wireless application

Have a relative with a cottage on a campground that recently put in free wifi for its members. But of course in her cottage she can't pick up the signal inside. Outside on the porch, she might grab signal at 20% or less, and hops around a lot. So I have been assigned with the task of "fixing her problem".

Here is the info I gathered doing a site survey... First of all, I do not administer the local signal being put out, so I have no specific details or control over it. Looks like they have an outside panel antenna mounted to a tower next to the main office. That's where the source is originating from. Her cottage is about 600 - 700 feet or so away from the originating antenna. Also through reasonable tree coverage, and over a small hill. I used a laptop with a usb wireless adapter and an active usb extension mounted to a pole. Walked around trying various spots and heights with Cirond WinC software to measure strength. What I found was at a certain location towards the rear of the cottage and about 10ft up, I would pick up signal at about 50% (I could never get more than that due to the distance I am guessing). By looking at the signal path visually, this was going through multiple trees, and one old building made of wood. by going up a minimum of 10ft, I was clearing the small hill. I am guessing they must be pumping out some decent power to be picking up 50% signal strength at a distance of 600ft or so and the trees & building.

So here is the plan I have come up with... On the cottage, install a outside yagi antenna (+13.9 db) at 10ft up, run LMR-400 cable (15ft) into the cabin, connect to a linksys AP (WAP56G) in bridge mode, connect that to a WRT54G and broad cast to cover her cottage (on a different channel). I am estimating I should be getting about 26 db of signal out.

I have set up several wireless systems, but not much to do with rebroadcasting applications. If I was picking up 50% signal strength with my little usb adapter, would that be enough to run the setup I am proposing? And to connect back at that distance? That should be about twice the power my usb adapter has.

I am interested in hearing feedback from anyone who might have experience or thoughts in a setup like this. Is this overkill, or do I need to use an additional amplifier? I want to make a good educated guess on what I need before I start buying stuff to just try.

And no I don't think I can go high enough to clear the trees and buildings to get LOS. That would take a full blown tower.

Thanks All !

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Reply to
joecool
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Chop down the trees and demolish the buildings. ;)

-- Don't bother me. I'm living happily ever after.

Reply to
sillyputty

Hmmm...that would describe a very direction antenna similar to a Yagi. Does the main office sit at one end of the campground and all the campers are in more or less a straight line in one direction where the flat panel antenna is pointed? OR...could that panle antenna be pointing to a backhaul somewhere and the actual local wireless LAN has a non-obviously seen omni antenna? If so and its not easily seen, that might be part of the problem as it should be on top of that tower.

Reply to
nevtxjustin

joecool hath wroth:

Really? How about a photograph of the equipment or the antennas?

At 700ft, you're going to need a directional antenna at her end.

  1. There is no such thing as a reasonable tree. Every time I've tried to convince a tree to let my RF pass, the tree rejects my pleas. I've tried various offerings and incantations, but nothing will make the tree pass my signals.
  2. Hills, whether small or large are even worse. Every time I try to invoke the hill god to let my signal pass, the hill responds with something like "eat dirt you worthless human". I suspect they are in colusion with the trees.

Good. That's the way I do it but I use an ethernet wireless bridge instead of USB. Actually, the last time I did it, I hung a wireless router running in client mode on the back of a dish. Whatever works.

I predict inevitable doom. It's easy enough to get a marginal connection almost anywhere you have signal. However, keeping that connection among the swaying trees and branches is going to be a problem. In addition, you're apparently skirting the top of a small hill, which probably puts it in the Fresnel Zone, which creates more loss and more weirdness. I think you could probably make it work, but I doubt if you can keep it working.

Try this simple test. Take you test pole and plant it firmly into the ground with some kind of temporary tripod support. Aim and position it as best you can. Then run Netstumbler for a while and watch the signal levels. My guess is you'll see huge variations as things move around (which includes you moving around).

