How To Decode L band Satellite ACARS and CPDLC messages with JAERO and your SDR 

Great tip Evan, thanks for sharing!

hi i ggoled and found the link to skytalec software but it seems its not available anymore ,do you hapen have a link you can send ? please

Thanks for the positive feedback!

Thanks Alain 🙂

Fantastic! It certainly feels exciting when you can start pulling down all these messages from the satellites. Loads of fun. I'm hoping I'll have another L band video this Summer which will show you how to do even more! Thanks for the donation. Much appreciated.

Glad the video was useful!

Good luck!

Yes, thanks...I will need all the luck I can get!

You're welcome Leo. I'm pleased to hear the video was helpful. Thanks for letting me know!

Glad to hear you're enjoying it!

You're welcome!

Not quite. ACARS works on VHF. CPDLC messages are via satellite in the 1500 MHz range. 1090 MHz is for ADSB.

No, the L band signals are fairly weak, so the gain needs to be kept at maximum. I just adjusted the Range & Contrast sliders in SDR#.

Nice catch with AF1 Tim. That's fantastic! I've picked up several SAM flights in the past. Yes, have definitely noticed plenty of USAF activity on the 600bps transponders. Hadn't picked up on the geographic ones before though. That's interesting to know. I noticed several South American aircraft on the 600 channels, however I mostly monitor the 10500. A future project will be to ingest all transponders at once and set up a filtering system for certain messages. That's a longer term project though! Thanks for your support of the channel.

Hi, can you tell us, how do we know, if it's 600, 10,500 12500 bps, if the decoder (J.) doesn't recognize it automatically? Thnx 👍

You can tell by the bandwidth. The 600bps channels are about 6 kHz wide, the 10500 baud channels approx 11 kHz wide.

Ha ha, glad to hear you've now been successfully decoding Wayne. I'm sure there are many who didn't turn up the gain, myself included! There is a lot of traffic to see, so enjoy!

G'day Rob@@FrugalRadio so yesterday was just a trial before doing a full install. Next I want to experiment with a dish to try & increase the gain. I just want everything @ 100% @ ground level before I permanently mount at height.

Are you getting a good decode on the 10500 transponders? That's where most of the activity seems to be, at least on the other 3 Inmarsat birds. I've never been far enough East to pick up 143! What kind of SNR are you getting? When I get round to permanent mounting at the new place, I want to run simultaneous decodes on multiple transponders. It has worked in my experiments, but trying to keep up with all the data is almost impossible. So I'm going to experiment with text-based filtering and categorizing. I installed one of the software pieces that will do the work last night!

G'day again Rob @@FrugalRadio so this weekend just gone was my 1st foot steps into Inmarsat just using my work laptop I left it running for 12 hours until 6am this morning on a 1200BPS transponder and woke up this morning to some really interesting data but until I get "An Inmarsat Antenna" permanently mounted and installed I won't know if I can get any of the 10500 transponders or not. I'm really keen to expand my knowledge, use and decoding of Inmarsat data including looking at how the "Control" channels work I wish there was software like there is for trunking where you could just monitor the Inmarsat control transponder and when it spits out a goto frequency for a voice call the software just takes you there. I'd be really keen to know who you go with your project please keep me in the loop. Based on one of your videos I have just recently purchase a heap of Nooelec gear so as time allows with family & work I plan on putting some of it to good use. Also really pived that the database is no longer available & from the research that I've done no one seems to be able to find the code to rebuild a new one which leaves me with the question why is it no longer available it really takes away from the main software That being Jaero. You mentioned that you had a database....... I've tagged your RU-vid channel you in several posts that I answered on several groups that I belong to some of which you are also a member of where people are looking for help understanding Inmarsat. The problem with this hobby is that there is so much abandoned-ware. I'm also cautioning people about just what they post up in the fear that Inmarsat will just go "Right we are encrypting the whole thing " and we will lose everything. Stay in touch. Rgs Wayne

It turns out there is a 'hidden' version of Jaero which includes an updated database (from March this year). However the database is now in basestation SQL format. This means that users can update it. I haven't tried this with the 'hidden' version yet. I say hidden, but it is actually a public Alpha or beta version available on the GitHub page. It's just tucked away and hard to find!

It is receivable, yes. However a large, C-band satellite dish is required. See thebaldgeek.github.io/C-Band.html

Thanks!

Hi. Yes, bias t provides power to the LNA inside the patch antenna. This is required to produce a high enough signal to noise ratio to enable decoding. Make sure bias t is switched on when using this patch antenna.

@@FrugalRadio thanks for your quick reply ,do you have a video on how to do this ?

