10 mile point to maultipoint

It can be done, but it isn't easy and it's not for everyone. In the Wi-Fi "shootouts" a pair of hams came up with 65 miles. But, for the usual wi-fier probably a half-mile. For the long range stuff large exponentional antennas accurately aimed etc. are needed. Luck

We are going to place the AP on a 400 foot tower. We are going to lease a spot at 225 feet.

Hope this is high enough to get 10 miles.

Hope is a good thing. Calculations are better.

See:

miles requires that you only be 38ft above the average terrain to keep from hitting the curvature of the earth. At 225ft, you can go about 40 miles before running into the ground.

Any other calculations will require some input like frequency, tx power, receive sensitivity, modulation rate, antenna gains, coax losses, and path obstructions. Lacking those, there is always hope.

Bah-humbug. Aiming even farther distances is easy if you do some preparation. The problem is that the boresight alignment of most high gain dishes and panels is not exactly the same as the maximum lobe of the antenna. I clamp on a cheap plastic rifle telescope, point it at a known source of 2.4GHz (away from any reflections or edge diffraction), and align the telescope to agree with the antenna gain maxima. I carefully drag it to the site, get some lunatic to haul it up the tower, mount it, make it vertical with an electronic level, and aim it at the other end of the link with the telescope. It usually works the first time. The antenna must be assembled before transport to the mountain top which may be a handling problem for big dishes. Also, it's a good idea to think about where to clamp the telescope so that it doesn't hit the tower or mounting (oops).

I recently borrowed a $100 green laser which can certainly be seen at

4 miles, and will probably work much farther.

I was commenting on the usual lack of numbers necessary to do such calculations. Incidentally, 802.11b/g tends to having timing problems at about 10 miles.

For coverage and point to point links, I use (free) Radio Mobile:

the SRTM (shuttle radar topography mission) 1 arc sec maps. ftp://e0mss21u.ecs.nasa.gov/srtm/United_States_1arcsec/1arcsec/ The program will download and optionally save the maps as needed and can use them in the original zipped format.

See the "path profile" example at:

typical output.

I also use various Topo programs to generate point to point path profiles of the terrain, and then just use a ruler or drawing program to connect the end points. It's not as accurate and offers no help with Fresnel Zone clearances or terrain irregularities, but works well enough for testing simple clearance.

In this case, the OP is doing point to multipoint which requires an map area coverage simulation to see what areas will work. Here's a very bad example of a 3D VHF coverage model for a local ham radio repeater.

2.4Ghz model will be different. I can post better examples if necessary.

Drivel: About 40 linear feet of bookshelves just peeled themselves off the wall and onto my kitchen table. I guess I'm not a great carpenter. Kinda reminds me of the 1989 earthquake. I know what I'll be doing for the next few days. Argh...

The fun bit is aiming .. 10 miles is very achievable but the aiming .

have fun .

documents a 7KM link. He talks about using topo and aerial photo maps to document the terrain changes between the two points, looking for path obstructions.

There are commercial services that do the same thing, but I seem to have lost the references (too pricey for me).

WOW!

Thanks all for your input. I will keep you posted on what we do. We have to get this system up in the next 3 months. We are looking hard at the

system seems nice.

Thanks again,

Tracy

Craig went through great pains to plot the clearances across the terrain, noting the altitude at every contour line on the map. That sounded like an awful lot of detailed work. The commercial solutions that I looked at the time were only for certain areas, and were pricey. If there are free solutions that have appeared in the last four years, I wouldn't have noticed.

I suggest WRAP boards + Atheros 5004x + StarOS. It's very good solution for long range links 2,4 or 5GHz + very stable system.

SID