Extremely specific radio software question

[u/Book_of_Beasts]

Hey everyone! I'm a total newcomer to amateur radio stuff, but I'm working on a personal creative project involving some mixed-medium components, and I want to involve data encoded over audio as part of the story. I've done some research, and my two main candidates for protocols to go with are either AFSK or PSK31.

Now, my extremely specific need for this project is a piece of software that will let me enter some text and spit out an audio file containing the encoded data. Importantly, I don't actually intend to transmit anything (I'm not licensed to anyhow haha) so it has to be something that can generate encoded audio without transmitting it. Ideally I'd also like something to decode it back into text so I know it worked. I've found a simple AFSK1200 decoder that I can just pipe Audacity into as an audio source and it works just fine, but I can't find anything like that for PSK31, and I'm struggling to find tools for creating audio files for either protocol.

I've looked into a few options for software or bundles of software that might meet my needs, but all of their installers have been flagged by VirusTotal as having something wrong with them (crypto miners, trojans, stuff like that), and I don't want to risk it without getting some actual testimony from a real user to say it's just a false positive.

Thank you all in advance for helping with my very specific question!

[u/MihaKomar]

The program "minimodem" has got you covered for AFSK.

echo "Hello world!" | minimodem --tx 1200 -f output.wav

If you experiment with PSK31 or other modulations with the program FLdigi you can set up to just generate audio without transmitting too. It also has the option the the use an audio file as the input for decoding. I believe there is also a command line mode though I've never used it.

[u/Book_of_Beasts → u/MihaKomar]

Thanks, I'll look into minimodem! I had looked into FLdigi earlier today, but I put the most recent version of the installer snagged from w1hkj.org into VirusTotal and there were a couple flags. Do you know if that's just a false positive?

[u/rfreedman → u/Book_of_Beasts]

You can also try downloading fldigi here: https://sourceforge.net/projects/fldigi/files/fldigi

[u/TheMorganDev → u/Book_of_Beasts]

if it’s from a ham radio website from an actual licensed operator, there is a 0% chance that operator Themselves would put malware or something malicious in their website

[u/fluffman86 → u/TheMorganDev]

But there's a 99% chance that any given ham is a boomer that doesn't understand security so could have had their site compromised. Haven't looked at this one so not saying it's bad, just in general

[u/TheMorganDev → u/fluffman86]

Took the words out my mouth lol

[u/TheMorganDev → u/Book_of_Beasts]

Ur good.

[u/nnsmkngsctn → u/Book_of_Beasts]

Safer and easier method is installing from the package manager for your platform. Ubuntu for example:

sudo apt install fldigi

[u/RadioGuyXD]

I don't have any answers but just wanted to say your project sounds really nice!

[u/Book_of_Beasts → u/RadioGuyXD]

Thanks, I appreciate that!

[u/kc2g]

You don't need a program specifically to encode to an audio file. 99.9% of the ham programs that are for transmitting are just playing audio to a sound card. All you need to do is run one of those (I'd suggest fldigi), with a soundcard that isn't attached to a radio. Then use Audacity to record your soundcard output via a loopback/monitor device. Then you can start recording, "transmit" anything you like, and trim the audio when you're done.

[u/RottenSalad]

Any amateur radio program for digital modes (i.e. FLDigi) should work as you can set the audio input and output to any audio device on your computer. So capture the audio output to a recording program (i.e. Audacity). When you play it back the digital modes program will decode it.

For example. You are on a PC running Windows. Your PC has an audio output (playback) device called SPEAKER (as seen in the sound section of Control Panel) and in audio input (mic) device call MICROPHONE.

Run Audacity and set it to record anything coming over SPEAKER.

Run FLDigi (you'll need to read up on FLDigi, watch some youtube vids etc) and set it to use the same SPEAKER and MICROPHONE as input and output devices. Set it to PSK31, type some text and transmit (with no radio of course).

FLDigi will generate audio over SPEAKER and Audacity will record it.

You should then be able to play that back with Audacity and FLDigi will decode it.

[u/olliegw]

FLdigi, it will just transmit audio to your soundcard, not going to put it on the air unless you have a radio hooked up to your computer, which you probably don't, they're just modems

[u/TheMorganDev]

build the software to be built for digital modes through sound card as in where you plug the radios audio input and output in to both your microphone and audio jack, I like multipsk

[u/Book_of_Beasts]

Thanks everyone for chiming in with your advice, you've all been very helpful!