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BiggarDigger

Meteor detection: path from Scotland to GRAVES

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1 minute ago, The Admiral said:

So far as the condition of 'specular reflection' is concerned, I believe I'm right in that it only relates to the static column of ionisation and not to the meteor head?  I can't remember what I've read and what I haven't now :icon_scratch:. Brain like a blancmange!

It was specifically covered in the paper above in the context of head echoes. I can't see why it wouldn't be a factor in the static reflections, but they are considerably more complex to model due to Fresnel zones /  constructive/destructive interference, under/over dense regimes, etc.

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We need a learned conference to discuss this topic.

First identify a suitable pub confernce centre.

Second find someone to sponsor the beer debate.

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40 minutes ago, IanL said:

It was specifically covered in the paper above in the context of head echoes. I can't see why it wouldn't be a factor in the static reflections, but they are considerably more complex to model due to Fresnel zones /  constructive/destructive interference, under/over dense regimes, etc.

Thanks Ian. I did skim through that paper when it was first linked, but I'll need to re-read I think!

Ha! I had printed it out too. Cor, what a memory :ohmy:

Ian

Edited by The Admiral

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I can't see me getting my head around this without a session of handwaving and a whiteboard, I'm afraid.

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22 minutes ago, Stub Mandrel said:

I can't see me getting my head around this without a session of handwaving and a whiteboard, I'm afraid.

In fact your idea of a pub and beer might resolve everything ? well at least for me.

Cheers,
Steve

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So, what have we established?

1. There appear to be non-trivial rear facing lobes radiated from the GRAVES radar site.

2. These rear facing lobes contain suffient energy to produce forward meteor scatter signals detectable far beyond the northern horizon of the backscatter signals generated by the main "southerly pointing" lobes, even with a modest setup.

3. The topic and understanding of both the mechanics and physics of meteoric reflections of radio signals is complex.

4. The data we have to hand is only partially complete.

5. Neil wants a beer.

 

I'm off to read that article...and maybe have a beer too.

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2 minutes ago, BiggarDigger said:

I'm off to read that article...and maybe have a beer too.

A few of things about that article.

  1. I'm having a bit of a problem understanding their Fig 2. I'm wondering if they've mis-labelled it.
  2. I'm not happy that they seem to account for the Tx-meteor Doppler shift by plugging in to the co-located Tx/Rx equation, i.e. just doubling the shift.
  3. Interesting that the head echoes last significant fractions of a second, much longer than ours. I wonder if this is because they are using 50MHz rather than 144MHz? Anyone tried using the BRAMS transmitter?

Beer and mathematical equations don't mix, I find ;<).

Ian

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