Fail of the Week: Tracking Meteors with Weather Radio

It’s not hard to detect meteors: go outside on a clear night in a dark place and you’re bound to see one eventually. But visible light detection is limiting, and knowing that meteors leave a trail of ions means radio detection is possible. That’s what’s behind this attempt to map meteor trails using broadcast signals, which so far hasn’t yielded great results.

Passing jet’s Doppler signature

The fact that meteor trails reflect radio signals is well-known; hams use “meteor bounce” to make long-distance contacts all the time. And using commercial FM broadcast signals to map meteor activity isn’t new, either — we’ve covered the “forward scattering” technique before. The technique requires tuning into a frequency used by a distant station but not a local one and waiting for a passing meteor to bounce the distant signal back to your SDR dongle. Capturing the waterfall display for later analysis should show characteristic patterns and give you an idea of where and when the meteor passed.

[Dave Venne] is an amateur astronomer who turns his eyes and ears to the heavens just to see what he can find. [Dave]’s problem is that the commercial FM band in the Minneapolis area that he calls home is crowded, to say the least. He hit upon the idea of using the National Weather Service weather radio broadcasts at around 160 MHz as a substitute. Sadly, all he managed to capture were passing airplanes with their characteristic Doppler shift; pretty cool in its own right, but not the desired result.

The comments in the RTL-SDR.com post on [Dave]’s attempt had a few ideas on where this went wrong and how to improve it, including the intriguing idea of using 60-meter ham band propagation beacons. Now it’s Hackaday’s turn: any ideas on how to fix [Dave]’s problem? Sound off in the comments below.

Better Tornado Warnings with Polygons and Pi

Everyone pays close attention to the weather, but for those who live where tornadoes are prevalent, watching the sky can be a matter of life and death. When the difference between making it to a shelter or getting caught in the open can be a matter of seconds, it might make sense to build an internet enabled Raspberry Pi weather alert system.

We know what you’re thinking – why not just buy an off-the-shelf weather alert radio with Specific Area Message Encoding (SAME) reporting, or just rely on a smartphone app? As [Jim Scarborough] explains, living in the heart of Tornado Alley and having had a brush with tragedy as a kid teaches you not to be complacent with severe weather. He found a problem with the SAME system: lack of locational granularity below the county level, leading to a tendency to over-warn during tornado season. [Jim]’s build seeks to improve SAME by integrating National Weather Service polygon warnings, which define an area likely to see a severe weather event as a collection of geographic vertices rather than a political unit. He’s using a Raspberry Pi NOAA weather radio receiver with SAME decoding, and while details are sparse and the project is ongoing, the idea seems to be to use the Pi to scrape the NWS site for polygon data once a county-level warning is issued.

It’s an interesting idea, and one we’ll be keeping an eye on as [Jim] continues his build. In the meantime, you can brush up on weather radio and SAME encoding with this Arduino SAME decoder.

[via r/weather]

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.