Decoding NOAA weather radio with an Arduino

The National Oceanic and Atmospheric Administration is responsible for broadcasting the signals used in weather radios. They use a protocol called Specific Area Message Encoding (SAME) and [Ray Dees] recently published an Arduino library that lets you decode the SAME message packets.

He doesn’t provide a method of tuning the radio signal, but at first you can use the audio samples he points to. The actual broadcasts happen on one of seven frequencies between 162.400 MHz and 162.550 MHz but the tones are also broadcast on TV and Radio alerts. Once you have the audio it is fed into a pair of XR-2211 Tone decoders. This provides just three interface pins for the Arduino to watch.

The annoying noise that grabs your attention at the beginning of a weather alert, or test of the alert system is actually what the SAME data packets sound like. From those tones this system will be able to decode what type of alert is being issued, and the geographic locations it affects. If you interested in more info about SAME head over to the Wikipedia article on the topic.

Comments

  1. Cheshire says:

    I have used an ezcap668 dongle that uses an RTL2832U cand an elonics4999 tuner chio to eneble a software radio mode that can receive the weather satellite broadcasts at 137 MHz, its fairly easy with the right antenna. One easy antenna for receiving satellites is the so called infinite balun spiral antenna, Which uses an archimedes spiral made out of coax, its quite cheap.

  2. Aussietech says:

    Yes, this simple PLL lock/unlock detector using one side of the FSK will work, but with only a slightly more refined demodulator that uses both sides of the FSK (e.g. wide lock and a floating voltage slicer on the VCO control signal; see ham RTTY) the noise immunity is greatly improved and produces a much cleaner image.

    A “turnstile” crossed dipole antenna is also quite effective for receiving satellite signals.

  3. Cheshire says:

    I’m sorry, it appears I misread the article and gathered the mistaken impression you were trying to receive satellite broadcasts. It appears you were actually talking about the 162 MHz NOAA weather broadcasts. There – instead of a relatively complicated spiral or turnstile antenna, you could use (almost) any vertical antenna, even one that is not designed for the frequency.

  4. rdsman says:

    The portion shown detects the 1050 Hz Warning Alert Tone, not the AFSK.

  5. Rick says:

    New board for NOAA Weather Radio and SAME message decoding.
    http://www.aiwindustries.com

  6. Dave Risik says:

    I’m new to this IC, what is the input and the output? I need to interface this with a Motorola Alert Monitor ? That is, I’m using this to replace the Vibrasponder on the tone decoder board… Thanks

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