Long range (47-55 KM) point-to-point Wi-Fi link (depending on the chosen site)

[Halcyon]

where specifically would these be, could you put them on the wall or roof of a building, or even bolted to a tree??

They will be attached to buildings. Trees are no good as the slightest bit of wind would throw the beam out of alignment.

[cdev]

This is the New Zealand man's web page about using woks for long distance wifi links. This is from a decade ago, his web page is no longer online.

https://web.archive.org/web/20081002032952/http://www.usbwifi.orconhosting.net.nz/

An example of the surprising successes people had.

https://archive.li/G9Vm

$10 wok keeps TV station on air

[vk2amv]

It's a pity you are doing this project now and now in 3 months time.

I am decomissioning a 21KM Point-To-Point Wi-Fi link in January that has been up and running since October 2012.
It has been up an running from the edge of Parkes, out to the in-law's place in Gunningbland providing them with internet with pretty much 100% reliability aside from one hardware failure in that time.
The in-laws are selling up and moving out of their place in January so the link will be pulled down then.

It is using Ubiquiti Rocket M5's (802.11N Gear) with 30dBi Ubiquiti dish's (They are 65CM in diameter).

I normally run it with conservative settings, choosing pure link stability over speeds because it is only terminating to an ADSL connection in town, but on testing it has done a reliable 240Megabits link speed.
Was quite cool sending data at that speed over the 21KM wireless link when I set it up back in 2012.

If you were doing your project after the time I am decomissioning this link I would have been happy to loan you the Ubiquiti gear to have a play with so you don't have to be out of pocket to do testing.

Hell I would have come down your way and given you a hand as it would be a fun project doing a long haul link from the Blue Mountains. (I think that is where you said you were doing one end of the link from)

It can be a hell of a lot of fun.
Or annoying at times as in my case for the 21KM link I had a 50KM drive by road from end to end, so when I am trying to diagnose a problem and need to drive between sites back and forth, it sucks.

Oh well.
I have not had a look at your path maps yet, I miscalculated and my internet is shaped until Sunday night, but I will have a look on Monday or Tuesday and post back some thoughts.

Anyway best of luck with the project.

[Halcyon]

It's a pity you are doing this project now and now in 3 months time.

Nothing's really preventing us from waiting other than the desire to have a play sooner rather than later.

I am decomissioning a 21KM Point-To-Point Wi-Fi link in January that has been up and running since October 2012.
It has been up an running from the edge of Parkes, out to the in-law's place in Gunningbland providing them with internet with pretty much 100% reliability aside from one hardware failure in that time.
The in-laws are selling up and moving out of their place in January so the link will be pulled down then.

It is using Ubiquiti Rocket M5's (802.11N Gear) with 30dBi Ubiquiti dish's (They are 65CM in diameter).

I normally run it with conservative settings, choosing pure link stability over speeds because it is only terminating to an ADSL connection in town, but on testing it has done a reliable 240Megabits link speed.
Was quite cool sending data at that speed over the 21KM wireless link when I set it up back in 2012.

Yeah I bet! It's still cool in 2017. For consumers to have affordable access to this kind of gear was unheard of 10 years ago.

How did you go with aligning each end? I'd imagine where it was is quite flat so no obstacles to overcome?

Hell I would have come down your way and given you a hand as it would be a fun project doing a long haul link from the Blue Mountains. (I think that is where you said you were doing one end of the link from)

It can be a hell of a lot of fun.

Yep. Without giving too much detail away, one station will be up in the Blue Mountains (more or less along the ridge line facing east) and the other station is down in the South/South-West of Sydney.

If we can get this to work, the idea later down the track would be to extend the network into more of a mesh between friends and colleagues. Why? Because we're a bunch of nerds and we can. :-)

[IanB]

One thought I have about trees, and the impossibility of trimming them, is that trees grow. Treetops that are only slightly impinging this year could grow much further into the sight line with each following year.

[Halcyon]

One thought I have about trees, and the impossibility of trimming them, is that trees grow. Treetops that are only slightly impinging this year could grow much further into the sight line with each following year.

