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Graves loss of signal

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Graves loss of signal

First let me state that I am new to meteor observing using the Graves radar signal

The equipment I use is a 3 element Yagi, a Funcube dongle pro plus and Airspy software.

I am based in Shropshire, sited some 140 meters above sea level and the antenna is 6 meters above ground horizontally polarised, mounted with 5 degrees of elevation pointing due south.

On the night of the 12th/13th starting at 23:30 to 00:20 I recorded meteor echo's and have made a video of the same for my local astronomy club.

On the 13th At 19:40 to 20:00 I recorded  24 echo's but from 20:00 TO 20:30 nothing. I switched on the recorder and left it running for 2.5 hours. All I recorded was static.

Next morning I switched back on and recorded echo's and have used the equipment since.

My question is was Graves turned off at 21:00 local time on the 13th?

Thanks

Grant Privett's picture
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Maintenance?

Thats a fun system. I wasnt aware of them.

The GRAVES system may be 24/7 but you can imagine it might go down occasionally for cable maintenance or software updates. 

Saw online a mention of an upgrade in 2015 but nothing more recent.

Also came across an email address for someone in the French Airforce noted as a contact. I doubt if anyone will complain if you ask them. Ignoring you won't cost them anything. :) What do you lose?

• French Air Force - Franck Schrottenloher   spatial.cdaoa@air.defense.gouv.fr

When you are content that its working well, is there any chance you could give a talk on it to the Shropshire Astro Soc? They are always keen to hear what people in the county are up to!

Americo Watkins's picture
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availability of suitable aerials

This is an area I'd like to get involved with and introduce my nephew too and set up a double radio back scatter meteor detection  station for comparison.

I know that the aerial  can be made up, but I haven't the time at the moment.  Can an effective aerial be purchased for radio back scatter detection of meteors or if their might be any members who could make one up for a suitable "donation"?

Thanks,

Eric

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graves update

I have added  a picture of what I see on the screen which I am interpreting as a meteor echo.

The audio gives a "ping" if its a small echo and the larger ones more of a "Pheeeeuuuu" 

stewartw's picture
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Joined: 01/04/2014 - 13:02
GRAVES Offline

Hi All,

Yes, it looks like GRAVES was offline on the night of the Geminids maximum - there were a number of tweets about this from myself and Richard Fleet at the time - see here and here. The twitter posts include some speculation as to whether this was coincidental maintenance or was in fact a deliberate decision on the part of the GRAVES operators.

There are a number of antenna suppliers. For the GRAVES system that members of the NEMETODE team installed at Dunsink Observatory earlier in the year we used a 3 Element Yagi from InnovAntennas. Having said that, making one yourself is very straightforward and can be accomplished in an afternoon - see Paul Hyde's instructions here.

Finally, there is lots of useful information and advice / support on detecting meteors by radio on this forum.

Hope this helps!

Best regards, William

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Graves offline

Thanks.

As its a military installation my guess was that they would not divulge operational details so my best hope was that others monitoring the station would confirm that it was down.

Many thanks for responding

Grant Privett's picture
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Not sure

I thought it was operated by a private company and processed by the military. Pretty difficult to make a high powered radar being turned off a secret, they aint exactly covert :) 

Happy New Year

Americo Watkins's picture
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Antenna

William,

thanks for the info.  I have the same DIY instructions for making the antenna.  Time is really lacking at the moment. The ready constructed source is useful, I'll see if I can get one to match the DIY specs for radio back scatter.

Eric

stewartw's picture
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Antenna & RMOB

If you give the team at InnovAntennas a call and explain the application, they'll tweak the antenna design to match the GRAVES frequency for no extra cost (they didn't charge me extra). There are some additional notes here relating to a supplier of a pre-made cable too.

If you take a look at the RMOB webpage, you'll see that everyone who was monitoring the GRAVES frequency had dropout on the night of the Geminids maximum.