Saturday, September 01, 2007

Radio Beacon

It's inevitably the most tangentially connected news peices that lead me to the most interesing and arcane radio tidbits. I read this on the CGC.

Fred Caughell of Bakersfield was issued a Citation for allegedly operating a Hamtronics R901 receiver which transmitted a weak but still illegal signal on a 406 MHz distress frequency. Distress frequency? It seems intuitive that Mariners would need specific distress frequencies, but Bakerfield is land locked if you hadn't noticed. Apparently we landlubbers also have distress frequencies. So it's here that we go to the books. Beginning in the early 20th century, the radio frequency of 500 kHz has been an international distress frequency for Morse code maritime communication. That we already knew. that's not even close to this frequency. It turns out thsi is not at all like a standard SOS.

The story turned out to be way more interesting than that. It turns out that 406 MHz is a frequency assigned for a satellite Emergency Position-Indicating Radio Beacon (EPIRB). These are used in the Global Maritime Distress Safety System (GMDSS) and designed to operate with the Cospas-Sarsat system. Who? Cospas-Sarsat is an international satellite-based search and rescue system, established by the USA, Canada, France, and the USSR way back in 1979. These automatic-activating EPIRBs, now required by international convention for many kinds of ships including commercial fishing vessels, and all passenger ships.

They transmit the signal to help rescuers located and identify a vessel from anywhere in the world. The newer devices incorporate GPS receivers making them even more accurate. More here, and here. The system clearly works as worldwide over 22,058 people have been rescued through use of the system.

COSPAS is a Russian acronym. "Cosmicheskaya Sistyema Poiska Avariynich Sudov", in English this translates to "Space System for the Search of Vessels in Distress". SARSAT is an acronym for Search And Rescue Satellite-Aided Tracking. More here.
So in short Fred wasn't really endangering anyone allegedly or otherwise. There are no sinking ships in Bakersfield, nor should his weak signal interfere with anyone that was. But the rules are the rules.