarified for both the NoSig_Timer1 and NoSig_Timer2 cases. Changes from v2.8g to v3.0 1-Due to the leap second being introduced June 30, 2015, GPS-UT1 (aka LS) will become 17 seconds (section 4.3) so this value should now be used as the default. 2-In section 5.4 verbage was added to clarify that the range window being discussed refers to the range window of MF #3 out of the 5 in the Super Frame. 3-In section 7.4 a sentence has been added to clarify which signal location to use if both the primary and tertiary exist. Changes from v2.8d to v2.8g 1-Modified the paragraph related to relief for coastline data (section 7.4). Changes from v2.8d to v2.8f 1-Added some information on the TEP to section 3.10. 2-Corrected the way the PCE delays are being added to the range window (section 4.15). This involves reordering some of the calculations from what was in v2.8d of the document. 3-Changed the conversion of Jrw and Mrw from RWS and RWC in sections 4.16 and 4.17 to use the "ceiling" function instead of "integer" (which is the same as the FORTRAN "floor"). 4-Added note to clip the telemetry band if any part falls outside the range window (section 7.9). 5-Changed the handling of the signal location for the PCE delay in the NoSig_Timer2 case (section 7.4). 6-Changed the handling of the TEP telemetry region for the PCE delay (section 7.5). 7-Updated the Algorithm Parameter files in Appendix F. Changes from v2.8c to v2.8d 1-Cosmetic change to insert a line break between iTEP_flag=0 and next line on page 51. 2-Changed NoSig_Relief1 to NoSig_Scaling in the equation at the top of page 50.
One-way laser ranging technology is applied for the precise orbit determination of LRO, which is ... more One-way laser ranging technology is applied for the precise orbit determination of LRO, which is the first trial for supporting the missions of lunar or planetary spacecraft. In this paper, LRO payload and ground system are discussed for LRO laser ranging, and some errors effecting on time of flight and tracking mount accuracy are analyzed. Additionally several technologies are also analyzed to make laser pulses shot from ground stations to arrive in the LRO earth window. Measurement data of LRO laser ranging verified that these technologies could be implemented for one-way laser ranging of lunar spacecraft.
The SLR2000 Simulator is a software package designed to allow testing of new tracking and ranging... more The SLR2000 Simulator is a software package designed to allow testing of new tracking and ranging algorithms prior to the actual hardware development of NASA’s next generation of Satellite Laser Ranging Systems, called SLR2000. The simulator is written in FORTRAN, currently runs in the HPUX environment, and models relevant errors in the receiver system, tracking mount, weather sensors, station location, system timing, predictions, and others. Recent work includes adding a new signal to noise algorithm, improving the tracking mount model, and developing an acquisition search algorithm. As a consequence of this work, we feel that the simulation results now provide a more realistic example of SLR2000 performance. Simulations of SLR2000 tracking and ranging performance will be presented.
Researchers of NASA's GSFC are currently developing a scanning airborne photon-counting laser alt... more Researchers of NASA's GSFC are currently developing a scanning airborne photon-counting laser altimeter. This paper summarizes the creation of high resolution, precise DEMs from repeat passes of airborne laser scanning surveys to validate this new system. To study coastal erosion several sections of the Atlantic and Pacific coast have been mapped by NASA's Airborne Topographic Mapper (ATM) conical scanning altimeter. We selected two 5 km long and about 1 km wide stretches of the coast in Maryland to create precise Digital Elevation Models. One site is urban area (southern Ocean City) and the other is characterized by coastal marshes and beaches (northern Assateague Island). To obtain a dense data set, we combine laser altimetry data from 21 swaths acquired in 4 different missions. Laser points over planar surfaces, such as flat roofs and parking lots were analyzed to check the the repeatibility of the measurements. The absolute accuracy of the laser scanning was assessed by comparing surfaces extracted from the laser point cloud with GPS and photogrammetry results. These studies confirm the 0.1-0.2 m vertical and submeter horizontal accuracy of the ATM system. At the heart of the interpolation procedure is a bilinear interpolation that determines the surface elevation at the grid posts from planes fitted through the points located within 2 m by 2 m grid cells. Outlier observations are detected by using a robust estimator. The residual of the plane fitting and the uniformity of the distribution of the observations within the grid cells are used to assess the accuracy of the DEM. These parameters suggest an accuracy of 0.3 m or better for 90.4 % of the DEM points on the urban area, and 48.5 % of the points have an accuracy of 0.1 m or better. Similar accuracy is achieved on the site covered by natural vegetation on Assateague Island.