It would depend on the SDR you are using. If it's an RTL-SDR v3, instructions are at www.rtl-sdr.com/rtl-sdr-blog-v-3-dongles-user-guide/ under Feature 2. NooElec SDRs do not have a switchable bias tee. You either buy the one with permanent bias tee (SMArtee), or the one without (SMArt). Please refer to the user guide for your particular SDR.

@@FrugalRadio ok thankyou very much

Good idea!

@@FrugalRadio Making one, snagged some PCB boards from eBay ... looks like a fun project.

Excellent. If you have a 3d printer, you can also create a small helix antenna for L band. They provide excellent reception from what I hear. Try looking up homebrew L band antennas for several designs 🙂

@@FrugalRadio I've ordered some copper PCB for a homebrew plate antenna. Will check out the helix. 3D printer might be a fun addition, not got into that yet.

Ah yes, building your own plate, nice. Let us know your results when you get it all assembled and tested!

Glad you enjoyed it!

Hello and thanks for your support on the channel. I haven't done a great deal with satellite decoding - at least when it comes to weather satellites. I would recommend checking out some of the articles on the RTL-SDR blog. Lots about satellite decoding there.

@@FrugalRadio thank you for the suggestion! much appreciated. look forward to more videos!

Yes, there are a couple of GOES weather satellites that download in the L band. To receive them, you generally require a dish. I hope to demonstrate a set up in the future!

@@FrugalRadio will be more than a happy to see a tutorial about this in the future.

Good to know it will be interesting to some viewers. Appreciate you letting me know.

Great video. Can you tell me for central Oregon which satellites I could hear from here. I read where some satellites are not going to be used as they have reached EOL. So what is the deal going forward for my area? It appears there aren't many places to get this antenna. All the best, George

98W would be your main sat. Loads of activity on them - so much it's hard to keep up!

Yes, aviation voice comms are also carried on the satellites.

@@FrugalRadio Thank you very much for getting back to me much very appreciated hope you are doing well and looking forward to more of your videos kind regards Peter

Links to the software are in the lower part of the description.

All the download links are above in the description ( github.com/jontio/JAERO/releases )

@@42markk42 thanks for the help, I think I was looking at the guys old website which wasn’t very helpful

For voice, you leave the virtual cable selected. JAERO will demodulate the digital ambe audio and automatically route it to your speakers 😃

@@FrugalRadio Thank you. I got it working. I had my laptop speakers disabled so I wasn’t hearing anything.

Excellent. Glad you're able to monitor the voice transmissions now!

Yes, I could get Alphasat and 54W when I lived in Ireland. Good luck!

A patch antenna like this is very directional, so you would definitely need to point it carefully towards to Southern part of the sky until you see the signals. Then adjust for peak reception.

I believe it is AMBE

THere's more to it than Frugal Radio is letting on. YOu have to compile, or use a release that already has the .dll for the AMBE release (I"ve been told the latest one has it tho there is NO MENTION OF IT in the releast notes. Compiling it is a NIGHTMARE.

The higher bandwidth signals are more difficult to receive as they are weaker. The 600bps ones are the strongest. The 8400bps are the most difficult to pull in, as the power reduces when a transmission begins. For 10500, make sure your SDR bandwidth is correct (should be around 11-12 KHz - the whole signal should fit within the bandwidth window). You might also want to keep a close eye on the signal to noise ratio (SNR), and JAERO Eb value. Move your antenna to get these as high as possible. The stronger the signal, the higher chance of decode. Also check your volume output level on your SDR software. If the volumes light is green in JAERO It's fine, but if it is a different colour, you'll need to adjust.

@@FrugalRadio thank you very much I’ll keep trying

@@FrugalRadioHi is it possible i could email you regards Peter

Hi Peter. The satellite moves in the sky a little, so it is normal for signal strength to go up and down a bit. The frequency should be stable though, but on USB mode it will be a few kHz different from what is published. As long as the drift is not coming from your SDR itself. Do you notice the frequency changing each day on VHF & UHF signals?

@@FrugalRadio hello, thanks for answer. The vhf & uhf signals on the sdr are stable , so it can be that i not adjust the antenna good. Last question for adjusting which satellie nust i have in the West (i live in The Netherlands and have good view from South- West to West)or must i adjust between these that is not clear to me. Good channel you have and thanks for the good videos. Greetings Peter

Hello again Peter. Yes, good decoding relies on a clear path to the satellite. Trees and buildings create problems for the satellite signal. From NL you could expect to receive a signal from 54W, and 25E. If your view is clearer to the West, I would try the 54W satellite first. There are some apps, such as Dishpointer, which can help you find the location of the satellite from your position. It might be worth trying one of those as you get started. Best wishes!

