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WorldRecordWIFILink

WorldRecordWIFILink
Melbourne Wirless World Record

Please add you interest, ideas and capabilities below for a MW attempt at a world record wifi link.

TonyLangdon (VK3JED) can provide

AdrianLodders:

MikeCampion (node hkf)

Jamie Moir from Techtopia

HoracePinker

David Smith

CRC

DanFlett

Peter melb_ap

 need a feed & to make a mount , it comes in two halves
 and can easily be transported in a 6x4 trailer.


iViLe


David Nuttall


Shaun (NodeIZA)

Issues that need resolving.


Suggestions for things to do with the link once it's up - for publicity purposes.

Test these things out on the dry run first



Team A (Camels Hump)
Adrian Lodders
Tony Langdon (Preferred site, most convenient, local knowledge)
Peter melb_ap

Team B (Mt Buffalo)
Tony Langdon (Can go here if too many people at Camels Hump and not enough here)
Mike Campion
David Nuttall

Stage 1 local metro equipment testing discussion.
5/8/05 Peter melb_ap Myself and John bigjohn have done some initial testing of a 1.8mtr solid dish to see what comparitive results could be derived on wlan and 2.4gig.
We compared the side by side received signal from node HKR between a hills vagi (which is rated at 16.5Dbi) to the dish using a veritech card and netstumbler.

The feed we used on the dish is a cantenna made from a corinthian tin.
(netstumbler link to follow) The test put the dish at about 15db better than the vagi in netstumbler Making it approximately 31db at 2.4 gig.

Comparitivly with the same cantenna on a 65cm offset dish in previous tests showed about 28-29 db gain.

I dont know if the feed is quite right for the dish, but this was just a rough test that i'd been planning anyway and thought i'd share.

Futher from this I want to see what the real world diversity capabilities are of the veritech card.



Requirements Discussions

Antenna Discussions
- what feed design we could use
- what dish we'd use and where we could source a pair from

Peter melb_ap 17-8-05 - from 12/8/05 mw meeting DN ratbaggy, MC mjc, Peter melb_ap ; regarding the feed, we resolved to start testing commercialy made units
 to attempt to bypass the r&d required to make an effienct unit but this will
 take some time to work out and is vitially important to get right.


Peter melb_ap 17-8-05 - from 12/8/05 mw meeting DN ratbaggy, MC mjc, Peter melb_ap ; for dishes , david mentioned melbourne satellites had a special on 2.5 ish mtr solid dishs for $150 as a possibility (But i think we'll need much bigger for a legal eirp record with diversity)

dna 19-8-05 Thinking about the beamwidth of the transmitting antenna. At the distance we are talking about an antena with a beam width of 7 degrees covers something like 25 Km.
  1. convert degrees to mils (7* 6400 / 360 ) = 124.444
  2. 1 mil subtends 1 metre at 1 Km, so at 200 Km 1 mil subtends 200 metres and 124.444 mils subtends 24.888 Km( 124.444 * 200 / 1000 )

Even with a narrow beamwidth transmitting antenna you are painting a really really big target at that distance. That means the aiming of the transmitting antenna is not so critical, but it also means your available energy is spread out a lot more. I'm thinking you want to have a second transmitting antenna to switch to once you have done the initial allignment that has as narrow a beamwidth as possibe to maximize the energy available at the other end.

Peter melb_ap 17-8-05 Not sure quite how your formula works, whats the 6400 for ? Regarding transmit , yes i agree it's pretty pointless covering a large area. Ideally we need an antenna with a very narrow beam width , but moderate gain , so we can still use enough power to light up the antenna adequately.

This'll probably come down to testing.

dna 20-8-05 I'm converting from degrees into Mils. there are 6400 Mils in a circle, so divide degrees by 360 ( dimensionless) and multiply by 6400 gives the angle in Mils. I'm converting to Mils because it's easy to extrapolate an angle to how long it is on the ground at any distance. 1 Mil is 1 metre at 1000 metres so 124 Mils is 124 metres at 1000 metres and 24800 metres at 200 km.

So, the question is what sort of antenna gived a very narrow beamwidth? I'm thinking it is probably a yagi with lots and lots of elements or maybe even a phased array of such yagis.


Equipment Discussion
- what equipment and methods we could use for initial lineup
- what levels should we start at (ie should we start with
 maximum power & work down to at least allow for a progression
 down to a long diversified link (obviously the hardest to acheive)


Peter melb_ap 17-8-05 - from 12/8/05 mw meeting DN ratbaggy, MC mjc, Peter melb_ap ; as for equipment , an fm carrier on 2.4 Ghz run by a licenced ham was agreed upon by us
 with a spec analyser on the other end as one of the easiest methods.

Also start with high power and wind it down to the minimum to see what margins we have and if we can do it with ism band eirp limits, or if not how much extra gain will be required to make it (is it practical).



Site Suitability Surveys
- what locations for inital trial runs
- how practical are the sites for access - do we have to lug 100kg of equipment up a hill
- time of year - ie the USA tests were done across the desert
 to get the dryest air possible.


Peter melb_ap 17-8-05 - from 12/8/05 mw meeting DN ratbaggy, MC mjc, Peter melb_ap ; Mike did a visit to camels hump at mount macedon and reported that there is a 10 Minute walk to the top with rocky terrain finishing the trip.
Is this correct for this site Tony ?

Mike hkf 18-8-05 Concerns with the lack of open space and access at camels hump site for the size of the equipment we would end up needing. Also lack of LOS at ground level in the mt buffalo direction.











Google Earth KMZ file showing Camels Hump and Mt Buffalo locations
External linkMelbWirelessWiFiRecordAttempt.kmz




Path plot



Version 40 (current) modified Tue, 03 Jul 2007 23:12:23 +1000
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