Add Navtex decoder

[rst5nn]

As this great rig is able to work on MF, I think this could be interesting to add support of Navtex weather information.

[hitam4450]

That sounds great and makes that little thing even more useful...

[rst5nn]

Looks like the audio output is not wired to the CPU.
That is any audio sampling and processing is not possible =(

[dustinsterk]

This guys firmware supports a "decoder" function with a simple hardware mod: http://www.hjberndt.de/dvb/pocketSI4735DualCoreDecoder.html

[EmEiBee]

It doesn't just look that way, it's true ;)
This point has been discussed here many times in various contexts.
You could use an IO pin on an A/D, but for one thing, it conflicts with other things, like Wi-Fi, and for another, the ESP isn't really designed to process audio signals via an internal A/D.

[DE8MSH]

hjberndt used a single wire to sound (speaker) to es32. i did the mod and it works for rtty. a navtex or sitor b decoder would be great then! turkish naval stations sending sitor b news via hf.