Hi Wayne. Have fun getting the patches running. There really is a ton of data coming from the 10500 bps transponders, at least on the sats I've seen. With your prior satellite experience I'm sure you'll be decoding in no time! As for C band, if I ever get a dish, then yes, I'll do a video. I see old 2-3m prime focus dishes all the time in people's yards when out walking. However I'm moving back to my own property next month which is much smaller, and the south facing yard is surrounded by trees. Also, the wife hated my old 1.2m Ku band dish when I lived in the UK. Not sure how she'd feel about seeing a mammoth contraption like a C band dish in the garden!!!

Thanks Rob@@FrugalRadio fortunately for business unfortunately for my play time we are in the middle of an exteremly busy time so sadly it will be July some time or maybe later before the L-Band sees the light of day. Just for your & other subscribers information after wasting 2 x solid days & dozens of support emails back & forth in direct relation to the RTL-SDR & the SDR PLAY infrastructure it has finally being acknowledged by SDRplay that the Microsoft Surface Pro X will not work with either SDR because of the proprietary ARM chip. Take care Regards Wayne.

Hmm, sorry to hear about the problem with the Surface X. That's a bummer. Could have made a nice little portable platform for SDR.

Yes, that is a common error. It usually appears when first decoding a signal. As long as that message stops after a few seconds and you have the green lights, all will be well. If the message continues to appear after a few seconds, try adjusting your audio or SDR receiver settings.

@@FrugalRadio you are awesome.i greatly appreciate the reply.it does seem to have the error message come up every so often but is not constant.i see also at the end of the video you are able to hear audio. i did a seaarch in you current videos on how to set it up but did not see anything that shows how to set it up.i could have passed it and not understood what the video is about but am watching them one by one to find it if available.i did copy the settings as shown in the video here but did not hear anything.i know im missing something but not sure what.is there a video or even a website for setting it up properly that you know of..thank you again.i really appreciate the help and see why people are into radios as im a 3rd generation "enthusiast"

No worries. The audio is a little more difficult to set up. You tell JAERO to decode at 8400bps, and set your bandwidth accordingly. As long as you have the correct libraries installed (I don't remember what they're called), it will produce audio. I haven't made a video specifically about it. One thing to note is that the 8400 channels come and go. They also dynamically reduce power after an audio connection has been initiated. So you may hear part of a call, then see the signal lower and possibly drop completely. Have fun experimenting!

I would check the following : Is JAERO receiving the audio? Is your bandwidth in SDR# set correctly? Can you see the signal hump in JAERO? Sometimes it helps to left-click in the centre of it. Is the appropriate speed for the transponder selected in JAERO?

JAERO does not appear to be receiving the audio. There is no activity in the constellation box or the spectrum. I am using the VB Audio.Virtual.Audio.Cable x64

If JAERO isn't getting audio, check that the correct soundcard is selected in the JAERO settings. Then check the volume slider in SDR#. If JAERO is receiving audio, you will see a green light at the bottom beside Volume. If the light isn't green, the volume is probably too low in SDR#. If it goes red, the volume is too high. See if changing that gets you any signal.

receiving data on a laptop. still can't it to work on desktop but will keep trying. thanks

If you've got it running on one machine, but not the other, that seems odd. From there I might try reinstalling the virtual cable, and ensuring no other device software is producing sounds on the VB cable channel. Hopefully you'll get it figured!

Jonti, author of JAERO has provided instructions at github.com/jontio/libaeroambe/wiki/Building_64-bit_binaries_for_Windows

@@FrugalRadio looks like a job for computer superman as I am limited skills

Yes, it isn't for the faint of heart. A few years ago I'm sure I found a codec online that just worked, because I don't recall going through the process of building it like that. I've had a look around, but haven't been able to find it again.

Look in the comments below this article: www.rtl-sdr.com/aero-c-channel-voice-audio-now-decodable-with-jaero/ . User Kotelnikov007 has made a useful download available on MEGA. The link is in the comment.

@Ajen66, thanks for posting this. I knew there was a file out there somewhere, but didn't know where!

For Windows I only ever downloaded the pre compiled binaries... Try the windows asset at github.com/jontio/JAERO/releases

@@FrugalRadio so would this be ready to run and has all of the dependencies. And is there a precompiled of the needed voice library?

I believe it is all included. Click the little triangle next to the Assets heading, download the windows one, unpack it in your drive and see how it goes!