A single-frequency Motorola Global Positioning System (GPS) receiver was launched with the Extrem... more A single-frequency Motorola Global Positioning System (GPS) receiver was launched with the Extreme Ultraviolet Explorer mission in June 1992. The receiver utilizes dual GPS antennas placed on opposite sides of the satellite to obtain full GPS coverage as it rotates during its primary scanning mission. A data set from this GPS experiment has been processed at the Jet Propulsion Laboratory with the GIPSY-OASIS 2 software package. The single-frequency, dual antenna approach and the low altitude (approximately 500 km) orbit of the satellite create special problems for the GPS orbit determination analysis. The low orbit implies that the dynamics of the spacecraft will be difficult to model, and that atmospheric drag will be an important error source. A reduced-dynamic solution technique was investigated in which ad hoc accelerations were estimated at each time step to absorb dynamic model error. In addition, a single-frequency ionospheric correction was investigated, and a cycle-slip detector was written. Orbit accuracy is currently better than 5 m. Further optimization should improve this to about 1 m.
A preliminary design for a codeless GPS receiver intended for orbit determination of light satell... more A preliminary design for a codeless GPS receiver intended for orbit determination of light satellites is presented. The basic approach is to have the LIGHTSAT and a network of automated ground stations operated in a differential mode by common viewing of essentially the same GPS space vehicles. The LIGHTSAT and the ground reference network would utilize the same type of codeless receivers and therefore would be functional even in the presence of selective availability/anti-spoof (SA/A-S) transmissions from the GPS satellites. Results of a covariance study done with the JPL OASIS software are presented for a scenario of rapid orbit determination soon after orbital insertion of the LIGHTSAT with such a codeless GPS receiver.
... BIOGRAPHY Kenn Gold is the Vice President of Engineering of at NAVSYS Corporation and the Pro... more ... BIOGRAPHY Kenn Gold is the Vice President of Engineering of at NAVSYS Corporation and the Product Area Manager for the Advanced ... Aghssim outputs the raw signal amplitude, code phase, and carrier phase information needed to generate the C/A and P(Y) code signals. ...
... The combined digital array signal, z(t), is generated from summing the weighted individual fi... more ... The combined digital array signal, z(t), is generated from summing the weighted individual filtered digital antenna element (DAE) signals. ... Page 5. 5 GPS. The DAE can currently accommodate either L1 or L2 signals and a future upgrade is planned to add the L5 signal. ...
Space-based GPS technology presents several significant challenges over Earth based systems. Thes... more Space-based GPS technology presents several significant challenges over Earth based systems. These include visibility issues for rotating platforms, and tracking of GPS satellites from spacecraft that are in higher orbits than the GPS. Kinematic relative position in orbit also presents challenges in resolving carrier phase ambiguities in real time. NAVSYS has developed a digital GPS receiver that makes use of 3-dimensional Digital Beam Steering technology. This offers several advantages including:
Altimetry data has been used extensively to acquire data about characteristics of the Earth, the ... more Altimetry data has been used extensively to acquire data about characteristics of the Earth, the Moon, and Mars. More recently, the idea of using altimetry for orbit determination has also been explored. This report discusses modifications to JPL's GIPSY/OASIS II software to include altimetry data as an observation type for precise orbit determination. The mathematical foundation of using altimetry for
PLANS 2004. Position Location and Navigation Symposium (IEEE Cat. No.04CH37556), 2004
... through the vehicle's data link and also requires knowledge of the local tro... more ... through the vehicle's data link and also requires knowledge of the local tropospheric and ionospheric ... This failure mode can best be detected through spatial processing to detect the angle of ... The residual effect of the multipath on the signals after applying the digital weights can ...
ABSTRACT NAVSYS Corporation has developed a 109-element GPS antenna array and a modified version ... more ABSTRACT NAVSYS Corporation has developed a 109-element GPS antenna array and a modified version of the High-gain Advanced GPS Receiver (HAGR) which can perform beam steering with the digitally-combined signals from each antenna element. If adequate gain can be obtained from reflected GPS signals, applications involving Earth mapping, ocean surface mapping, terrain modeling, digital mapping, and other passive monitoring uses can benefit. Previous research in such uses of reflected GPS has been done at NAVSYS with a 16-element antenna array to sense the reflected signal. This paper describes the design of a 109-element Digital Beam-Steered Antenna Array and the collection of a data set to test the concept of operation.
The Software Defined Radio (SDR) is an enabling technology that is being leveraged across a wide ... more The Software Defined Radio (SDR) is an enabling technology that is being leveraged across a wide range of areas within the wireless industry to provide efficient and comparatively inexpensive solutions to several constraints posed in current systems. Since SDR-enabled user devices and network equipment can be dynamically programmed in software, this allows them to be adapted to provide richer feature sets and introduce advanced new services that provide more choices to the end-user and new revenue streams for the service provider. In this paper, the principle of operation of a Software GPS Receiver, designed for embedding within a Software Defined Radio, is described and test results are presented showing the operation of an SDR test-bed in generating the modernized GPS signals.
Precision orbit determination for the Geosat Follow-On satellites. Kelly Irish, Kenn Gold, George... more Precision orbit determination for the Geosat Follow-On satellites. Kelly Irish, Kenn Gold, George Born, Angela Reichert, Penina Axelrad Journal of Spacecraft and Rockets 35:33, 336-341, 5/1998. The potential radial orbit accuracy ...