I did think about that. Most of the trees here are fully grown so they shouldn't get much larger. The occasional storm and strong winds generally take care of branches that tend to get too big.

[vk2amv]

Nothing's really preventing us from waiting other than the desire to have a play sooner rather than later.

Well if you can wait until January when I decomission this 21KM link and pull the gear down, the offer of a free loan of this gear is there and genuine.
I honestly don't have any future plans for the gear at this stage, so I am happy to let you have a play with it.

I am also happy to give you help for a weekend to try and get a link up and running and offer my experiance. (My 21KM link is not the only point-to-point link I have done, just the longest in a large number of links I have setup)
I would enjoy the project of trying for a 55KM link for a bit of fun.

Feel free to send me a private message and I will give you my direct email if you want.

If we can get this to work, the idea later down the track would be to extend the network into more of a mesh between friends and colleagues. Why? Because we're a bunch of nerds and we can. :-)

And you need no other reason than that.
It can be a hell of a lot of fun, and is well worth playing with.

[cdev]

In my experience trees need constant attention. They're always growing bigger,so if you don't want them where they're growing you have to trim them back. When they die, you have to remove them or they may fall down on somebody. Trees require maintenance. There is no way around it. So budget for it, or face the fact that you'll have to cut them down and be done with it. (which sucks because lets face it, trees are often beautiful and being alive they arguably have life and interests on some level. Cutting down a tree is killing a living thing. It never feels good. Animals live in trees. And so on.

If you can do it, figure out if your project might not need to cut down trees. Maybe find a path that does not impinge on trees using a very bright light like a laser.. Perhaps - get a much much better antenna or something, if you can push your signal through, go for it, but if trees are in the line of sight, you may want to try to find a better pair of locations. Is there any way you could set up a laser or very very bright LED and visually evaluate the path to see if the trees are blocking the line of sight. Surveying done any time ago, before GPSs got so good, is quite often wrong in the vertical direction, often by several meters or more. . Another alternative is RTK GPS. Even cheap GPS now are more accurate than many maps. You should go to both locations and get a GPS fix on both of them - after letting the GPS run for some time (the fix gets more accurate as you stay in one place for awhile. Elevation is particularly problematic for some GPSs. Its often wrong, unless you take care to apply all the necessary corrections. GPS fixes on altitude are often quite a bit less accurate than horizontally. So you have tobe willing to get more accuratye elevation data and teh way to do that is via GPS "precise polt positioning or real time kinematics.. RTK. See rtklib.com for an open source GPS technology that can give you very accurate data and not cost an arm and a leg.

Scan the academic literature. Maybe there is soome way you can push your signal through the trees using diversity or beam forming or mimo or something.

Math!


Quote from: Halcyon on Today at 21:15:27>Quote from: IanB on Today at 21:06:43

One thought I have about trees, and the impossibility of trimming them, is that trees grow. Treetops that are only slightly impinging this year could grow much further into the sight line with each following year.

I did think about that. Most of the trees here are fully grown so they shouldn't get much larger. The occasional storm and strong winds generally take care of branches that tend to get too big.

[Brumby]

In my experience trees need constant attention. They're always growing bigger,so if you don't want them where they're growing you have to trim them back. When they die, you have to remove them or they may fall down on somebody. Trees require maintenance. There is no way around it. So budget for it, or face the fact that you'll have to cut them down and be done with it. (which sucks because lets face it, trees are often beautiful and being alive they arguably have life and interests on some level. Cutting down a tree is killing a living thing. It never feels good. Animals live in trees. And so on.

Again, not knowing exactly where the Blue Mountains link will be placed, I cannot say with absolute certainty - but I can say that there is a very high likelihood that these trees will be in protected reserves.  No cutting or trimming is allowed - and often you are not even permitted to collect fallen branches as they, too, provide homes for creatures and eventually fertilise the forest floor.  If a branch happens to fall on someone, then bad luck.  The exception to this would be along recognised trails, where there is active maintenance to ensure the safety of those who walk them.

