ATV on 6cms - It's Cheap and Easy on 5665MHz

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M0DTS
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Re: ATV on 6cms - It's Cheap and Easy on 5665MHz

Post by M0DTS » Sun Aug 27, 2017 10:18 pm

Excellent work on the long path!
The 137km path worked would (i think) break the UK record for lightwaves/Optical comms if attempted....
What are the exact locations? someone maybe interested down that way.

Not sure this will be of wide interest but tonight i've measured my 6cm Analogue receivers for sensitivity...

The openpilot RX5808 'diversity' receiver could manage an identifiable picture at -103dBm input, same for both of it's inputs.
My old Nikkai video sender receiver was slightly better, managing the same quality signal at -104dBm input.

Useful figure for plumbing into radiomobile for testing marginal paths ;-)

The Nikkai receiver had an LNA between the back of it's small patch antenna and the receiver can, i disconnected the patch and fed the signal source directly into the LNA, results were just the same as without the LNA! It must be to overcome the short piece of lossy cable connecting the two.

Rob

g8gtz
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Re: ATV on 6cms - It's Cheap and Easy on 5665MHz

Post by g8gtz » Mon Aug 28, 2017 7:51 am

Hi Rob - I see from your post on Twitter that the 10 GHz contest seemed to have turned in to an impromptu ATV activity day!

Yes - it's a great path right up the Bristol Channel, I'm pretty sure it would go further if we could find a site and get people to travel to it from the Midlands - I'm not sure we can go much further, Dave's travel time was 2 hours and it took me 3+ hours to get home last night.

The locations, Dunkery Beacon and Cleeve Common, are correct on the site map https://www.google.com/maps/d/u/0/edit? ... 945663&z=9

I'm sure we would have worked on 10 GHz but my transverter took exception to 500+ miles rattling around in the back of the Land Rover - it was surprising that I worked Dave on DATV but great pictures from the Portsdown as usual and no hat! And we had 23dB MER at 2Ms (2+ MHz) so plenty of margin left but optical would not have gone yesterday - very misty...
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73
Noel - G8GTZ

M0DTS
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Re: ATV on 6cms - It's Cheap and Easy on 5665MHz

Post by M0DTS » Mon Aug 28, 2017 8:59 am

The kit does give in eventually, surprised some of mine has not failed yet for the same reason!
An hour's travel in the van with whistling antennas on the roof is enough for me.

I have been playing 6cm NB, just Rx only at present but i can hear the GB3ZME and GB3OHM beacons well from home >220km so i have some dx possibilities on ATV that way.
I also now have my 5665 Tx boxed up with the 8W amp ready for some Dx :-)

Optical paths require short notice action and some ground work to get a feel for visibility but great when it works.
Still hope to get back to Optical ATV soon.... 11km ODX so far on there.

Attached is the brief decode from Tony on 2m DATV Yesterday, he was getting lock on me but not long enough to decode, probably due to aircraft scatter.

Rob
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g8gtz
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Re: ATV on 6cms - It's Cheap and Easy on 5665MHz

Post by g8gtz » Tue Sep 05, 2017 4:38 pm

I went out to the Ridgeway near Didcot (IO91IN) today to do some 5.6GHz tests with G4CPE, M0SKM and G0WFT on Dunstable Downs (IO91RU). It's 64Km path along the Chilterns with one serious bump near Dunstable in the way.

G4CPE and M0SKM were running barefoot 600 milliwatts tx in to 45cm dishes and to start with I could just about see them at P1 - the dish at my end was about 7ft off the ground with absolutely clear take off. I then transmitted using a 2watt PA and got a P4 report.

I then had the radical idea to raise the mast by about 3ft! By doing this their pictures came up to a P3+ with colour. However, when I continued to raise the mast the signal dropped out completely and then came back up when at a total height of 13ft. Video of the effect posted on Twitter at https://twitter.com/G8GTZ/status/905118091679604737

We tried the same experiment with me transmitting and the same effect was noticed - and then it started to rain hard in Dunstable and we had to abandon the tests but presume we were seeing some refraction across the obstruction near Dunstable.
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A very interesting morning and proved yet again the FPV units are excellent value for money - it will be good to see some more 5.6GHz activity during the activity weekend in 2 weeks time.

Noel - G8GTZ

M0SKM
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Re: ATV on 6cms - It's Cheap and Easy on 5665MHz

Post by M0SKM » Tue Sep 05, 2017 5:14 pm

Many thanks Noel; an interesting but damp morning.

While raising and lowering the dish on my tripod I observed similar changes in signal level.

These are two good sites for a first test; we will (weather permitting) be on the downs during the activity weekend Sunday 17th.

Send a pm if you plan to be out and want a contact.

Steve

g8gtz
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Re: ATV on 6cms - It's Cheap and Easy on 5665MHz

Post by g8gtz » Tue Sep 05, 2017 5:23 pm

I just updated my post with a link to the video I posted on Twitter.

I've not decided where to go in 2 weeks time yet (might even go to Clee Hill) but will post my plans on the forum.

Noel

g8gtz
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Re: ATV on 6cms - It's Cheap and Easy on 5665MHz

Post by g8gtz » Mon Sep 18, 2017 8:23 pm

I've just updated the wiki with the latest 5.6GHz information including an updated known stations on the band list - https://wiki.batc.tv/5.6_GHz
73 - Noel - G8GTZ

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G1LPS Terry
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Re: ATV on 6cms - It's Cheap and Easy on 5665MHz

Post by G1LPS Terry » Mon Oct 09, 2017 9:44 am

http://www.ebay.co.uk/itm/Wireless-2000 ... 2749.l2649

Couldn't resist an other 2w 5665mhz TX AT ONLY £17
I can confirm it does 5665mhz on channel 3
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g4pdf
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Re: ATV on 6cms - It's Cheap and Easy on 5665MHz

Post by g4pdf » Tue Oct 17, 2017 3:07 pm

Hi everyone,
(My first posting as a Newbie to the Forum, not to BATC though)
Recent illness has kept me away from the Newark Rally and local activities, but I have used my recovery time to watch the UK microwave group (RSGB Convention) and CAT17 presentation videos. These have spurred me on do something relating to ATV.
In the next couple of weeks I'm hoping to put together a bare-bones Tarot system and with that in mind I'm interested to know if there are any of the Hypergain HG5727G aerials, or similar, for 6cms still available please?

If you want to discuss off the Forum please email me: g4pdf<at>bobcopeland<dot>net

Thanks and 73, Bob - G4PDF
73 - Bob

arthur21
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Re: ATV on 6cms - It's Cheap and Easy on 5665MHz

Post by arthur21 » Tue Oct 17, 2017 4:20 pm

GB3TZ has now got an experimental I/P on 5665MHz with horizontal polarization. The aerial is a 12dbi Omni but at the moment it is very close to the tower. We hope to improve the position of the aerial soon. Two stations have so have far managed to get P3 pics in ( G4CPE and G6OUA )
It will be no surprise for some viewers to know that only the video is being relayed but we do intend to get the audio ( 6.5MHz ) connected in the future. If you are out portable with 5GHz at the activity weekend please give it a try, the aerial should be fairly good to the west. 73 Arthur G4CPE

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