Friday, September 7, 2012

WRT54 Router Information Links

I've been doing more research into the WRT54 router hardware and thought I would share some links that I have found:

WikiDevi: Database of thousands of wireless adapters, embedded systems, images, information, etc.

Copy of the IEEE specification 802.11-2007
Yes, I know it's outdated but for research on things like frequency stability, it does me just fine.

Making 802.11G Transmitter Measurements, whitepaper by Agilent

Search the FCCID database for any pertinant test data (use the FCCID found on the bottom of the routers): 

HSMM-MESH at the Pigman Triathlon 2012

The Pigman Triathlon long course is a half Ironman race, consisting of participants completing a 1.2 mile swim, 56 mile bike ride and a 13 mile run.  For many years, they have asked the Cedar Valley Amateur Radio Club to provide communications between the race officials, water stops, Sheriff departments and keep an overall watchful eye out for participants that need medical attention.

We traditionally run two net control locations, one dedicated to in-park portions and the running course and one about 3/4 mile away handling the bicycle portion of the race.  During the race this year, we decided to try a couple of new things, adding a HSMM-MESHÔ link between the two net control stations to use an IRC text chat and share APRSÔ data between the two spots.

On a scouting trip prior to the event, we found there was not line of site between the two shelter locations so we decided to set a node in the Gazebo's parking lot, which did have line-of-site to the North Shelter location.
Google Earth view of locations
When I got all the equipment set up the morning of the race, I was surprised on the robustness of the link.  100% link quality to both the gazebo parking lot and to the gazebo router (going through a few trees).  As soon as the router that had the IRC Chat server installed (at the North Shelter) was powered up, both computers connected to the server and never dropped out throughout the entire 8 hours.  We used the IRC server to share participant numbers for leads, sags, etc.  Simultaneously, we used an APRSÔ client, APRSIS32, with cached maps to track our chase vehicle following the last bike rider throughout the course.

Unfortunately as one of the NCS stations, I did not have enough time to test everything I would have liked (playing with output powers, recording data, antenna positioning) but as a first deployment of HSMM-MESHÔ, I would call it a success.

Antenna at North Shelter
Lessons learned:

  • Antenna height can make or break your link.  During the prior testing, the panel antenna at the North Shelter was not high enough, causing a bad link.  Elevating it the day of the race solved all those issues.
  • Having a deployment kit with everything needed makes setup a breeze (I came away with several ideas from this event, look for a couple of "go-kits" detailed here soon.
  • Don't rely on computers having the necessary software loaded.  Always bring a flash drive with the software you'll be using, just in case you are not using your own computer.
  • You really need to dedicate an operator to oversee 'special' tasks during a deployment (APRSÔ, HSMM-MESHÔ, etc) which leaves the other operators to focus on their jobs.
Equipment used:
  • Gazebo at entrance to park
    • WRT54GS router, modified for Part97 operation
    • One 5.2dBi omni-directional antenna (Cushcraft S2403B) bungee corded to gazebo
    • 3dBi antenna on other port
    • 19dBm output
  • Gazebo parking lot (had line of sight to north shelter)
    • WRT54GS router, modified for Part97 operation mounted on tripod
    • 12dBi omnidirectional antenna on tripod (~5' elevation to base of antenna)
    • 3dBi antenna on other second port
    • Belkin residential Gateway power supply
    • 19dBm output
  • North Shelter (0.75 miles distance from Gazebo)
    • WRT54GS router, modified for Part97 operation
    • 19dBi patch antenna (Tranzeo TR-CPQ-19), router mounted inside antenna enclosure
    • 9ft tripod stand (American DJ LTS-6)
    • 19dBm output
Future Ideas:
  • We've already talked about using a couple of cameras set up along a particularly crowded portion of the course inside the park, monitoring them on a computer screen
  • Now that we have proven it will work, possibly set up an APRSÔ display tracking first/last participants at the race official's table