Empirical Phase Calibration for Multistatic Specular Meteor Radars Using a Beamforming Approach

Chau, Jorge L.; Clahsen, Matthias

doi:10.1029/2018rs006741

Cited by 21 publications

(19 citation statements)

References 31 publications

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“…The PSF reported in Chau and Clahsen (2019, Fig. 1) match with the morphology of the Monte-Carlo simulations of DOA determination performed here and in Kastinen and Kero (2020).…”

supporting

confidence: 73%

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Resolving ambiguous direction of arrival of weak meteor radar trail echoes

Kastinen¹,

Kero²,

Kozlovsky³

et al. 2020

Preprint

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Abstract. Meteor phenomena cause ionized plasmas that can be roughly divided into two distinctly different regimes: a dense and transient plasma region co-moving with the ablating meteoroid and a trail of diffusing plasma left in the atmosphere and moving with the neutral wind. Interferometric radar systems are used to observe the meteor trails and determine their positions and drift velocities. Depending on the spatial configuration of the receiving antennas and their individual gain patterns, the voltage response can be the same for several different plane wave Directions Of Arrival (DOA), thereby making it impossible to determine the correct direction. Noise can create the same effect even if the system contains no theoretical ambiguities. We propose a method for interferometric meteor trail radar data analysis using coherent integration of the signal spatial correlation to resolve DOA ambiguities. We have validated the method by a combination of Monte Carlo simulations and application on 10 minutes of measurement data (174 meteor events) obtained with the Sodankylä Geophysical Observatory SKiYMET all-sky interferometric meteor radar. We also applied a Bayesian method to determine the true location of ambiguous events in the data set. In 26 out of 27 (~ 96 %) ambiguous cases, the coherently integrated spatial correlation gave the correct output DOA as determined by Bayesian inference. In the one case that was mis-classified there were not enough radar pulses to coherently integrate for the method to be effective.

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“…The PSF reported in Chau and Clahsen (2019, Fig. 1) match with the morphology of the Monte-Carlo simulations of DOA determination performed here and in Kastinen and Kero (2020).…”

supporting

confidence: 73%

“…signal channel, the PSF is identical for all input DOAs. The identification done in Chau and Clahsen (2019) thereby apply for all input DOA.…”

mentioning

confidence: 99%

Resolving ambiguous direction of arrival of weak meteor radar trail echoes

Kastinen¹,

Kero²,

Kozlovsky³

et al. 2020

Preprint

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“…Namely, the AOD is obtained from the cross correlation of the complex voltages corresponding to different transmitting antennas, while the Doppler and correlation times are obtained from the averaged autocorrelation. The AOD estimation was done using a combination of beam forming and a complex fitting approach (e.g., Vaudrin et al, 2018;Chau and Clahsen, 2019). Given the relatively long baselines of the pentagon configuration, the altitude information was also used to remove angular ambiguities on low-elevation echoes.…”

Section: Miso-cw Resultsmentioning

confidence: 99%

“…The phase difference between receivers m and n needs to be removed before the AOAs are estimated. Either they are measured using common feeding lines or echoes from targets with well-known locations, or they are empirically estimated using the expected distribution of underdense specular meteor echoes (e.g., Valentic et al, 1997;Hocking et al, 2001;Holdsworth et al, 2004b;Lau et al, 2006;Chau et al, 2008;Chau and Clahsen, 2019).…”

Section: Interferometry In Standard Specular Meteor Radarsmentioning

confidence: 99%

Novel specular meteor radar systems using coherent MIMO techniques to study the mesosphere and lower thermosphere

et al. 2019

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Abstract. Typical specular meteor radars (SMRs) use one transmitting antenna and at least a five-antenna interferometric configuration on reception to study the mesosphere and lower thermosphere (MLT) region. The interferometric configuration allows the measurement of the angle-of-arrival (AOA) of the detected meteor echoes, which in turn is needed to derive atmospheric parameters (e.g., mean winds, momentum fluxes, temperatures, and neutral densities). Recently, we have shown that coherent MIMO configurations in atmospheric radars, i.e., multiple input (transmitters) and multiple output (receivers), with proper diversity in transmission can be used to enhance interferometric atmospheric and ionospheric observations. In this study we present novel SMR systems using multiple transmitters in interferometric configuration, each of them employing orthogonal pseudorandom coded transmitted sequences. After proper decoding, the angle of departure (AOD) of the detected meteor echoes with respect to the transmitter site are obtained at each receiving antenna. We present successful bistatic implementations of (1) five transmitters and one receiver using coded continuous wave (CW) (MISO-CW), and (2) five transmitters and five receivers using coded CW (MIMO-CW). The latter system allows simultaneous independent observations of the specular meteor trails with respect to the transmitter (AOD) and with respect to the receiver (AOA). The quality of the obtained results is evaluated in terms of the resulting mean winds, the number of detections and the daily diffusion trail vs. altitude behavior. We show that the proposed configurations are good alternatives to explore the MLT region. When combined with multi-static approaches, they can increase the number of meteor detections, thereby improving the quality of atmospheric estimates and allowing the measurement of new atmospheric parameters (e.g., horizontal divergence, vorticity), The use of multiple collocated transmitters for interferometric AOD determination makes building a multi-static radar network easier logistically, as only one receiver per receiving site antenna is sufficient.

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“…The Holdsworth (2005) approach determines the offsets to apply to the phase differences between the centre and each of the other receive antenna channels that maximise the number of meteors within a range of heights that the meteors are expected to occur (see Chau and Clahsen (2019) for a generalized approach to this). For the BP system, we have used minimum and maximum permissible heights of 70 and 110 km, respectively, and 70 and 120 km for the Mylor system.…”

mentioning

confidence: 99%

Multistatic meteor radar observations of gravity wave-tidal interaction over Southern Australia

Spargo¹,

MacKinnon²

2019

Preprint

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This paper assesses the ability of a recently-installed 55 MHz multistatic meteor radar to measure gravity wave-driven momentum fluxes around the mesopause, and applies it in a case study of measuring gravity wave forcing on the diurnal tide during a period following the autumnal equinox of 2018. The radar considered is in the vicinity of Adelaide, South Australia (34.9 • S, 138.6 • E) and consists of a monostatic radar and bistatic receiver separated by approximately 55 km. 5The assessment shows that the inclusion of the bistatic receiver reduces the relative uncertainty of the momentum flux estimate from about 75% to 65% (for a flux magnitude of ∼ 20 m 2 s −2 , one day's worth of integration, and for a gravity wave field synthesized from a realistic spectral model). This increase in precision appears to be entirely attributable to the increased number of meteor detections associated with the combined monostatic and bistatic receivers, rather than changes in the meteors' spatial distribution. 10The case study reveals large modulations in the diurnal tidal amplitudes, with a maximum tidal amplitude of ∼ 50 ms −1 and an associated maximum zonal wind velocity of around 140 ms −1 . While the observed gravity wave forcing exhibits a complex relationship with the tidal winds during this period, the components of the forcing are seen to be approximately out of phase with the tidal winds above 88 km. No clear phase relationship has been observed below 88 km.

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Empirical Phase Calibration for Multistatic Specular Meteor Radars Using a Beamforming Approach

Cited by 21 publications

References 31 publications

Resolving ambiguous direction of arrival of weak meteor radar trail echoes

Resolving ambiguous direction of arrival of weak meteor radar trail echoes

Novel specular meteor radar systems using coherent MIMO techniques to study the mesosphere and lower thermosphere

Multistatic meteor radar observations of gravity wave-tidal interaction over Southern Australia

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