(meteorobs) Negative HF radio meteor reception

[Thomas Ashcraft]

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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