I feel relatively confident in saying this is very much a "hands off and deal with it" scenario.

[ivan747]

Rain fade vs frequency at several different types of rain:


http://www.e-band.com/get.php?i.119:w.698:h.478

I remember there are figures on fading by leaves and vegetation. I believe you just add a fixed figure to your margin, something like x dB per km. Try to google it.


There's also extra fading you have to consider in your link budget if you're going over a body of water, I believe it's actually scattering but I can't remember.

There are books on RF design, maybe you can pick up an old edition for cheap on eBay after sampling a new edition on Amazon.


Sent from my iPhone using Tapatalk

[Brumby]

I don't think bodies of water are going to be an issue.

The closest are the Nepean River and the artificial Penrith Lakes, but they are so close to the mountains that they are going to be well below any vertical beam spread.  The only other significant body is Prospect Reservoir - but it isn't that massive and it's a fair way from the Blue Mountains.

[cdev]

If you can find a place between the two terminuses of this link which has good visibility of both, you could perhaps (if you could get permission) mount a reflector there to complete the circuit so to speak.

Similar to how this is done on microwave towers. It could be something as simple as an old highway sign or similar. (a strong, flat piece of metal sufficiently large.) just mount it so securely its not going to move significantly in even the highest winds. Adjusting it properly might be difficult - thats where having he best possible elevation data comes in. (see below)

One thing that must be truly awesome is that Australia being south of Japan, also has coverage from the Japanese QZSS system and Beidou, the Chinese GPS system. Its my understanding that far more sats are visible in Asia for this reason. Just use a newer GPS that supports them.

I wrote a long post about RTKlib and hardware that supports it and setting up an RTK system but it may not be necessary IF you use a system that supports the newer sats available in your area. Thats important because the *vertical* accuracy of older GPSs often leaves much to be desired, that is to say its often way off. (typically the offset stays the same in a given area)  For some of my old GPS's the vertical direction is consistently overestimated. My real elevation as measured properly is substantially less than they tell me. This has to do with a bunch of factors, which you'll learn about if you explore RTKlib. (which is also a lot of fun learning)

Anyway, with that caveat getting an accurate position when you have a clear sky view is fairly easy and with the multi-constellation units is fairly rapid, even without RTK. especially if the unit has been running for awhile with its antenna having a good view of the sky (on top of the car that gets you there?) Make sure your fix quiets down after you turn the unit on have it still and running for awhile with a good sky view before taking your measurements.

So anyway, one of my GPS's that seems extremely accurate and supports GPS, QZSS and Beidou - my navspark mini, cost me less than $10 and gets Beidou sats (only one or two are ever in view here in he US) But those sats add to the quality of the fix significantly. Enough for the indoor movements of the GPS's antenna to seem accurate. (for example, moving the antenna from next to the window to computer desk, a distance of around two meters, was recorded with what appeared to be fidelity) This is without DGPS of any kind, inside of a two story wooden house with the usual levels of wiring and stuff in it. That's very impressive to me. So, you likely would get even more accuracy, being in Australia because of the way these newer GNSS satellites orbits are designed to keep them over one part of the world, as the earth turns beneath it. The QZSS system was designed to augment GPS for very densely populated Japan, and he fact hat Australia is directly south of Japan means it spends as much time over Australia as it does Japan. So you get that extra accuracy for free. Similarly with Beidou and China.

Record a log and record the time so later you can correlate the two and when you get home figure out what the exact heading and elevation the links between them would need to be.

Do this by making a coverage map in one of the aforementioned programs using the exact same scale (and if you ca perhaps also the same coordinates to define the image borders) and then overlay the two in an imaging program and "diff" them, start in the "difference" layer mode perhaps and the areas that are covered by both signals at the highest level should be visible.

Those places likely would be good spots for a reflector!

[Brumby]

Unless there is a clear view of the Sydney basin in some other direction, that's a lot of work ... to achieve nothing.  Even if there was (which, knowing the typical situation of residences in the Blue Mountains, is not likely) the additional distance the signal would need to traverse could possibly (likely) result in more losses than the wet tree leaves.

