VHF broadband digital interferometer

Morimoto, Takeshi; Kawasaki, Zen

doi:10.1002/tee.20030

Cited by 5 publications

(3 citation statements)

References 7 publications

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“…Moreover, uncertainty also exists in estimating the extension length and velocity of the lightning channel. Therefore, 3D mapping of the VHF interferometry is needed, and many methods have been proposed at present, such as synchronous observation of dual station interferometers [31][32][33][34], synchronous observation of an interferometer with a high-speed camera [35] or acoustic array [36], and the combination of 3D structures provided by the LMA and higher-timeresolution 2D mapping of an interferometer [27]. The combination of different detection objects or different mapping technologies may have the problem of inconsistent temporal resolution and thus reduce the temporal and spatial resolution of the final 3D mapping results.…”

Section: Introductionmentioning

confidence: 99%

Three-Dimensional Mapping on Lightning Discharge Processes Using Two VHF Broadband Interferometers

et al. 2022

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Lightning Very-high-frequency (VHF) broadband interferometer has become an effective approach to map lightning channels in two dimensions with high time resolution. This paper reports an approach to mapping lightning channels in three dimensions (3D) using two simultaneous interferometers separated by about 10 km. A 3D mapping algorithm was developed based on the triangular intersection method considering the location accuracy of both interferometers and the arrival time of lightning VHF radiation. Simulation results reveal that the horizontal and vertical location errors within 10 km of the center of the two stations are less than 500 m and 700 m, respectively. The 3D development of an intra-cloud (IC) lightning flash and a negative cloud-to-ground (-CG) lightning flash with two different ground terminations in the same thunderstorm are reconstructed, and the extension direction and speed of lightning channels are estimated consequently. Both IC and CG flash discharges showed a two-layer structure in the cloud with discharges occurring in the upper positive charge region and the lower negative charge region, and two horizontally separated positive charge regions were involved in the two flashes. The average distance of the CG ground terminations between the interferometer results and the CG location system was about 448 m. Although disadvantages may still exist in 3D real-time location compared with the lightning mapping array system working with the principle of the time of arrival, interferometry with two or more stations has the advantage of lower station number and is feasible in regions with poor installation conditions, such as heavy-radio-frequency-noise regions or regions that are difficult for the long-baseline location system.

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Section: Introductionmentioning

confidence: 99%

Three-Dimensional Mapping on Lightning Discharge Processes Using Two VHF Broadband Interferometers

et al. 2022

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“…Compared with TDOA locating system, the lightning interferometer can not only locate isolated pulse signals but continuous emissions as well [28], and the time resolution of the locating result can reach or exceed microsecond level, the calculated phase difference spectrum was unwrapped, the angle of incidence was calculated by using the phase difference of each frequency point in the stronger frequency band of the signal, and was given as the calculation result after averaging. Similar practices are often used in existing similar systems [32,[36][37][38]. In recent years, with the appearance of continuous interferometers, the 2-D locating method has also changed.…”

Section: Introductionmentioning

confidence: 99%

“…Even if the 3-D information can be estimated by combining the information provided by other synchronous observation systems [22,30,31], there is still an inconvenience and uncertainty in the study of the physical mechanism of discharge. How to use multi-station synchronous 3-D observation to give full play to the advantages of interferometer system is always a problem faced in interferometer observation, and many attempts have been made continuously to overcome this [34][35][36]. This paper introduces a 3-D locating method of a two-station broadband interferometer system and gives the corresponding error analysis and observation results.…”

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confidence: 99%

The Three-Dimensional Locating of VHF Broadband Lightning Interferometers

2018

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VHF (Very High Frequency) lightning interferometers can locate and observe lightning discharges with a high time resolution. Especially the appearance of continuous interferometers makes the 2-D location of interferometers further improve in time resolution and completeness. However, there is uncertainty in the conclusion obtained by simply analyzing the 2-D locating information. Without the support of other 3-D total lightning locating networks, the 2-station interferometer becomes an option to obtain 3-D information. This paper introduces a 3-D lightning location method of a 2-station broadband interferometer, which uses the theodolite wind measurement method for reference, and gives the simulation results of the location accuracy. Finally, using the multi-baseline continuous 2-D locating method and the 3-D locating method, the locating results of one intra-cloud flash and the statistical results of the initiation heights of 61 cloud-to-ground flashes and 80 intra-cloud flashes are given. The results show that the two-station interferometer has high observation accuracy on both sides of the connection between the two sites. The locating accuracy will deteriorate as the distance between the radiation source and the two stations increases or the height decreases. The actual locating results are similar to those of the existing VHF TDOA (Time Difference of Arrival) lightning locating network.which is much higher than that of the existing TDOA locating system [29]. Although these advantages can only be fully demonstrated when the interferometer is used for azimuth-elevation 2-D direction finding, the high time resolution 2-D locating of the interferometer can be used for networking observation or in combination with another set of lightning locating system to give full play to its characteristics and describe the lightning discharge process in detail [23,30,31]. Currently, the existing lightning interferometers can be roughly divided into two types: narrow-band interferometers and wide-band interferometers, depending on the bandwidth of the received signals [6,32]. The observed performance of the two types of equipment is similar, but the broadband interferometer can record the VHF broadband radiation waveform of lightning, and can use various digital signal processing methods to optimize the locating results afterward [29,33]. Especially the continuous interferometer using high-speed Analog to Digital (A/D) data acquisition card at present has a high time resolution, a large dynamic range of signal amplitude resolution and continuous sampling recording ability, making the new interferometer able to describe the lightning discharge processes more completely [29].A single-station broadband interferometer system can only give the locating results of the radiation sources in two dimensions, with which many conclusions can be made based on the estimation. Even if the 3-D information can be estimated by combining the information provided by other synchronous observation systems [22,30,31], there is still an inconvenienc...

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