My guess is that your unspecified model USB adapter was probably using the stock ceramic or PCB antenna found in most such bottom of the line devices. I'd give it an optimistic 0dBi gain. 6dBi is double your range so I think you have a chance if you get a halfway decent directional antenna. Notice that I said directional, not omnidirectional. I suggest you repeat the test using a decent directional antenna and perhaps 15 to 25 ft of the best coax cable you can borrow. The coax will present some loss, but the antenna gain should more than compensate for the loss.

Barf. That's the way we did it in the stone age of wireless. It will work but causes all manner or aesthetic and cable routing problems. I have one installation in an airport hanger where the router is hanging from the ceiling where the coax enters to keep things short.

Permit me to offer an alternative. Get a CPE (customer premisis equipment) client bridge what does PoE (power over ethernet) and has an external antenna connector. The antenna should be as high, big, and ugly as possible. However, if it does not clear the hill, don't bother, it's not going to work no matter how big and ugly. A small antenna up very high is much better than an a big antenna down low. Concentrate on the antenna as everything else is secondary.

Run outdoor (gel filled and UV proof) CAT5 from the CPE bridge radio to the local router or computer. Some client bridges can handle more than one MAC address so you may not need a router.

That leaves the selection of the mysterious radio. Anything that calls itself a CPE, client bridge, customer radio, ethernet client bridge, or similar buzzwords will work. Lots of indoor devices, such as "game adapters" will also work, but will require waterproofing. Some possibles:

There are lots of others, but I'm too lazy to dig them out with Google.

There are also versions that integrate the radio into the antenna:

Make sure they'll do PoE or make sure you can get a PoE adapter (that is really a 48VDC 802.3af adapter and some some simulated kludge).

26dBm(?) out of what?

Consider yourself fortunate. Methinks repeaters, WDS bridges, and mesh networks to be a nightmare. Avoid if possible though they all are tempting. Incidentally, thank you for not suggesting putting a repeater on top of the pole.

Dunno. Run this simple test. Setup your USB gizmo as a wireless client. ping the access point continuously with something like: ping 192.168.1.1 -t If you get a consistent 2-6msec latency for the entire test duration, I'm sure it can be made to work. If the latency is all over the map plus some timeouts (which is what I would expect), you have some chain saw or tower work to do.

Sigh. Double the "power" which I presume means the transmit RF output, and you increase your range about 1.4 times. You'll barely notice the increase in signal strength. It will also be in one direction only as the other end will need to increase its power identically in order to get a symmetrical improvement. That's another reason why I suggest you concentrate on the antenna and not the radio.

Lots of experience. I live in a dense redwood, fir, and oak forest. We're lucky if we can see the sun, much less get any RF through this mess. I've done quite a bit of experimenting, which includes repeaters, passive reflectors, brute force power, antenna games, and beam forming. They all work to some degree, but there's no replacement for real line of sight and a clear shot.

Argh. You said a dirty word. Amplifiers are nothing more than expensive jammers. You do NOT get much of range increase if you can't hear the response from the other direction. On the other hand, antennas increase the signal in both directions simultaneously. Think antennas, not radios, amplfiers, boosters, and range extenders.

Educated guess is an oxymoron. A calculation would be more interesting. However, I would need to know something about what equipment is at the access point, the antenna pattern, exact locations, line of sight, tree type, tree density, hill location, etc. It's too much for doing this via usenet. You might have to settle for an uniformed wild guess, which is acceptable if the store has a good return policy.

Why would you want to blow up a perfectly good tower? How many feet high would it need to be? Up to about 30ft, a pole will work just fine. Radio Shock sells a usable 30ft push up pole.

You might also consider going underground to some place with a better line of sight. I have quite a bit of buried cable running around the forest and under the road. It's a bit of work, but not impossible. Local forest soil is mulch, which is quite soft and easy to work. I've used black flex sprinkler pipe, with CAT5, coax, fiber, etc shoved inside.

