Who said 5GHz was ‘clean’? :)

Here I am at home today being a good survey engineer and making sure all of my tools are in proper working order prior to going out and having to rely on them for the week when all of a sudden, I’m presented with the following anomaly when I’m exercising my trusty Spectrum Analyzer:

Those of you that are familiar with Spectrum Analysis in general usually expect to see something this bad (high duty cycle) in the 2.4GHz spectrum but not the mid-5GHz spectrum! Having just reloaded my laptop with Windows 7 and installed Service Pack 1, I was in the ‘let’s test it all’ mode to make sure nothing unexpected happens. At this point, I was pretty blindsided by the obnoxious noise happening and the ‘Generic – Fixed Frequency’ tag wasn’t helping me any. At a loss for what this could be since I live an acre away from my nearest neighbor and several miles from the nearest airport, I pinged a few of my friends. They suggested the usual suspects – MRI machine, TDWR, neighbors, etc all of which I explained away by location. Being that TDWR is in the 5470-5725 frequency, I changed my card over to 5.725 – 5.850 and after some time got this equally disturbing read:

At this point, I started to suspect my Spectrum Analyzer since I was using a non-Cisco branded Spectrum Analyzer card with the Cisco Spectrum Expert software (the card I was using had the Cognio components that Cisco purchased and re-branded as their own). So I grabbed a copy of the card manufacturers software to rule out in compatibility and I got the same results.

At the end of the day, I was able to swap in a Cisco branded SA card and my results normalized. Clearly I have a flakey (old) SA card that was giving me improper readings. Lessons learned:

  • Always test your tools and keep them in good working order
  • Don’t assume that your tools are telling you the truth. If you see something suspect, dig into it and validate against another source
Now I’m sure that I have a good card in hand I can go confidently into my week and knock this survey out of the park!
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New survey rig!

So, it’s been a bit since I’ve been out on a survey proper (not sure if that’s good or bad) and a while back I got some new components in for my rig. I was debating on retrofitting my trusty black Pelican 1510 case with new foam or getting a new one. Never one to spend needlessly, I trickle-down upgraded someone else with my old case and opted for a shiny new tan colored case – As far as I know, I’ll be the only one on our survey teams for the foreseeable future with a tan case so it should make it easier to tell mine apart. 🙂 So, a new Pelican case, a new battery for my Terrawave survey pack, a shiny new Cisco 1142, and some various other bits an pieces all get massaged into the pick-and-pluck foam of the kit. Revisiting the way I hang my AP during the survey was something I’ve been meaning to address for quite a while. I opted for the 2x 90 degree painter pole arms and a drywall finishing brush (sans bristles) and some good old fashioned drilling to assemble a pretty graceful looking mount:

The intermediary piece attached to the factory mount bracket is the brush head that I picked up from The Home Depot in their drywall finishing section:

Home Depot – Drywall Stippling Brush

After ripping out the bristles, a choice few holes later and my mount was ready! Next to place the battery and AP + mount in the bottom of the Pelican case and outline the pick-and-pluck:

Here is what the bottom of the Pelican looks like with the components nestled in – I coiled my CAT5 network cable around the mount and laid in the two 90 degree arms:

Add a top layer with some space for my spare laptop batteries, the AC adapter and some survey cards and call it just about done:

Now I’m off for a week of surveying!