There is about 40-50 metres worth of tree canopy within 20 metres of one side of the link. I just can't get quite high enough to clear them completely.

So, about 70 metres from the mountain top location, there's clear line of sight.  The only place to put a reflector would be somewhere in that 70 metres, hovering above the tree tops.

To me, other than assessing the options, the best solution is going to get as high as possible at the mountain end.  You face issues with council regulations and cost - to get something high enough and rigid enough to do the job.

[Halcyon]

To me, other than assessing the options, the best solution is going to get as high as possible at the mountain end.  You face issues with council regulations and cost - to get something high enough and rigid enough to do the job.

I tend to agree. Adding reflectors, bouncing the beam off objects etc... is out of the question. If I had access to an intermediate site, I'd just throw a repeater there.

I think the answer here is to get slightly higher (which I can at one end). If the trees weren't there, I'd buy the gear tomorrow as there is direct line of sight.
This week, I'm going to try and borrow a telescope to visually confirm the path. There is a narrow path between trees which might just be enough.

[cdev]

A repeater would be much better than a reflector if its possible.



Quote from: Brumby on Today at 02:03:36

Unless there is a clear view of the Sydney basin in some other direction, that's a lot of work ... to achieve nothing.  Even if there was (which, knowing the typical situation of residences in the Blue Mountains, is not likely) the additional distance the signal would need to traverse could possibly (likely) result in more losses than the wet tree leaves.
>Quote from: Halcyon on 2017-09-14, 03:12:36

There is about 40-50 metres worth of tree canopy within 20 metres of one side of the link. I just can't get quite high enough to clear them completely.

So, about 70 metres from the mountain top location, there's clear line of sight.  The only place to put a reflector would be somewhere in that 70 metres, hovering above the tree tops.

To me, other than assessing the options, the best solution is going to get as high as possible at the mountain end.  You face issues with council regulations and cost - to get something high enough and rigid enough to do the job.

[Halcyon]

I had the pleasure of meeting forum member vk2amv this afternoon who dropped off some decommissioned Ubiquiti radios and dishes for me to play around with.

For anyone still following this thread, I'll be doing some testing with these over the next few weekends across the 55 km proposed link path and will post results, experiences and photos in this thread.

@vk2amv -- Drinks are on me when we next meet!

 

[Brumby]

Kudos to vk2amv !!      

This is going to be a big help!

[cdev]

How very very cool!


****GOOD LUCK!!!****

Will be following this-

Please take some pictures and screenshots and post them so we know what the equipment, terrain and link signal parameters in the real world testing look like!

[Halcyon]

I've been thinking about how to mount the dish (as I don't have a TV mast on my roof). I have a brick wall where I can attach a mast directly to several points up the wall and have it protrude past the roof line.

I'm not paying ridiculous amounts for a "proper" antenna mast, which is essentially just a metal pipe. I thought about using 900mm lengths of 20mm diameter galvanised steel pipe such as these: https://www.bunnings.com.au/kinetic-20-x-900mm-galvanised-pipe_p4700271 or alternatively https://www.bunnings.com.au/arc-2-4m-32nb-galvanised-steel-pipe_p1100586

It's cheap, I can built it as high as I need with screw-on joints and it should be sturdy enough to withstand strong with without flexing too much.

Does anyone have any thoughts?

[Brumby]

I'd be inclined to minimise the number of screw on joints.  If it can be done, a single length is going to be more rigid.  Mounting points will need to be rock solid, obviously - and I wonder about how much movement there will be on the dish under wind load.  The thought of guy wires to help stabilise the top of the mast did cross my mind - but I have no practical experience with these, so I don't know if they are a good idea or not.  (Points of attachment are the first question.)   ... but, then, this is going to depend on just how high the mast will reach.

