(meteorobs) Negative HF radio meteor reception

[James Beauchamp]

>From an emission perspective, I don;t think you're going to get much.
 
Laws of physics say there would be some, and there have been some studies on electron plasma emission  
 
(http://dspace.mit.edu/bitstream/handle/1721.1/55701/RLE_QPR_088_XXIV.pdf?sequence=1)
 
Another possibility would be synchotron emission.  How do meteors act in the thin atmosphere in terrestrial magnetic fields?
 
I don't think the field strength of such emissions will approach that of normal RF scatter.
 
Interesting, though..
 
http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=5104181
 


--- On Fri, 3/2/12, Thomas Ashcraft <ashcraft at heliotown.com> wrote:


From: Thomas Ashcraft <ashcraft at heliotown.com>
Subject: Re: (meteorobs) Negative HF radio meteor reception
To: "Meteor science and meteor observing" <meteorobs at meteorobs.org>
Date: Friday, March 2, 2012, 2:00 PM



Hi Sam and James,

Thanks for your replies.

Actually, I should have been more specific in my presentation.  I was actually looking for direct high frequency electromagnetic emission that might originate from the meteor itself  rather than reflected transmitter scatter in this case. 

I am getting ready to start another long term direct emission monitoring project at VLF and hopefully ELF wavelengths and so am thinking possible direct emissions these days.

By the way, that youtube video link is very good information.

Thanks and clear skies,
Thomas



On 3/2/12 11:48 AM, Sam Barricklow wrote: 
Thomas, 


Due to the lower frequency, the doppler shift is considerably less at HF frequencies than at VHF.  Also, to hear a meteor radio echo that is not "polluted" by either ground wave or sky wave, your receiver must be within the "skip zone" and beyond ground wave distance.  The skip zone is where the skywave is passing above your location on its way to or from the refraction zone in the ionosphere, and before the signal returns to the Earth's surface.  


The ideal signal source for HF meteor radio echo work would be a shortwave broadcast station that is located over the horizon, too far away for you to hear groundwave and too close for ionospheric propagation to occur.  


Here's a link to a YouTube video on the subject:


http://www.youtube.com/watch?v=xgrxQdRrCRE


A limited amount of information is available at the following website:


http://sci2.esa.int/leonids/leonids99/leolisten.html


WWV in Fort Collins might be useful for you when the MUF (maximum usable frequency) is lower than or near the receive frequency, especially for the 15 and 20 MHz frequencies.  WWV transmits at 2.5, 5, 10, 15 and 20 MHz.


Other propagation modes might produce "interference" even when no direct ionospheric or groundwave propagation exists, such as backscatter or even forward scatter, both of which are mostly produced by the ionosphere.  Backscatter from distant mountains or ocean waves may also provide signal reflection / refraction at times.  Tropospheric ducting might occasionally allow propagation, but it is more common at VHF and above.


Note that refraction produced by meteor trail ionization will normally last longer on HF than on VHF. 


Sam Barricklow



On Mar 2, 2012, at 11:54 AM, Thomas Ashcraft wrote:


I am not aware of any HF radio ( high frequency or decametric  ) direct 
emission monitoring of meteors or papers on the subject.



 
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