13:45 〜 15:15
[MIS24-P06] The Application of Time Delay Calibration in High-Sampling-Rate Broadband Interferometer locating Observation
キーワード：lightning, VHF broadband lightning interferometer, lightning locating
In order to further improve the time resolution of observations, this paper introduces a time-delay calibration technology based on existing high-sampling-rate VHF broadband lightning interferometer observation data and attempts to use smaller positioning time windows and sliding intervals to analyze the effects of time-delay calibration technology on localization calculations.
The data is from the broadband interferometer lightning observation conducted in Guangdong in 2010. The observation was conducted using a 15-meter square observation array composed of four broadband discone antennas. The system used a Lecroy7100A oscilloscope with a sampling rate of 1GS/s and segmented trigger mode to collect lightning signals in the 30-300MHz frequency band. The segmented trigger mode divided the 10M-byte memory of each channel of the oscilloscope into 5000 segments. The dead time between segments was usually around 2-3us. This article used an existing two-dimensional single-station positioning method, which estimated the time delay for multiple baselines and then used the least squares method to solve for the position.
A negative cloud-to-ground (CG) flash was observed at the CongHua Meteorological Bureau observation station at 15:40:06 on June 13, 2010. The system recorded the fast-changing (time constant of 1ms) ground electric field and a total of 2981 segments of VHF data of the lightning. Figure 1 shows a comparison of the two-dimensional localization results before and after the delay calibration. The color of the radiation source corresponds to the time it occurred.
Figure 1(a) shows the calculation result using a 128 ns analysis window and 32 ns sliding window, while Figure 1(b) shows the locating result after the time delay calibration. Compared with Figure 1(a), the number of points increased from the original 37,134 to 56,115 after the time delay calibration. The large amount of invalid noise points in the original results have disappeared, except for a few scattered blue dots above the main distribution area of the radiation sources. The use of the time delay calibration method has solved the problem of a large number of invalid noise points in the localization results when using a small data analysis window, thereby reducing the number of relevant radiation sources within the window while improving the time resolution of the location results. Subsequent analysis shows that time delay calibration significantly improves the correlation coefficient obtained by cross-correlation calculation.
According to the analysis results in this paper, the following conclusions can be drawn: (1) The use of time delay calibration method can solve the problem of increased noise in the positioning results when the data analysis window length is small under the condition of 1 GS/s sampling rate, improve the positioning effect under small data analysis window conditions, and improve the time resolution of the positioning results while reducing the number of related radiation sources in the window. (2) After using the time delay calibration method, the correlation coefficient obtained by cross-correlation calculation in the positioning calculation process with a small data analysis window length is significantly improved. That is, the method improves the consistency of the signals in the analysis window, makes the input information of the positioning calculation more stable and reasonable, and improves the quality of the positioning calculation output results.
The data is from the broadband interferometer lightning observation conducted in Guangdong in 2010. The observation was conducted using a 15-meter square observation array composed of four broadband discone antennas. The system used a Lecroy7100A oscilloscope with a sampling rate of 1GS/s and segmented trigger mode to collect lightning signals in the 30-300MHz frequency band. The segmented trigger mode divided the 10M-byte memory of each channel of the oscilloscope into 5000 segments. The dead time between segments was usually around 2-3us. This article used an existing two-dimensional single-station positioning method, which estimated the time delay for multiple baselines and then used the least squares method to solve for the position.
A negative cloud-to-ground (CG) flash was observed at the CongHua Meteorological Bureau observation station at 15:40:06 on June 13, 2010. The system recorded the fast-changing (time constant of 1ms) ground electric field and a total of 2981 segments of VHF data of the lightning. Figure 1 shows a comparison of the two-dimensional localization results before and after the delay calibration. The color of the radiation source corresponds to the time it occurred.
Figure 1(a) shows the calculation result using a 128 ns analysis window and 32 ns sliding window, while Figure 1(b) shows the locating result after the time delay calibration. Compared with Figure 1(a), the number of points increased from the original 37,134 to 56,115 after the time delay calibration. The large amount of invalid noise points in the original results have disappeared, except for a few scattered blue dots above the main distribution area of the radiation sources. The use of the time delay calibration method has solved the problem of a large number of invalid noise points in the localization results when using a small data analysis window, thereby reducing the number of relevant radiation sources within the window while improving the time resolution of the location results. Subsequent analysis shows that time delay calibration significantly improves the correlation coefficient obtained by cross-correlation calculation.
According to the analysis results in this paper, the following conclusions can be drawn: (1) The use of time delay calibration method can solve the problem of increased noise in the positioning results when the data analysis window length is small under the condition of 1 GS/s sampling rate, improve the positioning effect under small data analysis window conditions, and improve the time resolution of the positioning results while reducing the number of related radiation sources in the window. (2) After using the time delay calibration method, the correlation coefficient obtained by cross-correlation calculation in the positioning calculation process with a small data analysis window length is significantly improved. That is, the method improves the consistency of the signals in the analysis window, makes the input information of the positioning calculation more stable and reasonable, and improves the quality of the positioning calculation output results.