(meteorobs) "Julian Portik" VLF

Julian Portik webmaster at julian-portik.de
Thu Aug 13 08:56:23 EDT 2009


Hello,

last night we observed again in another direction. We saw more than 40 
Meteors in 3 hours.
Unfortunately I hadn't got much time to tune the antenna to 3 KHz and I 
found nothing to
pull up the antenna above one metre :-(.
But this night, there were some "maybe's". At least we've got some progress.
Next we'll observe the Orionids so I've got much time to improove our setup.
Do you think our receving circuit itsself is one problem, too (I thought an 
OP-AMP is the best
solution because of it's high-impedance input)? Would you suggest that a 
frame antenna is
good to receive meteors?
Did you ever receive meteor related signals with your setup? If yes could 
you send me some example sound?

Thank you very much!

Many greetings

Julian Portik



----- Original Message ----- 
From: "drobnock" <drobnock at penn.com>
To: <meteorobs at meteorobs.org>
Sent: Wednesday, August 12, 2009 7:44 PM
Subject: (meteorobs) "Julian Portik" VLF


> Subject: (meteorobs) Perseids VLF observations
>
> 1. For a field set up -  the loop antenna needs to be at right angles to
>
>> the ground with the broad side of the antenna (flat end of square)
>> toward the direction of the rising radiant of the shower. You may want
>
>> to "tune" your receiving circuit to narrow the frequency range, and
> not
>> be open to multiple signal sources.
>
>>>So do you think it's a good idea to tune the antenna to approx 10 KHz
> or
> what frequency would you suggest?
>
> My suggestion is to stay below 10 kHz. My receiver - because it is not
> designed with filters and multiple stages -- is tuned for about 3.2KHz
> with a harmonic 9.6 KHZ. The establishing of its resonance was
> accomplished by using a signal generator injecting a carrier and tone
> into the antenna input with the antenna and  fixed capacitor in place
> and with a volt meter at the out put indicating the strongest reading as
> the signal generator was tuned over various frequency ranges..
>
>> 7. For now,  until shown other wise, the signature of a meteor and
>> lightning are similar.
>
>>>The receiving circuit is able to receive lightening as I saw last last
> week
> (it was clearly in the spectrogram and in the sound file)
> Is there anything to compare with the signal strength of meteors to test
> the
> circuit when there's no meteor shower?
>
> I have no way of knowing how to answer this question. The strength of
> the meteors signal is dependent on many factors -- ionization intensity
> of the atmosphere, distance the meteor is from the observer, height of
> the meteor above the observer and more relate to the propagation of an
> electromagnetic wave through space. Even the position of the meteor to
> the observer may be a factor in the meteors output signature..
>
> You can establish a base line for your receivers output for a quiet sky.
> But with other factors present, distant storms, electrical interference,
> and related local noise, solar activity -- there is no established
> method - to date - of measuring a meteors self generated signature,
> based on its mass or visual magnitude of a meteor.
>
> If you can you may want to review a publication called "Meteors and
> Meteorites" By Martin Beech (2006). He has some calculations to help
> work out the relative electrical energy that a meteor may generate.(
> pages 16 to 25) and review his bibliography. This may be useful.
>
> Good luck
>
> George John Drobnock
>
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