(meteorobs) Anyone doing infrasound monitoring?

[Jim Wooddell]

Several people have asked me about the ability to just record audio with an
external microphone using WinSentinel.  I'd do something at my camera.  The
feature seems to be there under the  Video features but greyed out.

I would think with the Chelyabinsk event in Russia, there would be great
interest in this sort of thing.

Jim




On Tue, Apr 9, 2013 at 3:25 PM, Pat Branch <pat_branch at yahoo.com> wrote:

> Most meteors do not produce a large pressure wave that reaches the ground.
> But a number will produce one even if it is not audible to people under
> the path within a radius of a few hundred km.
>
> I have tried asking the Infrasound monitoring stations for data to
> specific events with no response.
> I do regularly pull microbarometer data from the US Array though and they
> are a good source of helping triangulate events, although by themselves
> they are only accurate to a few kms at best. I typically see >2 Pa at
> distances of 200 km for reported sonic booms, 0.2-0.8 Pa out to about 80 km
> for bright fireballs without sonic booms reported. I wish every allsky
> camera also recorded pressure.
>
> It is not very hard to build an array that can give direction to an event,
> but it is expensive and you need two arrays to triangulate an event.
> We have the advantage of having an accurate timestamp from cameras or
> radar echos which can give you distance also. It is probably easier to use
> two separated single sensors with a timestamp than building multiple arrays.
>
> But if you want to build an array you simply need at least 3
> microbarometers (or very sensitive low pressure low frequency sensors) but
> 8 would be better. Unfortunately sensors such as Validyne DP103 cost about
> $800 each. Add that to a signal conditioner/converter such as their USB2250
> at $2250 and it can cost over $10,000 for a station. You also need to write
> some scripts or macros or software which does the data analysis for you.
> The equations are pretty simple, but getting the data into an analysis
> application like Matlab or Excel might not be. Knowing the time of an event
> within a second or so and just having the time of arrival at two points and
> the temperature gradient with altitude you can get the location as a
> function of altitude. With a 3rd point you can determine altitude. So if I
> was going to buy enough microbarometers for an array I would space them out
> 50 kms instead of using the directional angle given by an array setup.
>
> You could probably make a sensitive sensor out of cheap piezoelectric
> sensors and some old drums and get the same performance. If all you want is
> time of arrival. But the size of the pressure wave and distance also gives
> us size of the meteor (as a function of speed). The spikes in the pressure
> wave can tell us the number of particles and spacing of them...but unless
> there are a number of large meteorites in the fall the smaller ones get
> lost in the noise.
>
>
>   ------------------------------
> *From:* Thomas Ashcraft <ashcraft at heliotown.com>
> *To:* Meteor science and meteor observing <meteorobs at meteorobs.org>
> *Sent:* Tuesday, April 9, 2013 12:47 PM
> *Subject:* (meteorobs) Anyone doing infrasound monitoring?
>
> I have started 24 hour continuous all-sky camera video monitoring for
> fireballs in conjunction with my forward scatter radio array.  I
> monitored for daylight fireballs some years ago and would check my video
> at times of strong radio fireball receptions but discontinued that
> regimen as I was never able to discern a daylight fireball in the midst
> of sunlight. I did spend some hours at it.
>
> Also, by some quirk of radio meteor observing there can be a tendency of
> certain low velocity, deep penetrating fireballs that some do not
> register strongly on radio spectrographs.  In any case I am back to
> recording all day and checking the video at times of fireball hits.
>
> But, over the course of the year I occasionally hear sonic booms during
> the day and wonder if some of the booms might be fireball generated. ??
>   This then makes me wonder about infrasound monitoring in conjunction
> with video/radio.
>
> Does anyone do infrasound meteor monitoring?  Can a research-grade
> infrasound system be manifested for little money?
>
> Thanks in advance for any info.
>
> Thomas Ashcraft  -  Heliotown  -  New Mexico
>
> .
> _______________________________________________
> meteorobs mailing list
> meteorobs at meteorobs.org
> http://lists.meteorobs.org/mailman/listinfo/meteorobs
>
>
>
> _______________________________________________
> meteorobs mailing list
> meteorobs at meteorobs.org
> http://lists.meteorobs.org/mailman/listinfo/meteorobs
>
>


-- 
Jim Wooddell
jimwooddell at gmail.com
928-247-2675
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.meteorobs.org/pipermail/meteorobs/attachments/20130409/f7855993/attachment-0001.html