NASA's Space Geodesy Project (SGP) is developing a prototype core site for a next generation ... more NASA's Space Geodesy Project (SGP) is developing a prototype core site for a next generation Space Geodetic Network (SGN). Each of the sites in this planned network co-locate current state-of-the-art stations from all four space geodetic observing systems, GNSS, SLR, VLBI, and DORIS, with the goal of achieving modern requirements for the International Terrestrial Reference Frame (ITRF). In particular, the driving ITRF requirements for this network are 1.0 mm in accuracy and 0.1 mm/yr in stability, a factor of 10-20 beyond current capabilities. Development of the prototype core site, located at NASA's Geophysical and Astronomical Observatory at the Goddard Space Flight Center, started in 2011 and will be completed by the end of 2013. In January 2012, two operational GNSS stations, GODS and GOON, were established at the prototype site within 100 m of each other. Both stations are being proposed for inclusion into the IGS network. In addition, work is underway for the inclusion...
More precise lunar and Martian ranging will enable unprecedented tests of Einstein's theory of Ge... more More precise lunar and Martian ranging will enable unprecedented tests of Einstein's theory of General Relativity and well as lunar and planetary science. NASA is currently planning several missions to return to the Moon, and it is natural to consider if precision laser ranging instruments should be included. New advanced retroreflector arrays at carefully chosen landing sites would have an immediate positive impact on lunar and gravitational studies. Laser transponders are currently being developed that may offer an advantage over passive ranging, and could be adapted for use on Mars and other distant objects. Precision ranging capability can also be combined with optical communications for an extremely versatile instrument. In this paper we discuss the science that can be gained by improved lunar and Martian ranging along with several technologies that can be used for this purpose.
The telescope is designed as a monostatic system to both transmit laser energy and receive light ... more The telescope is designed as a monostatic system to both transmit laser energy and receive light from targeted objects through common optics and a common optical path. The gimbal drives the telescope to track Earth orbiting satellites, stars and fixed ground targets. This subsystem includes the telescope and Coudé path through the tracking subsystem, two cameras mounted on the telescope (one low light camera for viewing dim targets and one wide field of view camera for visual tracking), and all associated environmental monitoring and control devices such as temperature sensors, accelerometers, etc. It also includes the gimbal, encoders, servo electronics, and additional hardware/software to monitor/maintain environmental limits. The gimbal portion of the telescope and gimbal subsystem is attached to a riser which is mounted on a concrete pier and maintains vibrational isolation from other components of the shelter and dome to minimize disturbances to the gimbal pointing and tracking. This subsystem has components in both the dome and the shelter. 4.2. Optical Bench The optical bench (OB) subsystem is designed to allow the laser subsystem, receiver subsystem, and star camera to reside in an environmentally controlled environment, while supporting laser divergence changes for different satellites, point ahead of the laser beam for satellites, beam blocking and beam attenuation for laser safety, system configuration changes for the various modes (star calibration, ground target ranging and satellite tracking), and reduction in the background light that the detector is exposed to (ND wheel, spatial and spectral filters). Laser light is directed along a path on the optical bench that is aligned to the telescope optical axis. The transmitted light goes from the laser to the pit mirror (which is part of the OB subsystem), along the Coudé path, and eventually out through the telescope. Receive light captured by the telescope is directed to the receive path on the optical bench which is also aligned to the telescope optical axis. Finally, this subsystem includes diagnostic components to monitor the laser characteristics and to support alignment. The star camera is part of the optical bench subsystem. The optical bench is contained within the shelter. 4.3. Range Receiver The range receiver subsystem consists of the detector and associated electronics to detect and measure the start and stop event times, support the software s determination of the signal from the background noise and the range to the target, and provide angular offset information to allow for closed loop tracking. The range receiver subsystem also includes the RCE (Range Control Electronics) which provides the software with control of the laser fire frequency, provides the software range gate control for the detector during satellite tracking, and provides fixed ground target range gate control. In addition the range receiver subsystem includes a wide field of view low light Acquisition Camera for use in acquiring targets with poor predictions. Part of this subsystem sits on the optical bench, the rest is in the electronics rack. All are contained within the shelter.
