mt63_wasm
This is very much a work in progress; the idea is to compile a mt63 library to wasm using emscripten to allow encoding MT63 messages and "sending" them from an HTML5 audio web application; this could be used to reliably transmit data from a smartphone app across Amateur Radio FM signals on VHF/UHF.
Preparing to build
Currently we have it set up to build on linux or macOS.
First you need to have cmake installed. Next, check to see what versions :
cd emsdk_portable
./emsdk install sdk-1.38.4-64bit
Note that you might need to do emsdk list and install a different version as it won't let you install older versions by default.
Building
Once that's done, building is a simple two-step process:
./prepemscripten.sh
cmake --build build/
You should now have a build/ directory. Copy index.html into the build/ directory and run some sort of static web server there. I use node-static: npm install -g node-static. If you have node-static installed you can start a server like so:
cd build/
static .
Open http://localhost:8080 in your browser, open a console, and run sendMessage("This is a test message"); You should hear the mt63 come through.
Status
Currently sound is being generated and can be de-encoded in FLDIGI! For mobile browsers that cannot play at a sample rate of 8000 Hz we've played a 3 to 1 trick telling AudioContext that the buffer is at 24KHz but to play it back at 1/3 speed.
Shameless plugs
This project relies heavily on the fldigi MT63 code and was put together by Richard Bateman, founder of HamStudy.org. To support our efforts, check out https://signalstuff.com/antennas (our main source of funding) and https://hamstudy.org/appstore for well engineered study apps for only $3.99.
License
mt63-wasm is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
mt63-wasm is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this project. If not, see http://www.gnu.org/licenses/.