Testing the Range of the SMC2655W

Getting It Up

I had been wanting to do some "testing" with the external antenna and enclosure I had built. I say "testing", because testing usually involves a plan and a clear set of goals and measurements. I just wanted to see what kind of range I could get.

When Darren offered the use of his crank-up antenna I jumped at it. He said it would get about 35 feet in the air. He was interested in using 802.11b to share DSL with his neighbor across the street, or possibly using an antenna to provide DSL-over-wireless to some nearby neighbors. The question was, how nearby did they have to be?

Darren doesn't do heights, so he held the ladder while I went up on the roof.

I had to remove the clamp holding the crank-up antenna from moving, and attach the wireless antenna to the top. Darren cranked down the antenna, and I used cable ties to secure the wireless antenna to the top of the mast. The gray cable hanging down is the ethernet cable carrying Power over Ethernet on an unused pair.

Darren got the cables connected down below. There wasn't much. I had brought a small Belkin router to act as a DHCP server. Darren powered that up, then plugged the cable from the wireless antenna into the router, and then powered up the wall wart that supplies power to the PoE injector. Everything, theoretically, was working.

Now he got busy cranking. Here is the antenna in its fully extended position, with the white wireless antenna at the top. It doesn't look that high, but remember that I was standing on the roof when I took the picture. It's 15 or 20 feet from the roof peak where I am, to the ground.

Here's a shot from down the street giving a better idea of how high the wireless antenna is.

Checking It Out

We walked down the street with a Dell Axim Pocket PC, with a Linksys Compact Flash wireless card. I used the client software from Linksys to see what the signal strength was. It updates every second or so, so you get a good idea of what the strength is everywhere. You can see the antenna again in the background behind me.

I brought along a handheld GPS. I set a waypoint at Darren's house next to the antenna, and then set the GPS to give a bearing and distance back to the waypoint. This way as we walked along we knew how far we were from the antenna. We got a solid usable signal (about 20%) out to 0.1 miles (528 feet). We got an intermittent signal up to 0.2 miles (1056 feet). That was line of sight; the trees really killed the signal.

One of Darren's next-door neighbors let us come into his house and check signal strength there. I got 20% to 33%, easily enough to handle the bandwidth of a DSL connection. It was a concrete house, but it took me a while to understand that the house was not built of concrete block, but was actually a poured concrete house. I think the signal was really coming through the roof from the antenna high overhead next door. No other neighbors were home to let us try their houses.

So it was time to go mobile.

We loaded up the Toshiba notebook with an Orinoco wireless card and a 5dBi magmount antenna on the roof. The GPS was on the dash, and we had the Pocket PC for backup. The results were pretty consistent with what we had seen before: usable signal up to 0.1 miles, intermittent signal up to 0.2 miles. We also did a little checking to see if any of Darren's neighbors had open APs so he could get out on their DSL, but it had been so long since I went wardriving that I didn't have netstumbler on this notebook. Instead we had to use pocket warrior on the Pocket PC. With the small built-in antenna in the CF card we didn't get much signal, and only saw a couple APs with "default" SSID that were too far from the house. It might be possible to pick the APs up with a directional antenna, but probably not.

Writing It Down

So we went back to house and took down the antenna before the lightning storm hit. We sat around and considered options. Darren's neighbor has a Windows XP box with an internal USB DSL modem. This means that the Windows XP box would have to be on for Darren to use an AP connected to it. One possible alternative would be an all-in-one wireless DSL router, which would connect to BellSouth, provide AP functionality to make the DSL available over wireless, and allow the XP box to plug into the router via ethernet cable. Of course, those boxes cost $200. Since Darren is familiar with building PCs, he might be able to fake it by putting the USB DSL modem into a quiet little PC, and connect the PC to a wireless router to connect to his neighbor, and to Darren. In either case, the wireless router would use a directional antenna in his neighbor's window, and on Darren's roof or window.

Another option would be for Darren to get his own DSL, and put an omnidirectional antenna like the one we tested on his roof. Then he could sell DSL service to his neighbors cheaply to defray his costs. The DSL bandwidth should be enough to handle everyone within range. This would completely violate the Terms Of Service agreement with BellSouth, but it's technically possible.

It was an educational day. Next I want to get the antenna mounted at my house, and see if my neighbors can hit it.