County (UMBC) ScholarWorks@UMBC digital repository on the Maryland Shared Open Access (MD-SOAR) p... more County (UMBC) ScholarWorks@UMBC digital repository on the Maryland Shared Open Access (MD-SOAR) platform. Please provide feedback Please support the ScholarWorks@UMBC repository by emailing [email protected] and telling us what having access to this work means to you and why it's important to you. Thank you.
Lunar Reconnaissance Orbiter (LRO) will be tracked in one-way and two-way modes by microwave and ... more Lunar Reconnaissance Orbiter (LRO) will be tracked in one-way and two-way modes by microwave and optical systems in order to meet its global measurement requirements of 1-m vertical and 50-m horizontal position accuracy. Up to 28 Earth-station laser fires may be received at the antenna-mounted telescope. Earth returns and lunar returns from 5 beams will be time-tagged simultaneously with sub-ns
Laser ranging systems now managed by the NASA Dynamics of the Solid Earth (DOSE) and operated by ... more Laser ranging systems now managed by the NASA Dynamics of the Solid Earth (DOSE) and operated by the Bendix Field Engineering Corporation, the University of Hawaii, and the University of Texas, have produced a wealth of inter-disciplinary scientific data over the last three decades. Despite upgrades to the most of the ranging station subsystems, the control computers remain a mix of 1970s-vintage minicomputers. These encompass a wide range of vendors, operating systems, and languages, making hardware and software support increasingly difficult. Current technology allows replacement of controller computers at a relatively low cost while maintaining excellent processing power and a friendly operating environment. The new controller systems are now being designed using IBM-PC-compatible 80486-based microcomputers, a real-time Unix operating system (LynxOS), and X-windows/Motif graphical user interface. Along with this, a flexible hardware design using CAMAC, GPIB, and serial interfaces has been chosen. This design supports minimizing short and long term costs by relying on proven standards for both hardware and software components. Currently, the project is in the design and prototyping stage with the first systems targeted for production in mid-1993.
... Of particular importance is the multi-spot feature of LOLA that provides instantaneous slopes... more ... Of particular importance is the multi-spot feature of LOLA that provides instantaneous slopes, roughness from the pulse spreading, and albedo from the energy measurement, and enables the orbital cross-over approach to be applied to several measurement types. ...
In addition to the normal two-way satellite laser ranging, the NGSLR system is capable of support... more In addition to the normal two-way satellite laser ranging, the NGSLR system is capable of supporting other types of laser ranging, including one and two-way asynchronous transponder ranging (Degnan, 2002). Currently, the NGSLR prototype is supporting one-way laser ranging to the Lunar Reconnaissance Orbiter (LRO), an uplink only range where NGSLR records the laser fire times, and the spacecraft records the receive events. Analysts form ranges after the pass by correctly associating fires with receive events. Further details on the LRO operations at NGSLR can be found in the manual "Laser Ranging to the Lunar Reconnaissance Orbiter (LRO) from NASA's Next Generation Satellite Laser Ranging Station" (NASA-NGSLR-OPS-LRO), or in various papers and presentations including:
All relevant documentation for the Receiver Algorithms can be found on the ICESat-2 Technical Dat... more All relevant documentation for the Receiver Algorithms can be found on the ICESat-2 Technical Data Management System (TDMS) under the ATLAS Algorithms subsystem. The launch version of the FSW (version 3.1.0) is based upon version 3.7c of this document. The latest version of this document can be found on TDMS under ICESat-2-ALG-PROC-0675. Other related documents, which are currently on the ICESat-2 TDMS, are: The ATLAS Coordinate Systems Descriptions Report, written by Marc Saltzman, is on TDMS under ICESat-2-SYS-RPT-0591. A description of the Simulator is given in the "Guide to the ATLAS Simulator for Users and