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Old 14-04-2022, 11:47 AM
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sheeny (Al)
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Join Date: Jun 2005
Location: Oberon NSW
Posts: 14,287
So far I've been concentrating on finding meteor signals and then analysing them, but this is a very slow process.


I've cooked up a process to speed up detection, which I have just started using.


First I tile the EHZ (seismic) and HDF (infrasound) helicorders from the RS&B side by side in SWARM software.


Then I set up a 0.5 Hz to 10Hz bandpass filter on the infrasound channel to eliminate as much noise as possible that doesn't relate to meteors. In the past I've been scanning the raw signal for possible meteors, so I think this should make more meteors detectible.


Then I set the zoom time span to about 15 minutes so I can scan each 30 minute line on the helicorder in two goes, and I look for small sharp spikes which are equally balanced above and below zero, and note the time to the nearest minute. I come back to that later. The first screen shot below shows what this looks like.


After scanning as much of the helicorder as I want to, I then come back to each of the recorded times and zoom in to confirm whether or not it is a potential meteor or not (i.e. N wave form, first cycle biggest, etc and no seismic trigger). The second screenshot below shows what that looks like for a successful detection. Note that there is a small seismic signal that coincides with the N wave in infrasound, but as this signal is small, and there are other seismic signals of similar size and frequency that do not trigger an infrasound signal, there's no reason to believe this one has triggered this N wave.


As we had rain last night, conditions were far from ideal, as rain produces a lot of infrasound. Despite this in 9 hours of data I was able to detect 24 possible candidates and then eliminate 4 that were definitely not meteors, and 14 that are very likely meteors. The remaining 5 might also be meteors as well but the signals were so weak they were hard to separate from the noise.


The sporadic meteor rate is usually 5 to 10 per hour detected visually in ideal conditions. In not ideal conditions with rain falling, the RS&B achieved 1.5 meteors per hour (14 in 9 hours) or about 15 to 30% of ideal visual rate.


This process needs more testing, but I'm encouraged that my RS&B doesn't seem as deaf to meteors as first thought.
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