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wxsatuser

Meteorscatter using GRAVES

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This is my first foray into receiving meteors, satellites and direct signals from GRAVES.

Many years a go I did a lot meteorscatter on 144MHz and have just got my hamradio station back on the air.

Setup is an ICOM IC 7100 transceiver feeding a Create 25element log periodic at 12metres above ground, 16metres ASL.
Location is not ideal for VHF but on 144MHz I have worked over 300 locator squares on various modes.

Anyway last night fired everything up and using Spectran had a go at GRAVES.
Received GRAVES direct with lots of QSB plus ISS and another unidentified sat plus lots of pings and the odd longer burst.
Here are the screen grabs, signals on the whole quite weak but direct was audible with a S1 meter reading at times.

First two show ISS around 19:36 plus direct with the odd ping.

graves-iss.jpg.b0acdfaf53dad97c625f0570bd9b0aed.jpg

graves-iss1.jpg.fe11c7c91de2f8cdd78884fcf16b21de.jpg

UFO
graves-sat.jpg.85fea9197a7f6ebac948cb29067077fc.jpg

Meteor.
graves-meteor.jpg.97a937cb0bc311bf9bedd4132f50ac68.jpg

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Looks good wxsatuser.  I used to run 144MHz MS and EME 20 or 30 years ago years ago, but family came along and I had other priorities.

With an antenna that size and gain located in West Sussex, you'll likely hear the direct signal which will make the weaker meteoric reflections less easy to differentiate.  If I interpret your traces correctly, they do indeed show the groundwave as well as some scatter signals.  The beamwidth will be quite small as well, so the area of the sky that you're covering will be smaller than perhaps is ideal. 

I'm not familiar with the program you're using.  Quite a few people here use Spectrum Lab fed from an audio source.  Spectrum Lab has a scripting language available to it which allows the program to be automated, logging meteor detection and writing wav and jpg data to file.  You're lucky to have the Icom 7100: that's a nice piece of kit.  I use a simple Software Defined Radio running from a HB9CV mounted on the side of the house at about 3 to 4m.  Far from ideal for weak signal work, but it's proving quite effective detecting meteor scatter from GRAVES.  If you have the opportunity to use a lower gain antenna, you may be pleasantly surprised.

Richard

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Just goes to show a modest station can do quite nicely seeing what you are receiving. :icon_salut:

For the moment I will carry on with the log periodic as I want to mess about on 50, 70 and 144megs as well.
The 7100 is a nice radio been messing about on 20metres with WSJT-X  FT8, interesting where the signals reach
with 25watts and a quarter wave GP. ?

The GRAVES tropo signal is there but comes and goes at best it moves the smeter to S1, I can still hear it with no movement
on the meter and the program picks it out when not audible.
Was pleased to get two satellites on the first try, first ISS and the other I have not identified yet.

I'm in the process of getting Spectrum Lab going, hopefully this weekend.

Mike G1HWY

 

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At 50MHz, meteor reflections should be stronger, if all other parameters are the same, as you'll know about from amateur radio Mike.  I think BRAMS is the go to source at that frequency.  I assume it's operational, but have no aerial to cover that band to confirm.  Even so, it may be too close to you to be useful.

Perhaps a 6m beacon in Southern Europe may be a good source?

Spectrum Lab is a bit obscure at first when trying to get to grips with it, but is very capable.

Good hunting,

Richard

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On 05/10/2018 at 20:18, BiggarDigger said:

Spectrum Lab is a bit obscure

Master of understatement ?

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Setting up Spectrum Lab this afternoon as well as lots of pings had this near 6 seconds burst.

Not sure what to make of the pattern, any guesses?

capture_133_07102018_162946.jpg.31f0ed3a05bb8c2aa2e222bd8e8348d1.jpg

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I think you've got several things in play here, most of which are good.

There appears to be groundwave signals being received before and after the strike.

There's a significant hook from the head reflection almost buried under the 16:29:35 time line (which is a good indication that it's a meteor rather than aircraft or some other object).

There are horizontal spikes appearing above and below the centre frequency during the decay of the plasma tail.  I believe these are caused by the FFT algorithm aliasing when the GRAVES radar switches antenna array causing a step change in the received signal strength.

There is a "double trace" occurring during the decay of the tail.  I see this a lot on my long burst detection, but I'm unsure of the mechanism.  I've read that GRAVES is running a single carrier waver, and your groundwave detection appears to confirm this: so I don't know if the "double trace" is an FFT alias (unlikely I would have thought as it doesn't occur all the time on my detections) or if it's some other reflection mechanism.  I typically see this "double trace" when the tail reflection is "noisy".   I don't recognise it from my amateur radio meteor scatter operation in the past and I don't know what is represents.

Overall, I've seen all the artefacts you have in this trace from here in Scotland with the exception of groundwave and agree with Neil.  It looks a good solid detection.

I've recorded a few bursts today and saw a lovely visual Draconid meteor last night while out with the scope, but didn't record this one at 16:29.  However, my geometries will be very different to yours.

Richard

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