(meteorobs) re-- Counting the meteors, using a VLF receiver

[Jean-Louis.RAULT at fr.thalesgroup.com]

Hi George

Please find below some answers to your questions.

Kind regards

Jean-louis

> -----Message d'origine-----
> De : meteorobs-bounces at meteorobs.org
> [mailto:meteorobs-bounces at meteorobs.org]De la part de drobnock
> Envoyé : jeudi 13 mars 2008 13:17
> À : meteorobs at meteorobs.org
> Objet : (meteorobs) re-- Counting the meteors, using a VLF receiver
> 
> 
> For
> Jean-Louis F6AGR
> Radio Commission
> International Meteor Organization
> 
> Hi
> Reviewed you information on the Yahoo VLF Group site. Some questions -
> 
> 1. Did you observe the visual magnitude of the meteors recorded by the
> VLF/VHF receivers?

No I didn't. The preliminary records reported on the Yahoo VLF Group site 
were performed on daily sporadic small meteors, which were not visible by eye.
The radio forward scatter system working on 48 MHz is much more sensitive than any visual (or video) system.
The hourly count is up to 3 or 400 meteors/hour each morning.

> 
> 2. Can you, in repeating additional recordings/observations,  
> record the
> signature in an auditory mode? 

Yes for sure. All the raw data are recorded as audio wav files.

> And display the VLF wave form 
> of the VLF
> signature?

Yes I can, but at the moment I can't certify that a VLF signal occuring at the same moment as a meteor is really generated by the meteor. It could be also a coincidence.  I need much more records to perform any comprehensive analysis. And this takes a long time (driving or hiking in remote areas, because recording VLF signals requires very quiet places, radioelectrically speaking)




> 
> 3. Is your next step to record, over a period of time,  both 
> visual and
> VLF/VHF RF captures of meteor activity  in real time?

The next step is to perform VLF/VHF records during major showers, to get a "large" number of meteors.
Visual observation (by eye only) will be performed in parallel.
Before investing in a sophisticated video automatic recording system, I would like first to convince myself that VLF signals are clearly generated by meteors.
Optical detection gives generally some tens of meteors per hour only, the VHF forward scatter is much more sensitive and so I hope to get much more data when comparing VHF/VLF records than comparing visual/VLF data.

> 
> 4. Any explanation why,  over the observation time of meteors with
> radios, why there has been no strong indication of meteors 
> producing RF
> signatures in the upper spectrum of the electromagnetic spectrum --
> example -- receiving a meteor generated RF signature in the 1 
> to 20 MHz
> range?

No idea. I started to experiment on VLF, just because I found a lot of papers/chats/studies (starting with Keay theories) talking about VLF and meteors, with no clear conclusions.
However, it would be a good idea to investigate also on the HF part of the radio spectrum.
So many beautiful girls, so little time ...


Best regards

Jean-Louis