Listening to weather satellites with random junk files

Listening to weather satellites with random junk files

HomesaveitforpartsListening to weather satellites with random junk files
Listening to weather satellites with random junk files
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Listening to NOAA weather satellites as they pass overhead is relatively simple! All you need are a few pieces of wire and a basic radio. In fact, decoding the images from the transmissions took a bit more effort, as I learned during the process of making this video. Below are some of the resources and guides I found helpful for this project:

Basic introduction to satellite reception: https://publiclab.org/notes/sashae/06-26-2020/diy-satellite-ground-station

The antenna model I used: https://lna4all.blogspot.com/2017/02/diy-137-mhz-wx-sat-v-dipole-antenna.html

Website to track satellites and determine upcoming air passes (early 2021, those to watch are NOAA 18, 19 and 15): https://www.n2yo.com/

Info on the NanoVNA that I used for antenna adjustment: https://www.youtube.com/watch?v=QJYeFpiqY8c

This is a decent software defined radio, capable of hearing these satellites. You can get them with or without many extras like antennas and amplifiers: https://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/

The software I used to interface with the SDR and record audio files (for Linux / Raspberry Pi): https://gqrx.dk/
(I heard that SDR number is good for Windows, but I haven't tried it: https://airspy.com/download/)

The software I used to decode the images: https://wxtoimgrestored.xyz/

Some "pitfalls" I encountered when working with recorded audio files (not always obvious in online guides):

-WXtoIMG is old abandonware and barely works on modern computers. The Linux version has display issues and crashes when trying to update Keplers, at least on my system. On Windows, I found that the beta version works better, the "stable/" version does not install at all). It also doesn't like modern audio drivers, so if you can't decode live signals, you may need to record and decode later (see below for even more tips on this!)

-Gqrx saves recordings in stereo with wrong sample rate. You will need to open the recorded audio file in Audacity (or another audio editor), reduce the file to mono, and change the sample rate to 11025. You will probably also want to normalize the file after each step. See here for more details: https://lucasteske.dev/2016/02/recording-noaa-apt-signals-with-gqrx-and-rtl-sdr-on-linux/

-WXtoIMG It is very picky about timestamps and you may have to fiddle a lot to get your recording to match a known satellite pass. I've had no luck using the filename to specify the recording duration as the FAQ recommends. I had to download a file attribute editor (or this software can change timestamps: https://noaa-apt.mbernardi.com.ar/). You need to replace the /"Modified/" date and time (not the /"created/" attribute) with the time the recording started (because once you process the file through Audacity, timestamp will be different). I then had to manually adjust the map overlay in WXtoIMG (luckily I had a visible reference point, if it's all clouds you might be out of luck!) See https://wxtoimgrestored.xyz/faq/ for some information on this.

I hope this all helps! There are many guides online explaining how to do this, some are more comprehensive than others. There are probably also a lot of videos that explain this better than mine, I was just trying everything for the first time.

Please take the opportunity to connect and share this video with your friends and family if you find it useful.