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Why you might not need an expensive wireless site survey kit

In this Q&A, one wireless engineer shares how she built a wireless site survey rig for less than $40 using supplies from a hardware store.

In this edition of "The Subnet," we catch up with Jennifer Huber, who designs, tests and deploys wireless networks for clients of World Wide Technology, a large systems integrator based in St. Louis. She also maintains a blog, I ♥ WiFi.

What are you working on these days?

I've been doing a lot of predictive [wireless] site surveys for customers that are expanding and don't have their buildings built yet, so we can't do actual AP-on-a-stick site surveys.

I saw an old blog post you wrote describing how you built a wireless site survey kit out of drywall texture brushes and office chairs. Do you still use those? How do clients react?

Yeah, people look at it kind of funny. There are site survey kits that are more professional and slick-looking, but they're also incredibly expensive. And they're usually really big, heavy and hard to travel with unless you're just driving in a local territory.

Jennifer HuberJennifer Huber

At my first site survey, I didn't have a rig at all. I was using phone wire to create a little basket that I used to hang the access point from a hook on the ceiling grid. I had to climb the ladder every time I moved the access point to survey each new location, and I said, ‘There's got to be a better way.' But that was back in 2006, so as I've gone along and met with other wireless engineers, it was actually a Cisco engineer who used that little drywall scrub brush [as part of the mounting bracket]. The drywall brush was the simplest because it already had holes that could line up with the access point bracket. I got the idea for threading the painter pole from him, and then [I added] the double paintbrush-angle adapter to get the access points to hang at the right angle. … You can go to any Home Depot or Lowes and set yourself up with a site survey rig for less than $40.

That post has been really helpful for people, and I've actually added to it as I get pictures of other people's site survey rigs to show how everybody else does it. There are some people who use magnets and spring mounts that raise it up, so it bends against the ceiling -- all kinds of nifty, interesting ways that people come up with. Somebody I know made a collapsible survey kit out of PVC pipes that can break down and fit into an overhead-bin, compliant-sized case. They don't have to go buy a painters pole; they just take the PVC pipes out of the case and pop it all together. They're all solving the same problem in different ways.

You've been doing wireless networking for a while. Is there anything that still stumps you?

It's a common misconception that if you have three or four [access points], then five or six would be better.
Jennifer HuberNetwork Engineer

Trying to get the information from a customer to do a client-density-based site survey, because oftentimes the customer doesn't know what type of wireless clients they're going to have. They don't really know what types of traffic the wireless client is going to generate, and they don't know if the traffic is local to the site or if it's going to go across the Internet. So it's really hard to get a good feel for what kind of bandwidth the wireless clients are going to be using in order to recommend the proper number for access points.

For example, one troubleshooting case I was on was at a private school that had carts they would bring into the classrooms with laptops, and they would distribute them to the students. There were about 20 students per class, and they often did lots of in-class stuff on a laptop -- except most of the traffic they were sending across the wireless network went out to the Internet. One of the biggest problems they had was trying to launch Google Earth. I had installed a little bandwidth tool on one of the laptops to get an idea of what type of bandwidth was required when the Google Earth application, with all of its default settings, fired up initially. And each one of those connections [the application initiated] was something like 800 kbps, so they had 20 laptops -- all at about 800 kbps at the same time -- and their Internet connection was only a T1, so they were completely saturating their connection to the Internet, just with this one classroom trying to launch Google Earth.

What is the most common mistake you see people make with wireless networks?

Just thinking they can solve any problem by adding more access points. It's a common misconception that if you have three or four, then five or six would be better. There are a lot of reasons why that's not true. It's not necessarily going to fix your problem, because the more APs you have, the larger your noise floor gets, and you have to start to adjust the transmit power of the access points. And if you have a lot of access points deployed, you may not be able to turn down the transmit power of the AP to make the noise floor low enough. Then you're just causing yourself more problems. It's like adding more speakers to a room so you can hear what's being transmitted -- it can be counterproductive.

What are some software tools you couldn't live without?

Whether you're using Ekahau, AirMagnet, MetaGeek or any of the other site survey tool, you need things that document the current signals that are in the air. You need tools to tell you if there's any kind of source of interference that might affect the RF frequencies because sometimes your sources of interference are not Wi-Fi devices. Cordless phones, Bluetooth, Xbox, WiMax -- there are lots of different things that can affect the unlicensed spectrum we use for wireless communications. Without having tools like that, you really have no idea what's going on. You're just licking your finger to figure out which way the wind is blowing.

How did you wind up working in IT?

I've always been the type of person who likes to figure out how things work and break complex things down into simple elements to figure out how they all connect to one another. I was working in a [clerical position at a] walk-in clinic, and it was a combination of that -- the troubleshooting inherent in my nature -- and this IT guy that came in with this big attitude like he had all this information that nobody else could handle. It was like he couldn't even explain anything because it was too much for him to even deign to explain something to me.

We were having our computers replaced. They were green-screen terminals, and we were getting a Windows-based machine in 1998. I didn't have a computer at home, so I think when he had changed the screen saver, I'd never seen anything be right-clicked before. And it sounds silly to say now, but at the time, it was like, ‘Whoa! What did you just do?' And he said, ‘Oh, I can't tell you that because some of the settings, if you changed them, you could crash the system.' Oh my God, please. I was thinking, ‘What does this guy know? What does this guy really need to know to do his job?' So I started researching it and found his job description, and I found out that you just had to have a certification -- so, he just passed this test? Are you kidding me? This is all you need to do to be in field support and do what this guy does? That attitude and me being put off by his not willing to educate me are what got me into night school. That was the catalyst.

How'd you get into networking?

When I was in night school, we were doing basic PC tech support. We started with MS-DOS and had to figure out how to troubleshoot printers. There was a rack of Cisco gear new to the school, and I didn't know what it was. It was just a bunch of interesting looking stuff with blinking lights and lots of cables, so I asked one of the people standing next to it what all this stuff was. I didn't know he was the teacher for this new course the school was offering. He was very nice and explained to me what all of the [routers and switches] did and what they were, and I said, ‘Huh, this looks really interesting.' I'd kind of had my fill of Microsoft and troubleshooting desktops, so the systems stuff seemed really interesting. Since I'd already had the class in MS-DOS, being in the command line wasn't intimidating.

The wireless I started to pick up when I was working at a theme park and they were expanding the wireless network. The senior [engineer] had had enough of running around the park putting up access points, so he said, ‘You could do it. If you have any questions, call me and I'll help you,' so I just took the project to the second level.

Looking outside of IT -- and within pop culture -- what's your guilty pleasure?

I'm just going to say The Mighty Boosh. That show is freaking hysterical. If people haven't seen it, they need to see it.

Next Steps

Using an RF site survey for wireless network implementations

Wireless interference: Frustrating or fun?

Tips for surveying and installing wireless networks

This was last published in February 2015

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