Activity weekend 2/3rd October 2021

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radiogareth
Posts: 1215
Joined: Wed Jan 06, 2016 9:46 am

Re: Activity weekend 2/3rd October 2021

Post by radiogareth » Mon Oct 04, 2021 2:14 pm

Plenty of 'sooo near, yet so far' contacts (well, near contacts) on Sunday. Bit of occasional help from passing aircraft (and some fascinating doppler/multi-pathing going on) checked out via the very handy 'airscout' software. As Steve commented, a lot of 'flutter' observed, just not long enough for a lock.
The wind got up in the afternoon so I had to lower the pump-up mast as its un-guyed (garden too narrow for effective guys).
Martin G4FKK and I tried again on 70cms, with over 50 watts each end and decent beams, but the gravel lump between us prevented even a slight lock. What's so strange is that we can operate on 4 & 2 with just 1/2 a watt on the same path and with lesser beams.
Onward to the next event in November :-)
Gareth

G4HTZ
Posts: 217
Joined: Sat Aug 02, 2014 4:21 pm

Re: Activity weekend 2/3rd October 2021

Post by G4HTZ » Mon Oct 04, 2021 4:26 pm

radiogareth wrote:
Tue Sep 28, 2021 6:41 pm
Thanks, that's just what I needed, being able to estimate the terrain in very helpful and finding myself exactly on the map great too. JO01AI09KQ now :-)
Rob, looking at the path between us there isn't much in the way except a 'bit of curvature'. Hoping to have 70cms, 23 and 13 ready to point in your direction.
Gareth
Possible path to east Essex Gareth ??


https://k7fry.com/grid/?qth=JO01JN60&from=Jo01jn60&t=h
Steve G4HTZ

ASHEN nr Sudbury JO02GB52 90m ASL

70cms DATV portsdown 4 + RYDE rx …14 or 18 ele yagi …LNA …hopefully 100w amp at some point

radiogareth
Posts: 1215
Joined: Wed Jan 06, 2016 9:46 am

Re: Activity weekend 2/3rd October 2021

Post by radiogareth » Mon Oct 04, 2021 4:56 pm

Hi Steve, yes, looks like it might fly. I can put up 70 cms pretty quick (so long as there's negligible wind!) and give it a go anytime (ideally in daylight so I can see what I'm doing with the mast....
Not tomorrow morning though....
Gareth

g8gtz
Posts: 1733
Joined: Wed Apr 07, 2010 6:26 pm

Re: Activity weekend 2/3rd October 2021

Post by g8gtz » Mon Oct 04, 2021 5:16 pm

Interesting sessions on both Saturday and Sunday playing with aircraft bounce on 70cms. I used Airscout to see what planes were flying in the path and it was amazing to see the signals come up from nowhere on the Portsdown bandviewer when a plane flew over.

http://www.airscout.eu/

I managed to snatch a decode of Gareth G4XAT over a totally obstructed path.

No joy decoding Rob on the North Yorks Moors but did see his signals on the band viewer when a 777 flew over the mid point near Nottingham

But the real success was receiving Arthur G4CPE over an obstructed 90kms path - there was no signal until a plane flew over the midpoint at High Wycombe.
CPE GTZ 5 (Small).JPG
CPE GTZ 5 (Small).JPG (74.65 KiB) Viewed 4471 times

I posted a video on Twitter here https://twitter.com/G8GTZ/status/1445070841629351948

This shows the amazing frequency selective flutter - not surprisingly the decode was intermittent - the Portsdown rxr in no scan mode managed several locks up to an MER of 6dB at one point but MiniTiouner did not manage any decodes.

Obviously, a lot more experimentation needs doing to see what potential this mode has for DATV (NB ops have been doing it for years) - I suspect 23cms would be better as the shorter wavelength will reflect more off smaller planes and would OFDM work better than DVB-S due to the frequency selective fading and phase changes?

73

Noel

arthur21
Posts: 53
Joined: Fri Sep 02, 2016 9:04 am

Re: Activity weekend 2/3rd October 2021

Post by arthur21 » Tue Oct 05, 2021 1:21 pm

Hi Noel
I have just watched your video of the amazing signal flutter over the very obstructed 90km path between our 2 sites.
After the contact I discovered my RX preamp down the garden was not powered because of a broken cable, it may have been possible to have had a
2 way contact.
We should try DVBT next time it should perform better with the phase changes and flutter.
73 Arthur G4CPE

radiogareth
Posts: 1215
Joined: Wed Jan 06, 2016 9:46 am

Re: Activity weekend 2/3rd October 2021

Post by radiogareth » Wed Oct 06, 2021 10:42 am

The flutter was fascinating - as I tried to receive G4CPE I had the odd lock indication and then suddenly I saw a MER of 11 and got the headers etc, but not long enough for any video. Attached shows the grab I did manage though. So near yet so far.....next time...
Gareth.
G4CPE_via_Flutter.jpg
G4CPE_via_Flutter.jpg (140.9 KiB) Viewed 4310 times

M0DTS
Posts: 653
Joined: Sun Feb 24, 2008 9:03 pm

Re: Activity weekend 2/3rd October 2021

Post by M0DTS » Thu Oct 07, 2021 8:42 am

Well, if anyone wants to try some real aircraft scatter DX I'll put 2x 25el yagi back up at home in prep for next month.
That's ~21dBi gain and i can probably run ~100w to them so a good 10kW EIRP.

My best direction to hit any planes is SSW from IO94IL, unfortunately i'm blocked by hills directly south all the way round to east.

Any takers?
Rob

radiogareth
Posts: 1215
Joined: Wed Jan 06, 2016 9:46 am

Re: Activity weekend 2/3rd October 2021

Post by radiogareth » Thu Oct 07, 2021 9:52 am

Does the bounce have to be in a straight line I wonder.....since I'm 348 degrees to you :-(

Gareth

G4NZV
Posts: 33
Joined: Wed Mar 24, 2021 8:35 pm

Re: Activity weekend 2/3rd October 2021

Post by G4NZV » Thu Oct 07, 2021 10:14 am

Hi Rob,

I am located in IO82WA which is 281Km on a heading of 192Deg from your QTH. Will this miss your local hill?

Kit here on 146.5MHz 50WERP 9 ele Horizontal yagi TX and RX on DVBS/S2/T especially interested in trying DVBT and comparing with S/S2.

Receive only on 437MHz 19ele yagi Horizontal DVBS/S2/T.

Available most of the time to give this a try.

OR anybody else........

73 Steve G4NZV

M0DTS
Posts: 653
Joined: Sun Feb 24, 2008 9:03 pm

Re: Activity weekend 2/3rd October 2021

Post by M0DTS » Thu Oct 07, 2021 12:01 pm

Yeah a bit far round for you Gareth but fine in your direction Steve.
185 to 230deg is my clear view to the south west.
I'm busy today but I'll try get the 70cm yagi's up tomorrow.

I have 2m 8el yagi here but the high local noise and lack of PA at home will limit me on there, 70cm has much more potential.
I also have QRO on 23cm too with ~150W DATV to 3m dish.

Rob

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