Watch out for Surveillance Cameras…Wireless Ones that Is

Posted by: Kenny Schiff on September 2, 2008

We’ve had several complaints over the last few weeks regarding the degradation of wireless voice quality at one of our hospital accounts.  What was perplexing about what we were hearing from users (and confirmed by our own people on site), is that the specific areas had previously not had problems.  Signal strength on Vocera badges seemed absolutely fine, and there was a nearby access point.

Last Thursday, I joined David, one of our network engineers to investigate further.  This post is for the benefit of those without wireless expertise.  For the engineers reading this post, what we found out will not surprise you at all.

Using Cognio (a spectrum analysis tool, now developed by Cisco) on his laptop, David quickly picked up a very constant signal in the 2.4 GHz band.  Cognio can sometimes be very specific about what it finds and told us that it detected an analog video camera.

Without getting into a very deep technical explanation, the 2.4 GHz band is home to not only WiFi devices (like Vocera), but Bluetooth headsets, microwave ovens, some consumer grade wireless phones, and yes, some consumer grade wireless video devices.

Laptop in hand, we went hunting.

As luck would have it, we soon ran into the hospital’s security director, whom we quickly quizzed about video cameras.  “No, we don’t have any IP or WiFi cameras,” he was quick to tell us.  We pressed him a bit more, mentioning that there are all kinds of consumer devices that use unregulated wireless that can interfere with a hospital’s wireless network.

He soon led us to the basement laundry room directly below the problem areas.

Raising his laptop above his head, David homed in on the source of the wireless interference.  The security director was soon back with a security products catalog in hand, showing us the type of camera and transmitter he was using.  In minutes, the consumer grade 2.4 GHz “video sender” device that he’d used to circumvent a hard wired installation was unplugged.  When we educated him a bit about the wireless interference he confessed that he had to move his transmitter pretty close to his receiver as the signal was not traveling well.  Our key customer contact also put two and two together, and mentioned that they’d been having issues with the wireless laptops as well.

And yes, back in the ED break room, with the video sender off, the Vocera genie sounded loud and clear.

A few lessons here…

  • Wireless network performance can and will vary based on the environment
  • If performance drops off and is consistently degraded, when it was once acceptable, unless your network configuration has changed, there’s a good chance that interference may be at play
  • In tracking down interference, don’t forget to look below you

P.S. Our customer contact just reminded me that I neglected to mention “the look of horror on the security director’s face when he discovered that his secret camera had been sniffed out!”

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