[Josh] has a series called Ham Radio Crash Course and a recent installment covers how you can grab satellite images directly from weather satellites. This used to be more of a production than it is now thanks to software defined radio (SDR). Josh also has another project using a 3D printer to make an antenna suitable for the job. You can see the video below.
The software is the venerable WXtoImg program. This is abandonware, but the community has kept the software available. The program works on Linux, Windows, and Mac. The satellites in question operate around 137 MHz, but that’s easily in the range of even the cheap SDR dongles. [Josh] shows how to use a virtual audio cable on Windows to connect the output of the radio to the input of the WXtoImg program. Under Linux, you can do this with Pulse or Jack very easily without any extra hardware.
There’s some setup and calibration necessary for the software. You’ll also need the current orbital data and the program will tell you when you can find the next satellite passing overhead. Generally speaking you’ll want your antenna outside, which [Josh] solved by taking everything outdoors and having some lunch during the pass. It also takes some time to post-process the data into images and audio.
We know this isn’t new. But we did like [Josh’s] clear and up-to-date guide. We remember watching NOAA 15 as it started to lose its electronic mind.
Keep meaning to figure this out with a coathanger turnstile antenna and a Radioshack Patrolman with input to a soundcard.
No, it was never that difficult.
CQ magazine had a story in the sixties about a ham in England who received photos from a weather satellite. It was novel then (and so were weather satellites) and some company involved even paid for a trip for the ham to the US so he could explain his setup, and for him to see some background of their ooeration.
137MHz wasn’t esoteric in the sixties, just not common since there wasn’t much to hear before satellites. But many a ham had built 144MHz converters, including using more expensive low noise tubes, the 416 and 417, or the Nuvistor, which gave low noise with less fussing.
Pop ular Electronics ran a converter article in the early sixties to receive a satellite, though I guess that was 108MHz, not 137. But not much difference, and thus not beyond many a builder.
It got easier in the seventies, lots of articles and 3 even published a book about receiving weather satellites. Lots of hardware, use a converted two way radio receiver strip converted from 150MHz to 137. Or use a scanner receiver that were becoming common and solid state.
One issue was that wearther satellite deviation was a bit wider, and with doppler shift, the narrow deviation receivers were a tad too narrow. One article just used a wider filter.
So people built their interface, using an oscilloscope for display, or building from scratch. I think some used surplus fax machines. It wasn’t too complicated, and done before home computers became common.
And antennas were never comoicated, made with metal scrap, no 3D printer needed (or available at the time).
Lots had the requirements needed
Would love to see using a FAX machine as output for display!
How close are the protocols to telephonic fax??? Be cool if you could stick an arduino in an old external fax modem, tape it to a handheld radio that has a wide enough “weather/hi-VHF” band (Whether you need to SSB mod it or not) and stick a dot matrix on top, make an antenna that goes up like an umbrella and have a portable-ish weather station for off grid camping/overlanding/boating.
I was talking about fax machines that were surplus in the seventies. If I recall properly, they coukd be used to print SSTV pictures with tge right audio decoder, and a tiny modification.
I assume the consumer FAX machines that came later were different, and whike less mechanical, more complicated otherwise.
Now that everyone has computers, that’s likely the easiest route, and display on the screen, or print to a standard printer.
I think I mentioned it before, but in the seventies or early eighties Ralph Taggart put together a book “Weather Satellite Handbook” that accumulated his articles in 73 on the topic. I saw it digitized a few months ago, I think at archive.org. There were one or two later editions, published by the ARRL.
Maybe the most concentrated source on the topic.
I had a surplus Western Union Desk Fax back in the 70s. Big green monster with a hard-to-find acorn bulb as a light source and took electrolytic paper.
What I was getting from a brief description in an old “Satellite Experimenters Handbook” that it was really only the mechanisms that were employed to raster print line scan values derived on the fly…. and it could otherwise be done on CRT or sampled digitally.
“It wasn’t too complicated”
Really??? I was around back then and VERY FEW folks could
decode these signals. It took me weeks of building and finding
parts to do it(and that was in the 80’s)
Yes….back then…it WAS COMPLICATED !!
“It wasn’t too complicated”
More thoughts on that comment.
Only someone who has grown up in the
“point and click” era -AND/OR- had access to a university
full of parts and equipment would say that.
in A way your statement about it been not new is correct but there are always new people coming into the hobby and to receive a weather sat directly with a pile of bits on your workbench is cool even if it’s just to have a play with. There is lots to learn, Doppler shift, modding a rig to broaden its IF to capture the signal interfacing to a computer calibrating etc. building the antenna, learning about tracking satellites and keplarian elements.
this used to be my job (repairing such things), seemed really easy when i had all the proper gear.
No 3D printer needed. Once I got the RTL-SDR dongle from Amazon over night, it took about 4 hours get it done and that included going to home depot to get some copper tubing to make a QFH antenna and actually making it. Had I opted for a V antenna with a wire coat hanger it would have taken about 45 minutes. But due to things on the way I decided to go for the QFH mounted on the roof (the old analog TV antenna was finally taken down to make room for the QFH). The software part took about 1/2 hour to get done.
https://www.instructables.com/id/Raspberry-Pi-NOAA-Weather-Satellite-Receiver/
Sligtly more complex setup if you want to load stuff up to an amazon server can be found here,
https://nootropicdesign.com/projectlab/2019/11/08/weather-satellite-ground-station/
And the instruction for making the QFH antenna with bill of materials is here: http://tinhatranch.com/how-to-build-a-qfh-quadrifilar-helix-antenna-to-download-images-from-weather-satellites/#.XktXE9-YWkA
Yes, it was those Western Union fax machines that hit the surplus market, various articles about them. QST for May 1972 is an article that comes to mind, but I can’t verify the date, it just popped into my.mind.
Hmmm, checking some offline materials, that say cheap and nasty PB/Weather/Air/Marine/Police/VHF-Hi whatever they wanna call coverage in the 108-175 area receivers often work better than “nice” communication receivers because you ideally want 50khz IF bandwidth to allow for some doppler shift, and the cheapy ones have a round shouldered 30khz IF that lets in the edges, and spendy ones have a tight sharp 30khz only (Unless modified or intended to have wide or switchable IF)
Also, found lots to play with here… https://www.dxzone.com/catalog/Software/Weather_and_FAX/
I’ll second that link — lots of fun stuff to do with a shortwave radio and decent dipole with weather fax/radiofax/hf-fax. The US Coast Guard, among others, still transmits some interesting stuff.