Junkyard Dish Mount Tracks Weather Satellites

There’s a magnificent constellation of spacecraft in orbit around Earth right now, many sending useful data back down to the surface in the clear, ready to be exploited. Trouble is, it often takes specialized equipment that can be a real budget buster. But with a well-stocked scrap bin, a few strategic eBay purchases, and a little elbow grease, a powered azimuth-elevation satellite dish mount can become affordable.

The satellites of interest for [devnulling]’s efforts are NOAA’s Polar-orbiting Operational Environmental Satellites (POES), a system of low-Earth orbit weather birds. [devnulling] is particularly interested in direct reception of high-definition images from the satellites’ L-band downlink. The mount he came up with to track satellites during lengthy downloads is a tour de force of junkyard build skills.

The azimuth axis rotates on a rear wheel bearing from a Chevy, the elevation axis uses cheap pillow blocks, and the frame is welded from scrap angle iron and tubing. A NEMA-23 stepper with 15:1 gearhead rotates the azimuth while a 36″ linear actuator takes care of elevation. The mount has yet to be tested in the wind; we worry that sail area presented by the dish might cause problems. Here’s hoping the mount is as stout as it seems, and we’ll look forward to a follow-up.

It would work for us, but a 4-foot dish slewing around in the back yard might not be everyone’s taste in lawn appurtenances. If that’s you and you still want to get your weather data right from the source, try using an SDR dongle and chunk of wire.

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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.

Grab your own images from NOAA weather satellites

Can you believe that [hpux735] pulled this satellite weather image down from one of the National Oceanic and Atmospheric Administration’s weather satellites using home equipment? It turns out that they’ve got three weather satellites in low earth orbit that pass overhead a few times a day. If you’ve got some homebrew hardware and post processing chops you can grab your own images from these weather satellites.

The first step is data acquisition. [hpux735] used a software defined radio receiver that he built from a kit. This makes us think back to the software-radio project that [Jeri Ellsworth] built using an FPGA–could that be adapted for this purpose? But we digress. To record the incoming data a Mac program called DSP Radio was used. Once you do capture an audio sample, you’ll need something to turn it into an image. It just so happens there’s a program specifically for weather image decoding called WXtoImg, and another which runs under Linux called WXAPT. Throw in a little post processing, Robert’s your mother’s brother, and you’ve got the image seen above.

[Hpux735] mentioned that he’s working on a post about the antenna he built for the project and has future plans for an automated system where he’ll have a webpage that always shows the most current image. We’re looking forward hearing about that.