vhfwxsatellitetips
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+ | //Meteor-M2 LRPT capture of the Eastern Atlantic and the U.K. & Ireland - MM3IIG// | ||
- | This is the first draft of what will hopefully become | + | **Update: 24/08/21** - We’re running |
- | VHF satellite work is the easiest | + | This is the home of what will hopefully become a useful club resource for people wanting to do some VHF satellite reception |
- | ---- | + | VHF satellite work is the easiest satellite reception work to get into. If you get the bug after doing this consider moving up to L-band HRPT reception, which should doable with a modest antenna. The next step up from that is to geostationary satellites, where you'll be needing dishes, amplifiers, filters, and a whole lot of kit. There are a few places on the internet that specialise in this kind of thing. |
- | * [[vhfwxsatellitetips-antenna|Antenna considerations + links to projects]] | + | To-do: Finish the antenna |
- | * [[vhfwxsatellitetips-hw|Extra Hardware]] | + | |
- | ---- | + | Mark MM3IIG |
- | + | ||
- | ====== Software overview + tips ====== | + | |
- | + | ||
- | ===== SDR Receiver software ===== | + | |
- | + | ||
- | Honestly, it doesn’t really matter what software you use as long as it can pipe out audio to a virtual cable or record the audio or baseband for use later (for APT be sure to resample recordings to 11,025 kHz with your software of choice - see below). For LRPT you may wish to use SDR# as the plugin and setup is well-supported, | + | |
- | + | ||
- | If you’re struggling for CPU clock cycles you can run with a low sample rate for this work. This is useful for RTL-SDR dongles. Both signals easily fit into a 250kbps sample rate. This also makes it doable on RPIs, but processing the data afterwards can take longer than other devices. | + | |
- | + | ||
- | Here's the most cited/ | + | |
- | + | ||
- | For APT there' | + | |
- | + | ||
- | ===== Demodulation, | + | |
- | + | ||
- | ==== WxtoImg ==== | + | |
- | + | ||
- | **Overriding pass auto-recording** - you may need to tell WxtoImg to stop enabling recording when you’re trying to do other work in it. The best way to do this seems to be to deactivate the specific satellite the software is trying to record next from the list of satellites in the options - or untick them all. You may also need to do this to record one particular satellite if two passes are happening at the same time. | + | |
- | + | ||
- | **Composite tips** - make sure that you make any changes to an image individually before saving | + | |
- | + | ||
- | **Animations** - it works, but it’s ropey, depending on the AVI format you choose. It may be better to transcode to MP4 afterwards if you want to do anything with it. Same tips here as for composites: make changes to each image individually! Another tip is to scale the timing/ | + | |
- | + | ||
- | **Desyncs/ | + | |
- | + | ||
- | **Importing audio files tip** - If you are bringing any audio file back into WxtoImg you will need to clone the timestamp from the original recording! If you don’t you may find your map overlays don’t work right. Again, NOAA-APT has a function for this in the Tools menu. | + | |
- | + | ||
- | **Recording passes for longer** - If you improve your antenna’s low-angle gain make sure to adjust how early/late in a pass the recording runs. This can be found under Recording Options and is set by elevation angle on each side (useful if you’re blocked on one side - you can ignore it). Set a starting angle (bottom box) and a max elevation above which you want a recording to happen at all (top box). | + | |
- | + | ||
- | ==== NOAA-APT ==== | + | |
- | + | ||
- | **Enhancements** - NOAA-APT is a bit crap in this department, particular in how it handles the false colouring of images. See what you think - this is going to be a personal choice. If you find a good position for the sliders then well done! | + | |
- | + | ||
- | **Map overlays** - this actually works well (and the adjustable-per-second correction can be very useful vs the fiddly WxtoImg “drag map overlay” option or messing about with timestamps). You will have to make completely transparent the lines you don't want to see, however, as you can't toggle things on and off. | + | |
- | + | ||
- | ==== SatDump ==== | + | |
- | + | ||
