I have an application wherein we need to communicate with a PC server from a remote office to our main facility some 24 miles away. We have ISDN service to both sites which communicate back to our main office and thence to each other. Due to the remoteness of the area and numerous thunderstorms which cause downed telephone lines, power failures, etc. it is unreliable and especially so when you most need it.

Has anyone had any successful experience with ethernet radios over long distances? I dont need a great deal of data throughput but it needs to work every minute of every day. Given the importance of seeing the status of the information, money is not a huge factor except fiber optics or other direct wire connection would likely be too expensive. Undetected equipment downtime (especially system wide) is costly.

The ethernet radios they have tried before (with short antennas) are shown here.

The terrain is flat between the two sites. Any suggestions or experience?

how far is "long" distance. Specifics help.

there are many solutions that are MUCH better than those "ethernet radios". FHSS is awful for bandwidth. From the specs on that site, probably worse than the ISDN in practice.

sorry, didn't read your post well enough.

for 24 miles, I would suggest renting space on a tower about half-way inbetween (water towers work well) and use an 802.11[abg] packaged solution.

Look for 5.8ghz gear, it will keep you off of the over-loaded 802.11ag spectrum

Thanks for the information. This area is very remote. We will likely have to construct tower(s). We already have a 190' tower going up approximately 7 miles from one end. We can build as many more as we need (190' towers are around $13,000 each). Can we set up wireless 802.11 with repeaters? Any specific sites you can refer me to for a packaged solution? Is this what I should be looking for?

We used to do a lot of this kind of thing, and it works well...the only problem with basic 802.11 repeaters is you lose bandwidth each time. We were getting around 40-50% bandwidth lost with each hop.

Depending on what you are allowed to do there, you might find using a licenced band allows you to go for very high gain antennas and run it in one hop - which is the way power and telco folks tend to do it.

The 5Ghz band is good, bud sadly has a shorter effective range than 2.4Ghz, and you probably won't get too much 2.4 traffic if you are as far away from civilisation as it sounds.

Also, depending on how "remote" you're talking about, does the remote location have cellular phone towers in range? Maybe you can use cellular data as a backup to the ISDN line. This depends, of course, on how much bandwidth your local providers are offering and whether they're vulnerable to the same issues that are driving you to a custom wireless solution in the first place.

Cell coverage is sketchy at best. We do have cell phone back ups for reporting status of remote equipment but those failed as well this weekend. I think what we have decided to do is erect a 200' tower at the main facility and move the server to main facility and relay with a spread spectrum repeater off the proprietary spread spectrum radios hitting the repeater.

The microwave idea is being looked as an alternative at although nobody seems to know much about it (that I know).

A quick search reveals these products:

http://www.microwavedata.com/products/spreadspectrum.asp?pid=304

The 900MHz ones claim to have 60 mile LoS connectivity with the right antennas.

The microwave idea is being looked as an alternative at although nobody seems to know much about it (that I know).

To find out about it, call one of your local radio stations and talk to the chief engineer. These days it is rare for the studio to be located at the transmitter site, and the audio signals and transmitter data go back and forth using a microwave link.

It is not horribly expensive -- peanuts compared to the cost of a 200 foot tower! -- but still a couple thousand dollars, and you'll need FCC licensing for it. Where I work we have four radio stations communicating via microwave to two different transmitter sites, one of them about 8 miles away, the other about 12, and to my knowledge there has not been a single second's downtime due to failure of the microwave system in the 12 years I have worked here.

tanstaafl.

If you want to brew it yourself, try these two
http://www.fab-corp.com/
http://www.demarctech.com/

If you want a boxed solution, Cisco, Alcatel, and others sell 5.8GHz solutions that are either 802.11a compatable, or proprietary. There is also Motorola's canopy gear. WiMax based stuff is probably also worth googling for.

a 200' tower at 7 miles from each end point of the link is probably the MAX you should need.

I've used Hyperlink Technologies successfully too, and they have pretty good prices.

Not all of the solutions need an FCC license. In particular, the page I linked contains products that don't need an FCC license to operate.

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peanuts compared to the cost of a 200 foot tower!

We are thinking both towers are going to be necessary to cover the other telemetry system (which feed the server). The microwave link sound is interesting. We are looking at it now. Thanks to all.

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The 900MHz ones claim to have 60 mile LoS connectivity with the right antennas

We use a lot of MDS radios on some licensed dedicated frequencies in one of our facilities. We have a single 440' tower at that site which pulls in data from about a 40 mile radius.