Antennas

Maqsood, Moazam; Gao, Steven; Montenbruck, Oliver

doi:10.1007/978-3-319-42928-1_17

Cited by 15 publications

(6 citation statements)

References 42 publications

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“…GPS attitude determination in space was first demonstrated in the early 1990s as part of the RADCAL (Radar Calibration) mission and was later applied on a variety of other missions such as APEX, REX-II, UoSat-12, TopSat, and Flying Laptop (see, e.g., Georgi 2017;Hauschild et al 2019, and references therein). On the International Space Station (ISS), a four-antenna GPS receiver system coupled with an inertial measurement unit is used to provide attitude information on a routine basis.…”

Section: Attitude Determinationmentioning

confidence: 99%

CASSIOPE orbit and attitude determination using commercial off-the-shelf GPS receivers

et al. 2019

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As part of the "GPS Attitude, Positioning, and Profiling experiment (GAP)" of the Canadian CASSIOPE science and technology mission, a set of four geodetic GPS receivers connected to independent antennas on the top-panel of the spacecraft can be operated concurrently to collect dual-frequency code and phase measurements on both the L1 and L2 frequencies. The qualification of the commercial off-the-shelf (COTS) GPS receivers is discussed, and flight results of precise orbit and attitude determination are presented. Pseudorange and carrier phase errors amount to roughly 65 cm and 8 mm for the ionospherefree dual-frequency combination, which compares favorably with other missions using fully qualified space GPS receivers and is mainly limited by choice of simple patch antennas without choke rings. Precise orbit determination of CASSIOPE using GPS observations can achieve decimeter-level accuracy during continued operations but suffers from onboard and mission restrictions that limit the typical data availability to less than 50% of each day and induce regular long-duration gaps of 4-10 h. Based on overlap analyses, daily peak orbit determination errors can, however, be confined to 1 m 3D on 84% of all days, which fulfills the mission needs for science data processing of other instruments. The attitude of CASSIOPE can be determined with a representative precision of about 0.2° in the individual axes using three GAP receivers and antennas. Availability of dual-frequency measurements is particularly beneficial and enables single-epoch ambiguity fixing in about 97% of all epochs. Overall, the GAP experiment demonstrates the feasibility of using COTS-based global navigation satellite system receivers in space and the benefits they can bring for small-scale science missions.

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Section: Attitude Determinationmentioning

confidence: 99%

CASSIOPE orbit and attitude determination using commercial off-the-shelf GPS receivers

et al. 2019

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“…1 using synchronized carriers. Similar to GPS and other GLONASS satellites, both arrays are composed of 12 helix antennas arranged in an inner ring of four elements and an outer ring of eight elements to obtain an M-type gain pattern with a uniform flux over the entire surface of the Earth (Maqsood et al 2017). Constant envelope multiplexing concepts enabling joint transmission of FDMA and CDMA signals through a common amplifier and antenna are presented in Biryukov (2018) and Bakitko (2021), but not required on R803 and mainly considered for future versions of GLONASS-K satellites with a single navigation antenna.…”