- | If you don’t need map overlays for your LRPT captures then SatDump is a great solution that does everything you need and chucks out good images of a few different types. It’s certainly easier than setting up SDR# and multiple plugins and decoders and also opens up the world to further decoding of other satellites in other bands. | + | |
- | + | ||
- | Do make sure you select the right sample rate (bandwidth selected in SDR application) and type when loading in your baseband. The box expects bits per second, rather than kilobits per second. | + | |
- | + | ||
- | ==== LRPT Decoder ==== | + | |
- | + | ||
- | Symbol .S/.soft files have to have a specific filename or they won’t show up in the file open box, even if the extension matches. The format is that put out by the SDR# demodulator plug-in. If you want to load in a renamed file or a file from something else like SatDump you’ll need to type the first few characters and you’ll be able to click on the one you want. Annoying. That’s ham radio software, though! | + | |
- | + | ||
- | Additionally, | + | |
- | + | ||
- | ==== MeteorGIS ==== | + | |
- | + | ||
- | Honestly, don’t worry if you can’t figure this out. The software is absolutely horrible and very much part of the “someone made it work for them and then stopped caring” school of software development. As you’ll see from the pages online it has a specific list of requirements for things like folder and file names and the command line is unforgiving if you’re doing post-pass decoding. If you’re set on projections/ | + | |
- | + | ||
- | (Put some useful commands here) | + | |
---- | ---- | ||
- | ====== General tips/data for APT and LRPT decoding ====== | + | ===== Contents |
- | <WRAP left round info 25%> | + | |
- | ===== Frequency list ===== | + | * [[vhfwxsatellitetips-hw|Hardware overview]] - including SDRs/ |
- | * **NOAA-15:** 137.6200 | + | * [[vhfsatellite-sw|Software overview + tips]] - some of the software used to do this work is awful - here's some useful tips for various |
- | * **NOAA-18:** 137.9125 | + | * [[vhfsatellite-general|General tips/ |
- | * **NOAA-19:** 137.1000 | + | |
- | * **Meteor M-N2:** 137.1000 | + | |
- | </ | + | |
- | + | ||
- | Obviously for those of you wanting | + | |
- | + | ||
- | **APT:** FM, 34 kHz signal, set filter bandwidth to around 35-40 kHz. If you’re correcting | + | |
- | + | ||
- | **LRPT:** FM, 120 kHz signal, set filter bandwidth to around 130-140 kHz. Doppler correction isn’t strictly needed as the demodulator tools can pick out the data and lock onto it just fine. An SNR of around 10 dB will decode fine, but you may even get some data coming through around 5-10 if you're lucky. Just don't expect | + | |
- | + | ||
- | For LRPT work remember that it’s the raw I/Q baseband recording that you want if you aren't decoding live, not an audio recording. For APT you want the audio recording. | + | |
- | + | ||
- | + | ||
- | <WRAP center round important 60%> | + | |
- | If you’re switching between receiving the two types of signal don’t forget to check your Doppler/ | + | |
- | </ | + | |
- | + | ||
- | If you can avoid DC spikes by using offset tuning or a filter function it can help, particularly with LRPT. If it’s baked into your recording | + | |
- | + | ||
- | You'll need more gain for LRPT signals because of the similar power but lower bandwidth (power density). This can induce intermod/ | + | |
- | + | ||
- | ===== Audio Samples ===== | + | |
- | + | ||
- | Here's a couple of audio samples | + | |
- | + | ||
- | <WRAP left round info 40%> | + | |
- | ==== APT Sample ==== | + | |
- | 11,025 kHz mono WAV file, (size here) | + | |
- | | + | |
- | </ | + | |
- | + | ||
- | <WRAP right round info 40%> | + | |
- | ==== LRPT Sample ==== | + | |
- | 250 kHz wide baseband I/Q WAV file, (size here) | + | |
- | (link here) | + | |
- | </ | + | |
---- | ---- | ||
- | ====== OARC reception gallery ====== | + | ===== Community Links/ |
- | + | ||
- | If you're adding entries please add the start time of the pass, or for composites feel free to specify a time range. | + | |
- | + | ||
- | ===== APT Captures ===== | + | |
- | ^ Capture | + | There’s lots of places where you can find some more information on reception, software, antennas, and all other relevant topics: |
- | ^ [[https:// | + | |
- | ^ [[https:// | + | |
- | ^ [[https:// | + | |
- | ^ [[https:// | + | |
- | ===== LRPT Captures ===== | + | **Reddit:** https:// |
- | To follow. | + | **LibreSpace: |
- | ^ Capture | + | **Twitter: |
- | ^ [[x|{{x}}]] | + |
vhfwxsatellitetips.txt · Last modified: 2022/05/08 01:39 by mm3iig