16 December 2017

Amateur Radio Repeaters in Georgia

When I'm not playing radio I'm making maps for a living (yes Virginia, you can make a living making maps). Most of the maps are very esoteric and tightly tied to the needs of people who do things like inventory utilities or inspect retail operations. But every so often I get to indulge myself and put together a map that is fun to work on, presents a challenge and provides what I hope is real value to folks who share my interests.

Earlier this year, as the spring storm season approached, I put together a web map that depicted all the Amateur Radio repeaters in the State of Georgia. The map is built using a system called ArcGIS Online, a service provided by ESRI, and is hosted in ESRI's cloud environment.

Compiling this map presented some interesting challenges, the biggest being the collection and aggregation of location information for the repeaters. At first I thought it would be an easy task to just go to the FCC's radio license database (ULS), do a search on Amateur service repeaters in Georgia, download the data, geocode it and publish it. Simple, straightforward, easy. Hah! Silly me. The FCC either doesn't have, or doesn't make public, Amateur radio repeater information.

To throw together the repeater information I went out to multiple on-line sources that held the bits and pieces I was looking for - regular repeater data from this source, digital repeater data from that source, and some 'insider knowledge' of the actual locations of repeaters near me. It was an inexact, tedious and error prone process, but I wanted to get it done so I had something to use and share with the local Amateur radio community. The map was completed and published, but I knew there were a lot of problems with the repeater data.

Amateur Radio Repeaters in Georgia

Fast forward to a few weeks ago and I figured it was time to try to update the repeater listings in the  map and present complete and authoritative information on each repeater. With accurate repeater locations you can do lots of interesting things like line-of-sight analysis, terrain masking studies, RF coverage polygons, and more. This has the potential to help visualize the repeater infrastructure in Georgia in entirely new ways.

After some emails and phone calls I found out that the actual repeater locations (and all other information about the repeaters) are held by the  Southeastern Repeater Association (SERA). SERA is the recognized repeater coordination group for the southeastern US. The term 'coordination' refers to the process of having a regional coordinating organization like SERA assign a frequency pair (input/output) and PL tone to your repeater. If a repeater is coordinated then it assures that the repeater will not cause interference with other repeaters in the region (and vice-versa) and that the FCC will resolve any interference issues between a coordinated and uncoordinated repeater in favor of the coordinated repeater. Repeater coordination in places like the Atlanta metro area is absolutely essential to keep the repeaters from stepping all over each other. In fact, I've been told that there are so many Amateur radio repeaters in the Atlanta area that there are no more 2 meter frequency pairs available above a line that runs from Columbus to Macon. That's a LOT of repeaters! If you live in the Atlanta area or are visiting you can be assured of finding at least one (and usually several) repeaters that you can hit with just a handheld radio. The fact that these repeaters are not stepping all over each other and causing interference is due to the hard efforts of SERA.

SERA considers the locations of its coordinated repeaters to be proprietary information. Part of the issue is security - a lot of repeater owners are uncomfortable with the idea of their repeater/tower locations being made public. The other issue is that SERA makes a small profit by selling repeater guides and journals that contain this proprietary information. Since SERA is a non-profit organization they see this as a way to help cover their operating costs. I can understand and respect that.

So this has me facing my original challenge - how to collect accurate repeater data? I still have the old method to fall back on - scrape the data out of a number of different sites on the web that hold the data and do not put any restrictions on its use. However, I'd also like to take this opportunity to invite individual repeater owners/trustees to review their repeater data in this web map and provide me any necessary updates or corrections. I'll respect your wishes and show only the data you want displayed.

If you are a repeater owner or trustee and would like to help keep this data up-to-date please contact me at w8byh@arrl.net.



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