S.A.M.E. Decoding for Public Alerts Monitor - Electronic Circuits Projects Diagrams Free

DigiTan · 22nd August 2005, 12:00 AM

My parents recently got one of those weather alert radios with the siren that activates whenever the National Weather Services declares a storm warning. Since this usually happens before we know the storm is coming, I thought this was extremely useful. Also, the radio responds to other events like civil emergencies, 911 outtages, and every weather danger in the book.

The radio supports Specific Area Message Encoding, so I'm trying to come up with a decoder myself. Basically I want to pass these codes to an AVR so I can filter messages by urgency and reserve the alarm for certain times of day.

Everything is in the planning phase for now, so it basically this boils down to three questions:
1. Is S.A.M.E. the only protocol for public alerts, or are others in use?
2. Are S.A.M.E. decoders available in IC form?
3. If IC decoders don't exist, can someone show me a circuit for interfacing an LM567 Tone Decoder (or similar) to a typical 8-ohm speaker output? I'm not building a radio from scratch.[/url]

gerty · 22nd August 2005, 07:06 AM

The noaa website shows the SAME code , but do you know the specific frequency?. I'm in the Rescue Squad and carry a pager that monitors
155.1225 mhz , but it's not actvated until it "hears" a specific tone.
The frequency of that tone (audible) is in a Motorola code format such as
w41, some meaningless alphanumeric. Until you find the value of your specific code you really can't design for it. And if you find out to decode
it, I'd really like to hear about it.. Good luck

DigiTan · 22nd August 2005, 06:45 PM

For now, I'll just link this to the headset port of a regular WB radio where the stations operate in the 162.500-162.400MHz region.

Wikipedia is saying the data comes in the AFSK variety using 2083.3 and 1562.5Hz for binary, followed by a 1050Hz attention signal. I figure I can have three LM567 Tone Decoders on the speaker output, but I think this might require some automatic gain control for the LM567s. Once I get past this, the rest is pretty much digital.

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22nd August 2005, 12:00 AM	(permalink)
DigiTan	S.A.M.E. Decoding for Public Alerts Monitor My parents recently got one of those weather alert radios with the siren that activates whenever the National Weather Services declares a storm warning. Since this usually happens before we know the storm is coming, I thought this was extremely useful. Also, the radio responds to other events like civil emergencies, 911 outtages, and every weather danger in the book. The radio supports Specific Area Message Encoding, so I'm trying to come up with a decoder myself. Basically I want to pass these codes to an AVR so I can filter messages by urgency and reserve the alarm for certain times of day. Everything is in the planning phase for now, so it basically this boils down to three questions: 1. Is S.A.M.E. the only protocol for public alerts, or are others in use? 2. Are S.A.M.E. decoders available in IC form? 3. If IC decoders don't exist, can someone show me a circuit for interfacing an LM567 Tone Decoder (or similar) to a typical 8-ohm speaker output? I'm not building a radio from scratch.[/url] __________________ The most-hated young engineer in America. * AVR Projects * Robot War: TI * About

22nd August 2005, 07:06 AM	(permalink)
gerty	The noaa website shows the SAME code , but do you know the specific frequency?. I'm in the Rescue Squad and carry a pager that monitors 155.1225 mhz , but it's not actvated until it "hears" a specific tone. The frequency of that tone (audible) is in a Motorola code format such as w41, some meaningless alphanumeric. Until you find the value of your specific code you really can't design for it. And if you find out to decode it, I'd really like to hear about it.. Good luck __________________ gerty

22nd August 2005, 06:45 PM	(permalink)
DigiTan	For now, I'll just link this to the headset port of a regular WB radio where the stations operate in the 162.500-162.400MHz region. Wikipedia is saying the data comes in the AFSK variety using 2083.3 and 1562.5Hz for binary, followed by a 1050Hz attention signal. I figure I can have three LM567 Tone Decoders on the speaker output, but I think this might require some automatic gain control for the LM567s. Once I get past this, the rest is pretty much digital. __________________ The most-hated young engineer in America. * AVR Projects * Robot War: TI * About