John, The new digital system is the one on 406 MHz. Already operational and available (for a significant price) for your boat. They can triangulate on your location much faster than the old analog alarms on 121.5 MHz, plus the signal is encoded with information telling them who you are and other such useful information, once they look it up in a central database.
I doubt we'll be upgrading our club's planes until we're forced to. The 406 MHz ELTs are expensive and don't make the plane fly any better. Tailwinds and clear skys... Ghery From: [email protected] [mailto:[email protected]] On Behalf Of jshinn Sent: Wednesday, November 03, 2004 4:34 PM To: 'POWELL, DOUG'; 'David Heald'; [email protected] Subject: RE: The TV That Sent Out a Cry for Help, via Satellite The Air Force has little, if anything to do with 121.5 MHz. That is a civilian guard frequency. The Military version is 243 MHz. Twice civilian frequency. The military will monitor both frequencies while civilian / commercial establishments will monitor 121.5 MHz. It appears that you have copied the specification from some ELT. However, there is no specific modulation required. Just coming up on the frequency with a carrier will set off alarms. Voice (am) stating "Mayday" or "PAN-PAN" will definitely wake someone up. I am not sure what you mean about the "new digital system", but I am not going the change the ELT in my plane. It will stay analog for the foreseeable future. John Shinn From: [email protected] [mailto:[email protected]] On Behalf Of POWELL, DOUG Sent: Monday, November 01, 2004 7:58 AM To: David Heald; [email protected] Subject: RE: The TV That Sent Out a Cry for Help, via Satellite I saw this bit of news cross my desk a couple of weeks ago. I think Paul Harvey reported it as well. At first I thought it was rather funny but after further consideration I realized this was something that can happen to us all. So, I decided to check into 121.5MHz distress signal. As I expected it is an analog signal but it has a very specific modulation. The new digital signal system should help considerably and inadvertent transmissions like this may only be interference. But my question is how a TV was able to produce the specific modulation required for a distress signal. Here are the specs: of the 121.5 MHz beacon RF Signal Transmitted Power: 50 - 100 mW PERP Transmission life: 48 hours Frequency: 121.5 MHz +/- 6 kHz Polarization: Linear Modulation Sweep rate: 2 - 4 Hz Range: 300-1600 Hz (swept at least 700 Hz) Modulation type: AM Modulation depth: > 85% Duty Cycle: 40% Source: http://www.cospas-sarsat.org/Beacons/121Bcns.htm My suspicion is that the Air Force considers any emission at that frequency as a possible distress, given the fact that a crash can also damage a transmitter. Does anyone know what is SOP in a situation where a transmitter is simply emitting a CW signal on that frequency? Oh, and by the way, who would be the governing authority to assess the $10,000 daily fine? Regards to all and may your favorite candidate win the election, -doug From: [email protected] [mailto:[email protected]] On Behalf Of David Heald Sent: Monday, November 01, 2004 7:41 AM To: [email protected] Subject: The TV That Sent Out a Cry for Help, via Satellite Fresh from today's New York Times - our favorite Oregonian emergency locator tv... :) The TV That Sent Out a Cry for Help, via Satellite By TOM ZELLER Jr. Pizza ovens, jumbo score boards, Christmas lights and other appliances have issued emergency distress signals and brought search and rescue teams running. http://www.nytimes.com/2004/11/01/technology/01signal.html?th Have a great week, -Dave David Heald EMC Engineer / Worldwide Regulatory Symbol Technologies tel: +1.631.738.5373 fax: +1.631.738.3915 Symbol. The Enterprise Mobility Company. (TM) ________________________________________________________________________ This email has been scanned for computer viruses. 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