Reply to
Jeff Liebermann

I would not say like a yagi, as some panel antennas can cover 30 degrees up to 120 degrees. Like the sector antennas on the cell sites.

Reply to
Dana

I have had good luck with a chain saw on some trees that were growing to tall around my radar sites which had microwave antennas pointing towards a repeater on the hill top.

Depending on size of hill and height of antennas OFDM is an improvement over the older radios. But yes hills tend to block microwave frequencies. Especially the ones that infringe on your Frensel zone clearance.

If you use an amplifer, as Jeff said that is one way only, you would need an LNA (tower top amp) for the receive side.

Reply to
Dana

In some panel antennas, true. On other flat panel antennas like I use with 28 dB gain and less than 5=BA beamwidth, its even closer to a dish antenna. So it could be very similar to a Yagi.

Reply to
nevtxjustin

In some panel antennas, true. On other flat panel antennas like I use with 28 dB gain and less than 5º beamwidth, its even closer to a dish antenna. So it could be very similar to a Yagi.

Point I was making is that it would be very misleading to assume a panel antenna is as directional as a yagi. More times than not a panel antenna covers a sector of interest.

Reply to
Dana

snipped-for-privacy@gmail.com hath wroth:

Lots of different types of panel antennas.

There are 2.4GHz panel antennas with multiple phased 3-5 element log periodics inside. They're easy to recognize because the fiberglass radome bulges forward in a wedge about 4-6" high. I forgot who makes them. Some of them are extremely broadband, covering everything from the 800MHz cellular band to the top of the PCS band at 2000MHz. However, the one's for 2.4GHz are much simpler.

More common are Franklin antennas. See:

These have a wide horizontal beamwidth (70-150 degrees), narrow vertical beamwidth of about 5-10 degrees with lots of gain. Great antennas and really easy to build. I use them in place of omnis.

There are also arrays of 2.4GHz patch antennas on a large substrate. Most of these are on a square base and have equal beamwidth in both axis's. Here's a small version:

Well, rectangular but close enough.

There are also slotted waveguide antennas, which are made to look similar to a common cellular/paging sector antenna to make mounting easy.

I'm not going to speculate on what the WISP used in the install. Get a pair of binoculars and read the serial number tag. Try to guess where it's pointed and how far off the center line to the cabin. If the angle is large, you may be out of the pattern making connectivity problematic.

Reply to
Jeff Liebermann

Although putting a client bridge up with the antenna is probably the optimal solution for neatness and gain, the approach you are considering is also workable. LMR 400 will allow you to put the router inside. At .25 db loss per meter, you can run 8-10 meters of coax with acceptable loss.

As Jeff said, it would be helpful to have readings from netstumbler in db. Saying 50% does not indicate much. And check them over time. In my experience, if I can get consistent 10 db above the noise with a built-in antenna, then a decent antenna will get me over the hump. You are looking for 20 db SN minimum in the final setup.

And do see about that ping consistency in a fixed spot next time you test.

As far as using a yagi or panel antenna, yes, it makes sense, but I do wonder if your USB's omni is working off reflections. As you narrow the pattern on the antenna, you may actually eliminate a working reflection? NOT a reason to choose omni, just a possible reason you might have trouble with a narrow antenna.

Only way to tell is to test with a directional antenna.

Worst case, you find a nearby spot for the antenna (on the hill?) and do as Jeff said, running buried ethernet cable from a pole-mounted ethernet bridge-in-a-box to the cabin.

Steve

Reply to
seaweedsteve

seaweedsteve hath wroth:

Quiz question: You have a 45 degree (1:1) pitched roof (this is Vermont where they have snow). The house is 25ft wide. The roof overhangs the walls about 3ft. Walls are 8ft high. The antenna mast on the roof is 10ft long. How long an LMR400 coax run from the dish antenna on the top of the mast, to somewhere useful inside (on a desk)? Don't forget the drop loop and you can't drill through the shake roof without trashing the roofers warranty.

Before I grind the numbers, make a guess as to how much coax and see how close you get.

