The whole image covered the entire east coast USA. I cropped the usable piece out. The raw image looks like white clouds on a gray background. Processing software inserts land and water coloration and state borders and precipitation probability.
Ok, Here is more info about receiving weather satellite images…
What you need (for NOAA APT and Meteor LRPT sats):
1. a radio that can receive in the area of 137 to 138 MHZ
2. a suitable antenna, tuned for that band
3. some way to capture the audio
4. some software that converts the captured audio to an image.
Oh and you’ll need to somehow get satellite tracking information
But in my case specifically I’ve gotten and done this:
1. got an RTL-SDR Blog V3 sdr radio (already had one for short wave listening). This is a USB device, you hook an antenna to it, and hook it to a usb port, you can use the suite of software in the rtl_sdr linux package to do basic radio listenning
2. Well I’ve been in the antenna hacking stage, right now I have it hooked up to a dipole antenna of mine that just happens to have low SWR in the area of 137.5MHZ. But ever hating fussing with antenna construction, I ordered what’s called a V-Dipole built just for NOAA weather sat reception. So a V-Dipole is just a dipole but the two elements in this case are set at an angle of 120 degrees to each other, rather than having them in a straight line. By doing this it basically get omnidirectional reception and also reception from UP, where the sats are. The actual antenna to use for this is a helical antenna built for the weather sat band, Unfortunately I cant’t find clear instructions online to build, and I see no one selling one, I did see at a legit ham radio store site, that you could pay $300 for a built one for another band. Uhm… No.
3. and 4. To capture the audio and process it I am using Raspberry-NOAA-V2, findable on Github. basically you devote a raspberry pi 2 or greater to have a fresh OS install, and install that software, It does the full job of tracking sats, and listening at the right time, and converts the audio to sat images with various “enhancements”.
NOAA sats, NOAA 15, 18 and 19, are in a polar orbit, sun synchronous , meaning they fly pole to pole, with a period of about 90 minutes, and they keep themselves aligned with the sun, so that their images always have the same lighting on the day side. They don’t have a normal camera in them, they have more or less a single line Earth scanner in them… so as they fly they are scanning a line of the earth perpendicular to their path, and they put out about 2 scan lines a second. The signal is analog, AM modulated on a 2400hz carrier, the whole shebang is FM modulated somewhere in the 137mhz band, a different channel for each sat. The Meteor sat is a Russian sat that uses a digital encoding, but it’s the same basic scanning idea, just a different scan line encoding.
You don’t really need to know all that, you use software to decode the signals, and generally you can expect NOAA images to be like old time TV, sometimes a clear signal, sometimes snowy. And the Meteor, being digital, will be clear, but with black lines where the decoder failed to hear a decent signal.
Well, Raspberry NOAA V2 (RN2), is a great package that just handles everything for you to track, record and decode the 3 NOAA sats and a Meteor sat. I’m running mine on a headless RPi 4, with minimal OS (no GUI). RN2 runs a web server on the pi so you can check schedules and look at captured images.
Well we have to talk about the Meteor M2 saga.. It seems that Meteor M2, was giving great results — looking back at other people’s posts and videos about it, but it has failed… and it’s replacement ? Failed. So now we’re up to the newly launched Meteor N2-3. Support for that sat in RN2 is in beta development. I took a peek at that code, and found that, yes, once it is released I can expect amazing sat photographs from it.
And we should talk about the realities of antennas and Raspberry PIs….
I have played with radios since I was in grade school. Always putting a lot of energy into the question — why is my reception so bad? I have played with antennas and long ago came to the conclusion that they are magic, and a kind of magic I can’t grasp. Sure there are formulas, and calculators, and simulators all for designing the perfect antenna, but when it comes down to it, you never have the perfect antenna, and you never have the perfect antenna installation.
So these few days have been spent fussing with antennas. And as I said.. I ordered one, and hope it does it’s magic, but in the mean time, this above is the best image I got so far, and it was done with a hacked together v-dipole from an old TV rabbit ears, at ground level (Some say go as high as possible, some say no.. it needs to be between .4 and .6 meters off the ground.)
Mind you… as far as antennas and SDR and RPi’s go… the PI itself is a noise source. USB is a noise source… so I have two chokes on the USB cable to the SDR dongle, I have a choke on the power going in to the PI, and I have everything stretched out so the SDR dongle is as far from the PI as possible, and the antenna is as far as possible away.
Earlier today, I used my 40M OCF Dipole, (installed in my garage):
So you can see my motivation… that image says I have the potential to get images from the gulf of mexico up to way north in canada…
My next steps: Once the actual antenna comes in, install it properly. Also I have a 137mhz band pass filter on order. Also have a much better radio on order. Ultimately this is all going into a waterproof box in my garden. I had put together a 12v battery, a solar panel and a charge controller, for a past experiment… Now it will be re-purposed as the beginning of my garden weather station.
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