Programmers" which is on TDMS under ICESat-2-ALG-TN-0577. The document describing the Receiver Algorithms testing is the "ATLAS Receiver Algorithms Test Plan," which explains the tests, including the purpose of each, and how to set each up. This is on TDMS under ICESat-2-ALG-PLAN-0310. The results of the tests described in this document are detailed in the "ATLAS Receiver Algorithms Simulator Test Results" document. This is on TDMS under ICESat-2-ALG-RPT-0659. The latest onboard databases (DEM, DRM, SRM) and their related documentation are on TDMS under ICESat-2-ALG-TN-0362. The latest Receiver Algorithm Parameters are on TDMS under ICESat-2-ALG-SPEC-0255. The Rx Algorithm Parameter Definition Document is on TDMS under ICESat-2-ALG-TN-0876. Changes from v3.2 to v3.3 1-Additional clarification to the NoSig timer state (section 7.4). 2-Change to the calculation of SigLoc in section 5.3 to add 0.5 hwbins or 1 clock cycle. Changes from v3.1 to v3.2 1-In section 5.3 the Algorithms say that if the maximum bin is beyond the last full hardware bin, then the last full software bin should be chosen as the max bin. The Flight Software is not able to do this. We have left the Algorithm as stated, but have written an exception for the FSW. 2-The threshold should be calculated using the threshold function. This has now been explicitly stated in section 5.3. 3-The TEP parameters to be used to define the TEP_NOT region should be converted to start and end and then rounded to the nearest hardware bin boundary. Now stated in section 5.3. 4-Section 5.3 now states that, in the Bnoise calculation, the max bin used should be the one AFTER the TEP_NOT rejections. 5-The calculation of the threshold in section 5.3 has "ceiling" added. 6-In section 7.4 the timer state handling has been clarified, plus other clarifications. 7-The downlink band overlap was clarified in section 7.7. Changes from v3.0 to v3.1 1-In section 7.4 the Telemetry Band Offset usage was clarified for both the NoSig_Timer1 and NoSig_Timer2 cases. Changes from v2.8g to v3.0 1-Due to the leap second being introduced June 30, 2015, GPS-UT1 (aka LS) will become 17 seconds (section 4.3) so this value should now be used as the default. 2-In section 5.4 verbage was added to clarify that the range window being discussed refers to the range window of MF #3 out of the 5 in the Super Frame. 3-In section 7.4 a sentence has been added to clarify which signal location to use if both the primary and tertiary exist. Changes from v2.8d to v2.8g 1-Modified the paragraph related to relief for coastline data (section 7.4). Changes from v2.8d to v2.8f 1-Added some information on the TEP to section 3.10. 2-Corrected the way the PCE delays are being added to the range window (section 4.15). This involves reordering some of the calculations from what was in v2.8d of the document. 3-Changed the conversion of Jrw and Mrw from RWS and RWC in sections 4.16 and 4.17 to use the "ceiling" function instead of "integer" (which is the same as the FORTRAN "floor"). 4-Added note to clip the telemetry band if any part falls outside the range window (section 7.9). 5-Changed the handling of the signal location for the PCE delay in the NoSig_Timer2 case (section 7.4). 6-Changed the handling of the TEP telemetry region for the PCE delay (section 7.5). 7-Updated the Algorithm Parameter files in Appendix F. Changes from v2.8c to v2.8d 1-Cosmetic change to insert a line break between iTEP_flag=0 and next line on page 51. 2-Changed NoSig_Relief1 to NoSig_Scaling in the equation at the top of page 50.
One-way laser ranging technology is applied for the precise orbit determination of LRO, which is ... more One-way laser ranging technology is applied for the precise orbit determination of LRO, which is the first trial for supporting the missions of lunar or planetary spacecraft. In this paper, LRO payload and ground system are discussed for LRO laser ranging, and some errors effecting on time of flight and tracking mount accuracy are analyzed. Additionally several technologies are also analyzed to make laser pulses shot from ground stations to arrive in the LRO earth window. Measurement data of LRO laser ranging verified that these technologies could be implemented for one-way laser ranging of lunar spacecraft.
