direwolf

On this topic, has anyone here used direwolf (https://github.com/wb2osz/direwolf) to communicate between two computers without radios?

Wheel successfully reinvented :) Nothing stopping you setting up a whole AX.25 network between multiple machines using Dire Wolf [1] and the built-in AX.25 [2] (a derivation of X.25) support still in the Linux kernel. You get a proper network interface that shows up alongside eth0. Nice short instructions at [3]. Just don't hook it up to radios unless you're appropriately licensed. Speakers and mics only. [1] https://github.com/wb2osz/direwolf [2] https://en.wikipedia.org/wiki/AX.25 [3] https://g7vrd.co.uk/ax25-direwolf-linux

If you can get your hands on a new-old-stock MX614 IC, it's semi-simple to play with in hardware. There are many software-based packages as well if you're more inclined to enjoy that style. mx614 circuit - https://www.cmlmicro.com/wp-content/uploads/2017/06/FAQs-MX6... attiny style - https://sites.google.com/site/wayneholder/attiny-4-5-9-10-as... direwolf softmodem - https://github.com/wb2osz/direwolf

LWN usually has great content but they've missed out on so much free ham software in this article that I use regularly. My main HF rig is an older Yaesu FT-950. I tapped the IF and brought it out of the chassis where it is plugged into a cheap RTLSDR. I then access that RTLSDR (with free drivers) with GQRX (free software for visualizing anything compatible with SoapySDR or GNU radio), and the result is that I get a panadapter that is arguably better than what's available on $2000 radios. Short video here: https://photos.app.goo.gl/uP9zMMbiiiSmHYvM8 As for VHF/UHF stuff, I would be hopeless if it wasn't for GPredict on my laptop making it simple to track LEO satellites. https://github.com/csete/gpredict Short video here: https://photos.app.goo.gl/eg87BWpt2XnJdGFp7 I also run an APRS igate, which is powered by direwolf: https://sielicki.git

I remember the hate that closed-source Winmodem got back in the 90s but software-defined modems can be far superior to hardware. Case in point: direwolf. I think it decodes APRS better than any hardware solution. https://github.com/wb2osz/direwolf

The FCC license registration [0] contains some interesting information. - Experimental radio service call sign WM9XPA - Using an Icom IC-821C Transceiver [1], a twenty-something year old VHF/UHF ham radio...wow for a $7M project couldn't they have spent more on a radio? Well, maybe not, I'll get to that in a minute. - Ground station is in the middle of nowhere? I think something with the Lat-Lon might be off if they mention West Lafayette, IN as the city (Purdue is located here). - The satellite's datalink is FSK on 437.025 MHz, designation 15K0F1D, which is a standard 15kHz wide FM modulated FSK signal. The signal's parameters are not known from the registration but I googled some more and found their FAQ which links to their protocol description [2]. In a nutshell it's run-of-the-mill AX.25 at 9600baud using a simple encoding for variou

Ham radio. 300 baud packet over HF (thousands of miles) is still a thing, as are newer data modes such as PSK31 and the JT family. I'm actively working on 1200 baud projects over VHF FM now. Back in the day BBS was very much in. These days the same tech is more often used for telemetry, tracking etc (APRS). Now you can do it all in software, ref https://github.com/wb2osz/direwolf and friends.

I've been working on open-source balloon control software [1] for my own balloon project that I've been building on/off for about six years. I am hoping to use a software modem to bridge between the RF and my AX.25 packet reader/writer [2] because I wanted to save weight. Payload weight is the name of the game in the balloon hobby--the lighter your payload, the less you have to inflate your balloon and the higher it will fly before it bursts. Even an ounce matters and the competitive altitude record balloons are invariably tiny, single-board, all-in-one payloads that are built around a single low-power microcontroller. There are a couple of good open source options for software-based AFSK APRS modem/TNCs: Dire Wolf: https://github.com/wb2osz/direwolf minimodem: https://github.com/kamalmostafa/minimodem You'll still need a USB sound ca