[cdev]

You should figure out the wind loading with pencil and paper. Any kind of solid dish is likely to cause an extreme amout of wind loading in storms. Get a range of opinion. You want your antenna staying put in high winds and not becoming a projectile. Winds are getting stronger. Keep that in mind. Winds in 10 or 20 years time may be significantly stronger than today. Think ahead.

I've been thinking about how to mount the dish (as I don't have a TV mast on my roof). I have a brick wall where I can attach a mast directly to several points up the wall and have it protrude past the roof line.

I'm not paying ridiculous amounts for a "proper" antenna mast, which is essentially just a metal pipe. I thought about using 900mm lengths of 20mm diameter galvanised steel pipe such as these: https://www.bunnings.com.au/kinetic-20-x-900mm-galvanised-pipe_p4700271 or alternatively https://www.bunnings.com.au/arc-2-4m-32nb-galvanised-steel-pipe_p1100586

It's cheap, I can built it as high as I need with screw-on joints and it should be sturdy enough to withstand strong with without flexing too much.

Does anyone have any thoughts?

[Halcyon]

I'd be inclined to minimise the number of screw on joints.  If it can be done, a single length is going to be more rigid.  Mounting points will need to be rock solid, obviously - and I wonder about how much movement there will be on the dish under wind load.  The thought of guy wires to help stabilise the top of the mast did cross my mind - but I have no practical experience with these, so I don't know if they are a good idea or not.  (Points of attachment are the first question.)   ... but, then, this is going to depend on just how high the mast will reach.

I'm thinking of mounting about 2 metres of the pole at several points along the brick wall (with clamps similar to saddle clips, but stronger) then have another ~2 metres protruding up past the roof line. I don't think I'll need anything much higher than that.

You should figure out the wind loading with pencil and paper. Any kind of solid dish is likely to cause an extreme amout of wind loading in storms. Get a range of opinion. You want your antenna staying put in high winds and not becoming a projectile.

The dish, radio and supplied brackets are good for up to 200km/hr winds. Obviously the mast will need to withstand that as well. I'm looking at about 8.5 KG of weight on the mast.

[cdev]

Even a relatively short two or three meter mast is a LEVER with all that implies for strength of force. So, if you go up any distance, guying is absolutely essential unless you want to use a trussed steel tower.

With guying you can reach for the skies and have an antenna system thats unlikely to fall down in 95% of all storms. If you're lucky that other 5% misses you!

Don't even think about using a tall mast without it, it wont work, even with the strongest steel pipe.

I'd be inclined to minimise the number of screw on joints.  If it can be done, a single length is going to be more rigid.  Mounting points will need to be rock solid, obviously - and I wonder about how much movement there will be on the dish under wind load.  The thought of guy wires to help stabilise the top of the mast did cross my mind - but I have no practical experience with these, so I don't know if they are a good idea or not.  (Points of attachment are the first question.)   ... but, then, this is going to depend on just how high the mast will reach.

[cdev]

A mast has pieces that fit into one another. A guying system is just a ring and wires or very strong ropes that prevents lateral motion. The mast is not going up, it doesn't need to be attached strongly to the piece below it its not going to fly away, what it needs is to be prevented from going sideways even a small amount. If you have a tall mast you should use two rings with a minimum of wour guide ropes going to each one. You can use the same anchor points. Look at how they brace utility poles. Like that. You can use scrap wood to make enclosures for concrete pours and put anchors in the concrete so when it sets you'll have an extremely strong anchor post. It will last longer than you will. Concrete is very easy to work with. Even I can do it. They bring it to you and pour it in.

The most important rule is stay away from utility wires. Always assume your antenna is going to fall down someday. Make it impossible for it to ever fall on a utility wire and start a fire by physical distance. You'll notice you never see antennas anywhere near power lines. Thats because laws likely prevent their erection anywhere near them. .

[Red Squirrel]

Yep guyed towers hardly have any ground support, this surprised me the first time I saw it.





This is one tower I went at, it's probably about 150 foot tall if I had to guess.

That said if building a tower from scratch I would do self standing personally, less maintenance and simpler.  More expensive though.