The SLR2000 Simulator is a software package designed to allow testing of new tracking and ranging... more The SLR2000 Simulator is a software package designed to allow testing of new tracking and ranging algorithms prior to the actual hardware development of NASA’s next generation of Satellite Laser Ranging Systems, called SLR2000. The simulator is written in FORTRAN, currently runs in the HPUX environment, and models relevant errors in the receiver system, tracking mount, weather sensors, station location, system timing, predictions, and others. Recent work includes adding a new signal to noise algorithm, improving the tracking mount model, and developing an acquisition search algorithm. As a consequence of this work, we feel that the simulation results now provide a more realistic example of SLR2000 performance. Simulations of SLR2000 tracking and ranging performance will be presented.
Researchers of NASA's GSFC are currently developing a scanning airborne photon-counting laser alt... more Researchers of NASA's GSFC are currently developing a scanning airborne photon-counting laser altimeter. This paper summarizes the creation of high resolution, precise DEMs from repeat passes of airborne laser scanning surveys to validate this new system. To study coastal erosion several sections of the Atlantic and Pacific coast have been mapped by NASA's Airborne Topographic Mapper (ATM) conical scanning altimeter. We selected two 5 km long and about 1 km wide stretches of the coast in Maryland to create precise Digital Elevation Models. One site is urban area (southern Ocean City) and the other is characterized by coastal marshes and beaches (northern Assateague Island). To obtain a dense data set, we combine laser altimetry data from 21 swaths acquired in 4 different missions. Laser points over planar surfaces, such as flat roofs and parking lots were analyzed to check the the repeatibility of the measurements. The absolute accuracy of the laser scanning was assessed by comparing surfaces extracted from the laser point cloud with GPS and photogrammetry results. These studies confirm the 0.1-0.2 m vertical and submeter horizontal accuracy of the ATM system. At the heart of the interpolation procedure is a bilinear interpolation that determines the surface elevation at the grid posts from planes fitted through the points located within 2 m by 2 m grid cells. Outlier observations are detected by using a robust estimator. The residual of the plane fitting and the uniformity of the distribution of the observations within the grid cells are used to assess the accuracy of the DEM. These parameters suggest an accuracy of 0.3 m or better for 90.4 % of the DEM points on the urban area, and 48.5 % of the points have an accuracy of 0.1 m or better. Similar accuracy is achieved on the site covered by natural vegetation on Assateague Island.
NASA's Space Geodesy Project (SGP) is developing a prototype core site for a next generation ... more NASA's Space Geodesy Project (SGP) is developing a prototype core site for a next generation Space Geodetic Network (SGN). Each of the sites in this planned network co-locate current state-of-the-art stations from all four space geodetic observing systems, GNSS, SLR, VLBI, and DORIS, with the goal of achieving modern requirements for the International Terrestrial Reference Frame (ITRF). In particular, the driving ITRF requirements for this network are 1.0 mm in accuracy and 0.1 mm/yr in stability, a factor of 10-20 beyond current capabilities. Development of the prototype core site, located at NASA's Geophysical and Astronomical Observatory at the Goddard Space Flight Center, started in 2011 and will be completed by the end of 2013. In January 2012, two operational GNSS stations, GODS and GOON, were established at the prototype site within 100 m of each other. Both stations are being proposed for inclusion into the IGS network. In addition, work is underway for the inclusion...
More precise lunar and Martian ranging will enable unprecedented tests of Einstein's theory of Ge... more More precise lunar and Martian ranging will enable unprecedented tests of Einstein's theory of General Relativity and well as lunar and planetary science. NASA is currently planning several missions to return to the Moon, and it is natural to consider if precision laser ranging instruments should be included. New advanced retroreflector arrays at carefully chosen landing sites would have an immediate positive impact on lunar and gravitational studies. Laser transponders are currently being developed that may offer an advantage over passive ranging, and could be adapted for use on Mars and other distant objects. Precision ranging capability can also be combined with optical communications for an extremely versatile instrument. In this paper we discuss the science that can be gained by improved lunar and Martian ranging along with several technologies that can be used for this purpose.
