The Tour de Tulsa bike ride is about three weeks away. They have several rides between 10 and 100 miles. A couple of months ago I was thinking about doing the 48-mile half, but since I haven't been riding I might do the 22-mile instead. Also the shorter course rides out on Avery Drive, something I've never done. The ride is organized by the Tulsa Bicycle Club - http://www.tulsabicycleclub.com/tour_de_tulsa.php Communications is provided by the Tulsa Amateur Radio Club - http://w5ias.com/

As of a few months ago the Stillwater Amateur Radio Club VHF repeater on 145.35 requires a 107.2Hz PL tone. People from Missouri kept getting into it, I'd guess someone up there has a beam and a lot of power. Or maybe it's someone close by trying to get into the Missouri repeater and junking up Stillwater off a secondary lobe. For the 99.9% that aren't radio operators the PL tone is an audible sine wave at a frequency lower than normal speech. On a piano 107Hz is close to an A below low C - an octave below middle C. It's low but not as low as a 60Hz electrical hum. It's woofer but not subwoofer territory. Most human speech is between 300Hz and 3,000Hz so ham radios tend to filter out anything less with a 300Hz high-pass filter. But this filter is in the audio section - in the audio amp. The radio still transmits lower frequencies, the radios just make them effectively subaudible. So you can add these tones and program radios to make them do things. A repeater is a pair of radios, a receiver and transmitter. The receiver listens to a certain frequency and the transmitter retransmits whatever the receiver hears (but on a different frequency. It can be set up to retransmit everything, or to only transmit when it hears a specific frequency - the PL tone. If it's doing this it will ignore any signal that does not include the tone. So someone from Missouri can't accidentally have their signal retransmitted across Oklahoma.

I just read "Mapping the Incident - The Baldwin County ARES Location Finder", an article by Hal Reid, K6DPL, in QST Magazine October 2008. The article is about integrating a locally-hosted mapping/GIS application with local emergency services. That gave me this idea. Google should make their immense database of local information available to emergency services. Of course anyone can use it now, but pretty much only when you can connect to the Google servers.