A single-frequency Motorola Global Positioning System (GPS) receiver was launched with the Extrem... more A single-frequency Motorola Global Positioning System (GPS) receiver was launched with the Extreme Ultraviolet Explorer mission in June 1992. The receiver utilizes dual GPS antennas placed on opposite sides of the satellite to obtain full GPS coverage as it rotates during its primary scanning mission. A data set from this GPS experiment has been processed at the Jet Propulsion Laboratory with the GIPSY-OASIS 2 software package. The single-frequency, dual antenna approach and the low altitude (approximately 500 km) orbit of the satellite create special problems for the GPS orbit determination analysis. The low orbit implies that the dynamics of the spacecraft will be difficult to model, and that atmospheric drag will be an important error source. A reduced-dynamic solution technique was investigated in which ad hoc accelerations were estimated at each time step to absorb dynamic model error. In addition, a single-frequency ionospheric correction was investigated, and a cycle-slip detector was written. Orbit accuracy is currently better than 5 m. Further optimization should improve this to about 1 m.
A preliminary design for a codeless GPS receiver intended for orbit determination of light satell... more A preliminary design for a codeless GPS receiver intended for orbit determination of light satellites is presented. The basic approach is to have the LIGHTSAT and a network of automated ground stations operated in a differential mode by common viewing of essentially the same GPS space vehicles. The LIGHTSAT and the ground reference network would utilize the same type of codeless receivers and therefore would be functional even in the presence of selective availability/anti-spoof (SA/A-S) transmissions from the GPS satellites. Results of a covariance study done with the JPL OASIS software are presented for a scenario of rapid orbit determination soon after orbital insertion of the LIGHTSAT with such a codeless GPS receiver.
... BIOGRAPHY Kenn Gold is the Vice President of Engineering of at NAVSYS Corporation and the Pro... more ... BIOGRAPHY Kenn Gold is the Vice President of Engineering of at NAVSYS Corporation and the Product Area Manager for the Advanced ... Aghssim outputs the raw signal amplitude, code phase, and carrier phase information needed to generate the C/A and P(Y) code signals. ...
... The combined digital array signal, z(t), is generated from summing the weighted individual fi... more ... The combined digital array signal, z(t), is generated from summing the weighted individual filtered digital antenna element (DAE) signals. ... Page 5. 5 GPS. The DAE can currently accommodate either L1 or L2 signals and a future upgrade is planned to add the L5 signal. ...
Space-based GPS technology presents several significant challenges over Earth based systems. Thes... more Space-based GPS technology presents several significant challenges over Earth based systems. These include visibility issues for rotating platforms, and tracking of GPS satellites from spacecraft that are in higher orbits than the GPS. Kinematic relative position in orbit also presents challenges in resolving carrier phase ambiguities in real time. NAVSYS has developed a digital GPS receiver that makes use of 3-dimensional Digital Beam Steering technology. This offers several advantages including:
Altimetry data has been used extensively to acquire data about characteristics of the Earth, the ... more Altimetry data has been used extensively to acquire data about characteristics of the Earth, the Moon, and Mars. More recently, the idea of using altimetry for orbit determination has also been explored. This report discusses modifications to JPL's GIPSY/OASIS II software to include altimetry data as an observation type for precise orbit determination. The mathematical foundation of using altimetry for
PLANS 2004. Position Location and Navigation Symposium (IEEE Cat. No.04CH37556), 2004
... through the vehicle's data link and also requires knowledge of the local tro... more ... through the vehicle's data link and also requires knowledge of the local tropospheric and ionospheric ... This failure mode can best be detected through spatial processing to detect the angle of ... The residual effect of the multipath on the signals after applying the digital weights can ...
ABSTRACT NAVSYS Corporation has developed a 109-element GPS antenna array and a modified version ... more ABSTRACT NAVSYS Corporation has developed a 109-element GPS antenna array and a modified version of the High-gain Advanced GPS Receiver (HAGR) which can perform beam steering with the digitally-combined signals from each antenna element. If adequate gain can be obtained from reflected GPS signals, applications involving Earth mapping, ocean surface mapping, terrain modeling, digital mapping, and other passive monitoring uses can benefit. Previous research in such uses of reflected GPS has been done at NAVSYS with a 16-element antenna array to sense the reflected signal. This paper describes the design of a 109-element Digital Beam-Steered Antenna Array and the collection of a data set to test the concept of operation.
The Software Defined Radio (SDR) is an enabling technology that is being leveraged across a wide ... more The Software Defined Radio (SDR) is an enabling technology that is being leveraged across a wide range of areas within the wireless industry to provide efficient and comparatively inexpensive solutions to several constraints posed in current systems. Since SDR-enabled user devices and network equipment can be dynamically programmed in software, this allows them to be adapted to provide richer feature sets and introduce advanced new services that provide more choices to the end-user and new revenue streams for the service provider. In this paper, the principle of operation of a Software GPS Receiver, designed for embedding within a Software Defined Radio, is described and test results are presented showing the operation of an SDR test-bed in generating the modernized GPS signals.
Precision orbit determination for the Geosat Follow-On satellites. Kelly Irish, Kenn Gold, George... more Precision orbit determination for the Geosat Follow-On satellites. Kelly Irish, Kenn Gold, George Born, Angela Reichert, Penina Axelrad Journal of Spacecraft and Rockets 35:33, 336-341, 5/1998. The potential radial orbit accuracy ...
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