Section: Introductionmentioning

confidence: 99%

GLONASS-K2 signal analysis

Thoelert,

Steigenberger,

Montenbruck

2024

GPS Solut

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K2 is a new generation of GLONASS satellites that provides code division multiple access (CDMA) signals in the L1, L2 and L3 frequency bands in addition to legacy L1 and L2 signals based on frequency division multiple access (FDMA) modulation. The first GLONASS-K2 satellite was launched in August 2023 and started signal transmission in early September 2023. Based on measurements with a 30-m high-gain antenna, spectral characteristics of the various signal components are described and relative power levels are identified. A 3 dB (L1) to 4 dB (L2) higher total power is determined for the CDMA signal compared to the legacy FDMA signal and an equal power of the open service and secured CDMA signal components is found. The ranging code of the L2 channel for service information, which has not been publicly disclosed so far, is identified as a Gold code sequence consistent with the data channel of the L1 open service CDMA signal. The high-gain antenna measurements are complemented by tracking data from terrestrial receivers that enable a first assessment of user performance. An up to 50% improvement in terms of noise and multipath performance is demonstrated for the new L1 and L2 CDMA signals in comparison with their legacy counterpart, but no obvious differences between the different binary phase-shift keying and binary offset carrier modulations of the data and pilot components of these signals could be identified for the test stations. Triple-frequency carrier phase observations from L1, L2, and L3 CDMA signals exhibit good consistency at the noise and multipath level, except for small variations that can be attributed to slightly different antenna phase patterns on the individual frequencies. Overall, the new CDMA signals are expected to notably improve and facilitate precise point positioning applications once fully deployed across the GLONASS constellation.

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“…In such radiofrequency systems, antennas are key elements because, by transforming electromagnetic waves into voltage, they essentially represent an interface between the incoming GNSS signals and the GNSS receiver. For more fundamental information regarding GNSS transmitter and receiver antennas, their design, and performance aspects, interested readers are referred to [2,3]. Today, many GNSS applications require millimeter accuracy, but for such requirements to be fulfilled, all influential factors down to the centimeter and millimeter level need to be understood and accounted for.…”

Section: Introductionmentioning

confidence: 99%

“…As the antenna PC is, generally, within the antenna, it is unreachable, and its connection to a physical point or "conventional" terrestrial measurements is needed. However, due to the antenna's physical and electromagnetic properties [2], its PC is changing and varies depending on the incoming GNSS signal's direction, frequency, and intensity and, as such, deviates from an ideal omnidirectional radiation pattern [5][6][7][8][9]. Fundamentally, every incoming signal has its own electrical PC.…”

Section: Introductionmentioning

confidence: 99%

GNSS Receiver Antenna Absolute Field Calibration System Development: Testing and Preliminary Results

Tupek,

Zrinjski,

Švaco

et al. 2023

Remote Sensing

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For high-precision Global Navigation Satellite Systems (GNSS) positioning based on carrier-phase measurements, knowledge of the GNSS receiver antenna electrical signal reception characteristics, i.e., phase center, is crucial. Numerous studies have led to the understanding of the influence of GNSS receiver antenna phase center corrections (PCCs) on GNSS positioning accuracy and other estimated parameters (e.g., receiver clock estimates, ambiguities, etc.). With the goal of determining the PCC model of GNSS receiver antennas, only a few antenna calibration systems/facilities are in operation or under development worldwide. The International GNSS Service (IGS) publishes type-mean PCC models for almost all geodetic-grade GNSS antennas. However, the type-mean models are not perfect and do not fully reflect the signal reception properties of individual GNSS receiver antennas. Relevant published scientific research has shown that the application of individual PCC models significantly improves the accuracy of GNSS positioning and other estimated parameters. In this article, the new automated GNSS antenna calibration system, recently developed at the Laboratory for Measurements and Measuring Technique (LMMT) of the Faculty of Geodesy of the University of Zagreb in Croatia, is presented. The developed system is an absolute field calibration system based on the utilization of a Mitsubishi MELFA 6-axis industrial robot. During calibration, the robot tilts and rotates the GNSS antenna under test (AUT) around a fixed point within the antenna. The antenna PCC modelling is based on time-differenced double-difference carrier-phase observations. Our preliminary results for the Global Positioning System (GPS) L1 (G01) frequency show a submillimeter repeatability of the estimated PCC model and a submillimeter agreement with the Geo++ GmbH calibration results.

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Antennas

Cited by 15 publications

References 42 publications

CASSIOPE orbit and attitude determination using commercial off-the-shelf GPS receivers

CASSIOPE orbit and attitude determination using commercial off-the-shelf GPS receivers

GLONASS-K2 signal analysis

GNSS Receiver Antenna Absolute Field Calibration System Development: Testing and Preliminary Results

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