Disappointing change of plans in wireless VoIP research

October 10, 2007

It was time for our first site survey--a 'reality check' for a proposed site. Radio Mobile's altitude data is around 90 meters in resolution, so trees, buildings, and even small hills don't show up. Google Earth can help some, especially if people have posted geotagged photos, but a site survey is still a requirement.

My goals for the site survey were to

  • verify line of site (visually)
  • verify physical access (road/path conditions, permission to be there, etc.)
  • identify a precise location, with GPS coordinates
  • identify how to mount the antenna(s) (check ground consistency, places for guy wires, etc.)
  • check communications (in our case, cell phone coverage)
  • take photos of the area for reference
  • check for possible sources of RF interference

Below is a list I've compiled of what I would like to have on future survey trips. Needless to say, I was not able to bring all of these items on our first trip. I hadn't even purchased all of them yet.

  • printed driving directions
  • GPS with waypoints for all proposed sites
  • compass
  • camera
  • cell phone and/or 2-way radio
  • phone book
  • binoculars
  • azimuth and compass bearing of all 'neighbor' nodes; be sure to compensate for declination
  • drinking water
  • hiking boots (for mud if nothing else)
  • spectrum analyzer
  • laptop (Radio Mobile, spectrum analyzer)

We headed off towards node 12. Google Earth directions are not so accurate on tiny roads, as it turns out. I guess this shouldn't be a surprise. We ended up on many private driveways, and were even told at one point that we had probably "activated a neighborhood watch", whatever that means. We drove around in a few circles, and finally gave up on that route. As far as we could tell, the hill in question was private property. We had what we think was the owner's name and may have been able to get permission to do our testing there, but the bigger problem was that there was no usable road from where we were to the top of the hill, despite what Google Earth said. We could have walked there with a compass, GPS, and camera, but not with large antennas, batteries, etc.

I was surprised to learn that Google Maps directions are sometimes entirely different than Google Earth. Google Maps seemed to avoid the very little roads all together. Having given up on approaching the hill from the south, we followed the Google Maps directions. These led us all the way round the base of the hill and we ended up east of where we wanted to be, and significantly lower. We could look up and see our goal, but there was no way we could reasonably carry all of the equipment up that slope.

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