atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services Cabling Telephones Systems Wiring Aerial cable across busy street, wireless, or PTP T-1

We have an account that is expanding to an office across a busy street. It is only about 200ft.

A PTP T-1 is $575/m from the telco. Damn, that is a lot of green for what is essential a virtual Cat5 wire than runs 200'.

They are going to be in the space for at least 5 years - signing a 5yr lease. $34,500 over 5 years.

There are utility poles in line, owned by Portland General Electric I am sure, but I just don't think there is anyway a contractor (out of our league; we can't stop traffic, etc) could do to get cable across.

Building A has about a 12ft roofline (single story), Building B has about a 10ft roofline; both structures have flat roofs.

Trucks, semis, etc, up and down the street all day, so line of sight would have to be a tall antenna or dish mounted up high.

Bandwidth is not a big deal, only 8-9 people at building B and we could put IP phones in there.

Anyone have any ideas? Know of any company in the Portland OR area that would be interested?

The telco wants 5-6 weeks lead time for the PTP T-1 because of facilities at Building B, so time is running out on the second option.

Thanks for any ideas. This is a non-profit that helps homeless people. Really a great group of people and they would rather spend $575/m on helping people if they could.

I did more research and it looks like the only wireless solution would be something like Bridgeport's model 60 unlicensed units mounted up high on poles. That would give interference-free 4GBs bandwidth even in bad weather.

The only problem of course is cost. It looks like that solution would run $26k-$32k at a minimum. Then there are a the possible maintenance/failure issues over time vs a physical PTP T-1. Still looking.

Look for outside wireless bridge products. Trucks are not supposed to exceed 13'6" in height so a mid level antenna on either side should suffice.

We have no experience doing this, but we might give it a try. There is a lot of lower end or used equipment on the market that doesn't require a license. We would only do it for a customer like this though, they are the best.

I agree with a GOOD quality point to point wireless. One of the ones we have used in the past is Proxim . Not the cheapest, but they do have a really good, stable product.

To cross a street, you typically need the permission of the appropriate government agency (city/state/county/etc). You also may need to lease space on the poles. I've done it, but it's not easy and it is easiest if you find someone who has been through the process before (I always use a contractor with experience with this).

I agree with all the other comments - use wireless bridges. Keep the power down to what gets you a stable connection (if you bump up the power more than necessary, you'll interfere with others on frequency, which causes them to transmit more to get around your signal, which lowers the speed for everyone - you included). Use directional antennas.

If you plan on using this for computers too, I'd recommend implementing some sort of quality of service (QoS). I'd recommend a separate bridge, on a different frequency, for the computers if you can't do QoS.

Of course it depends on how important the phones are for the other office. Are they calling the public or is this intra-office-only communication? Also, what are you going to do for 911?

An alternative: use wireless for network and some sort of OPX (Off Premises Extension) line. Cost of the OPX lines should be similar to the cost of a POTS line, although you obviously will need one for each phone. The advantage over the bridges is that it should be rock solid once set up.

I did this for a customer who is "cost conscious" and did it with inexpensive D Link access points and directional antennas .... and had very good luck with it.

They have 4 or 5 computers and IP Phones in the outbuilding.

We worked a good deal on a YDI Wireless Link CX-24; which is/was eventually bought out by Proxim. A seller close by had one at a good discount. It is set up for ethernet, up to 45mps/90mps duplex. Can go up to 3 miles or so apparently. Overkill to cross a street I am sure, but the price was right.



The CX-24 is a used 2004 product, no license required, and apparently will do the trick. The main building has a nice CB antenna 16' mast w/ guy wires - very solid - that is unused. On the other side we'll use a weighted, non penetrating mast/base. We have to avoid transmitting through power lines that start at about 18' on the Building B side. The A side has power lines that don't start until about 21', so we'll aim it on an incline to try and get as high as we can over traffic, but not be aiming through the wires.

So, we have about a 4'-5' 'hole' between the lowest power line and highest truck traffic on the B side. I imagine something powerful enough to transmit three miles can overcome just about anything for 200'-250'.

We'll give them a great price, give it a try with the agreement that if we can't get it working, they'll have to go to a wireless professional or to the PTP wired/telco T-1. I've made it clear that we are amateurs at this, but we are also adventurous nerds who would like to help out a homeless shelter.

Our service manager put a 12' C-band dish in his back yard (his neighbors love him) so if he can do that, I trust he can pull this off.

It appears that this wireless bridge acts just like a switch. Plug in a 24-port 10/100 switch at Building B and we are off and running ... no CSU/DSU/Router like a T-1 PTP connection.

The seller claims 1ms ping rates and the 45mbs is real, so I don't think IP phones should have trouble, QOS or not.

For the wiring that runs to the 'dish' there is ethernet - no problem we have outdoor rated wire, but what about the power/48v transformer/power leads. How to protect it from weather, sun. Put in flex conduit? Plastic 'spring' conduit? On one install I saw that a guy used a garden hose . Oh well, we'll come up with something.

FYI, for future reference, most municipalities require 14 feet in alleys and 18 feet over public roadways. It's been 10 years since I did an across-the-street areal, so it's probably higher now. And on public roadways, always go as high as you reasonably can. I could tell you a story, but I wouldn't believe it, if I hadn't seen it! (23 feet wasn't enough)