Starting at the dish antenna feed, we have 2ft of coax between the dish feed and the pipe including a drip loop. Add 10ft for the mast. The roof is: 1.4 * 12.5ft = 17.5ft Going back to the outside wall is about 3ft (including the drip loop). Down the wall to the floor (on the outside) is 8ft. Through the wall, into the room, and back up to a desk, add another 6ft. Grand total: 2 + 10 + 17.5 + 3 + 8 + 6 = 46.5 ft Actually, that seems a bit low. I've done something like that with pre-cut 50ft lengths of LMR-400 and come up short.

For LMR-400 I use .23dB/meter or 0.07dB/ft. 50ft would be 3.5dB loss which is tolerable. My objections to using LMR-400 were not because of attenuation, but because of the difficulties handling the stuff, going through the walls, dealing with the pigtail, and potential water/freezing problems.

Reply to
Jeff Liebermann

In that case, I'm probably starting to think ethernet and a Rootenna and wondering about the temperatures.

But honestly, though I've never installed a roof-mounted antenna, I would be working to reduce that run. Gable or Hipped roof? If gabled, then a stand-off from the wall on the gable end? Dormers? Absolutely no roof penetrations that I can take advantage of? Thru the Ridge vent into the Attic?

In our case, I put the antenna on a pole and tied it up in a tree, looping the cable over to the eave. The antenna sits a foot above the tree's crown. Grounded at the base of the tree.

I agree, the setting and requirements of the user (this room not that room etc) dictate the solution. The longer the run must be, the more ethernet makes sense.

I mainly just want to round out the answer to the question and reinforce the idea that coax (LMR400) IS a reasonable approach for runs under 50 feet.

Alternatively If you or somebody had pointed them to Coax, I would have mentioned the box-on the-mast alternative !

I suppose that apart from the loss question, one can weigh out the additional hassles of each: Lightning devices and pigtails with a cheap router vs POE and more expensive CPE rig....

Steve

Reply to
seaweedsteve

seaweedsteve hath wroth:

I'm assuming that some effort will be made to waterproof and temperature stabilize the radio. Cold weather is easy. The heat from the radio will be enough to prevent water condensation and circuit failure. For high temps, an extra metal plate to act as a heat shield and everything painted glossy white is sufficient. The power consumption of the current crop of wireless bridges is somewhat less in the bad old days of trying to remove 20 watts of heat. Some small client radios burn only 5-7 watts. USB radios burn only 2.5 watts maximum.

Honesty will cost you extra.

All of those will work well. Running the coax or CAT5 through a vent will reduce the exposed cable run. However, we're talking about a

10ft pole, which may require guy wires. That will move the pole from the ends of the roof peak, to somewhere near the middle. The coax run gets longer, etc. Also, there's no way to run LMR-400 coax and make it also look nice. In areas that have CC&R's, such aesthetic abominations are always a problem.

I've done some installs with the antenna inside the attic. 2.4Ghz will sorta go through wood fairly easily. It will not go through tar and rock shingles. It has problems when the wood gets wet, and fails completely when there's snow on the roof. Still, for some areas, through the roof or side wall is a usable alternative.

No wok or salad bowl dish hanging in the trees?

Yep. If I can put the antenna in a window, where the coax cable is very short, then I would certainly do that first as it's the easiest. However, a 24dBi dish is about 2x3 ft big, which doesn't lend itself to indoor installations.

Sure. However, not if you're trying to squeeze every last bit of performance out of the link. Decibels are expensive.

Well, if I had mentioned both, would you have suggested a reflector on top of the pole with a dish antenna pointed upward? (Periscope antenna). With a high gain dish, that is a workable but mechanically critical solution.

Don't try it in a tree. The tree moving will ruin the aim.

Good point. There's very little lightning in my area, so it's not even a consideration. At the prices of wireless bridges these days, they're cheaper than a Polyphaser lightning arrestor.

Reply to
Jeff Liebermann

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