The telescope is designed as a monostatic system to both transmit laser energy and receive light ... more The telescope is designed as a monostatic system to both transmit laser energy and receive light from targeted objects through common optics and a common optical path. The gimbal drives the telescope to track Earth orbiting satellites, stars and fixed ground targets. This subsystem includes the telescope and Coudé path through the tracking subsystem, two cameras mounted on the telescope (one low light camera for viewing dim targets and one wide field of view camera for visual tracking), and all associated environmental monitoring and control devices such as temperature sensors, accelerometers, etc. It also includes the gimbal, encoders, servo electronics, and additional hardware/software to monitor/maintain environmental limits. The gimbal portion of the telescope and gimbal subsystem is attached to a riser which is mounted on a concrete pier and maintains vibrational isolation from other components of the shelter and dome to minimize disturbances to the gimbal pointing and tracking. This subsystem has components in both the dome and the shelter. 4.2. Optical Bench The optical bench (OB) subsystem is designed to allow the laser subsystem, receiver subsystem, and star camera to reside in an environmentally controlled environment, while supporting laser divergence changes for different satellites, point ahead of the laser beam for satellites, beam blocking and beam attenuation for laser safety, system configuration changes for the various modes (star calibration, ground target ranging and satellite tracking), and reduction in the background light that the detector is exposed to (ND wheel, spatial and spectral filters). Laser light is directed along a path on the optical bench that is aligned to the telescope optical axis. The transmitted light goes from the laser to the pit mirror (which is part of the OB subsystem), along the Coudé path, and eventually out through the telescope. Receive light captured by the telescope is directed to the receive path on the optical bench which is also aligned to the telescope optical axis. Finally, this subsystem includes diagnostic components to monitor the laser characteristics and to support alignment. The star camera is part of the optical bench subsystem. The optical bench is contained within the shelter. 4.3. Range Receiver The range receiver subsystem consists of the detector and associated electronics to detect and measure the start and stop event times, support the software s determination of the signal from the background noise and the range to the target, and provide angular offset information to allow for closed loop tracking. The range receiver subsystem also includes the RCE (Range Control Electronics) which provides the software with control of the laser fire frequency, provides the software range gate control for the detector during satellite tracking, and provides fixed ground target range gate control. In addition the range receiver subsystem includes a wide field of view low light Acquisition Camera for use in acquiring targets with poor predictions. Part of this subsystem sits on the optical bench, the rest is in the electronics rack. All are contained within the shelter.
County (UMBC) ScholarWorks@UMBC digital repository on the Maryland Shared Open Access (MD-SOAR) p... more County (UMBC) ScholarWorks@UMBC digital repository on the Maryland Shared Open Access (MD-SOAR) platform. Please provide feedback Please support the ScholarWorks@UMBC repository by emailing [email protected] and telling us what having access to this work means to you and why it's important to you. Thank you.
Lunar Reconnaissance Orbiter (LRO) will be tracked in one-way and two-way modes by microwave and ... more Lunar Reconnaissance Orbiter (LRO) will be tracked in one-way and two-way modes by microwave and optical systems in order to meet its global measurement requirements of 1-m vertical and 50-m horizontal position accuracy. Up to 28 Earth-station laser fires may be received at the antenna-mounted telescope. Earth returns and lunar returns from 5 beams will be time-tagged simultaneously with sub-ns
Laser ranging systems now managed by the NASA Dynamics of the Solid Earth (DOSE) and operated by ... more Laser ranging systems now managed by the NASA Dynamics of the Solid Earth (DOSE) and operated by the Bendix Field Engineering Corporation, the University of Hawaii, and the University of Texas, have produced a wealth of inter-disciplinary scientific data over the last three decades. Despite upgrades to the most of the ranging station subsystems, the control computers remain a mix of 1970s-vintage minicomputers. These encompass a wide range of vendors, operating systems, and languages, making hardware and software support increasingly difficult. Current technology allows replacement of controller computers at a relatively low cost while maintaining excellent processing power and a friendly operating environment. The new controller systems are now being designed using IBM-PC-compatible 80486-based microcomputers, a real-time Unix operating system (LynxOS), and X-windows/Motif graphical user interface. Along with this, a flexible hardware design using CAMAC, GPIB, and serial interfaces has been chosen. This design supports minimizing short and long term costs by relying on proven standards for both hardware and software components. Currently, the project is in the design and prototyping stage with the first systems targeted for production in mid-1993.
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