carl9170fw VS mlat-server

The carl firmware at https://github.com/chunkeey/carl9170fw should put that argument to rest. That is Wifi firmware source code for the Wifi I currently use.

Easily changed likely means there's a physical knob somewhere that you could accidentially poke as a layperson.

Not that you get a three year CS education, figure out how your distribution packages dependencies, install the correct embedded toolchain (good luck), find out exactly which chip is in your device, fetch the proper firmware source code in the right version, build the thing, figure out how to flash the result onto the chip / read the Linux kernel sources to figure out the filename inside /lib/firmware. That's not easy.

Even if this entire process was packaged (it is--see <https://packages.debian.org/sid/firmware-linux-free>), it probably still doesn't count (or at least shouldn't count) as "easily" changed.

There are some cards with open source firmware, you might be able to modify it to do something like that.

https://github.com/chunkeey/carl9170fw/

I would suggest not starting in the 2.4GHz band, the protocols used there (wifi, bluetooth) are very complicated to understand. Get a rtl-sdr and start with something simpler: FM broadcast (my blogpost: https://www.abclinuxu.cz/blog/jenda/2019/11/gnu-radio-first-..., there is even an example capture you can download and replay, so you can start even without the physical radio), police radio (both analog and digital), radiosondes, weather satellites, ISM stuff - temperature sensors, garage and car remote controls, airplane multilateration (https://github.com/mutability/mlat-server)… You can do lot of stuff even with the $10 rtl-sdr, for example I have used it for multilaterating TV and radio transmitters (thesis: https://jenda.hrach.eu/dipl.pdf, unfortunately "layman's explanation" is available only as a lecture in Czech). I know people are even building radioastronomy stuff and passive radars (https://www.rtl-sdr.com/passive-radar-dual-coherent-channel-...) with rtl-sdr.

Once you have basic understanding of the topic, you can get better hardware: AirSpy (the same features as rtl-sdr, but MUCH better signal-to-noise ratio and bandwidth) or bladeRF (costly, but probably the best radio you can get now). For example I'm now building a weather radar based on bladeRF. The bladeRF has a FPGA with open-source HDL, so you can mess even with absolutely lowlevel and bleeding edge stuff.

Going back to your original question:

Most cards load firmware from a file when they are initializing (check "dmesg|grep firmware", on my machine, for example, it says it has loaded /lib/firmware/rtl_nic/rtl8153b-2.fw), you are free to modify it. However, all (or maybe almost all) wifi cards have the format of the blob completely undocumented so it would be very hard to make a modification that would allow you to transmit/receive arbitrary signals. Something similar has been achieved with GSM phones (see OsmocomBB), but it requires very complicated reverse-engineering.

Recently, there was a wifi stack released for a SDR, so the other way around: https://www.nuand.com/bladeRF-wiphy/.

I got the code from https://github.com/mutability/mlat-server does anyone know how to get it up and running any assistance would be much appreciated and extremely helpful :)