[RTTY] USB serial port adapters

[Lee]

Now for my next question: why is FSK RTTY difficult when using USB 
serial port adapters? One article I read was saying that 45 baud rtty is 
too slow for the adapter while another said that they don't handle 5 bit 
characters. From my research POSIX allows you to specify 5 bit 
characters.   Anyway, I'm writing a C program under Linux and I have 
successfully got an adapter with a PL2303 chip to send FSK RTTY at 45 
baud. I had to write code for a custom bit rate since 45 baud isn't a 
standard rate. Anyway, my project is still WIP, though. I've noticed 
that there's EXTFSK for MMTTY and I've tried it - works for me - but I 
want a program that runs on Linux. If the developers of FLDIGI ever 
decide to incorporate FSK into their code or if another developer puts 
out a native Linux FSK RTTY program, I'll drop my project. I don't want 
to build an adapter to convert audio tones (AFSK) to FSK (pseudo-FSK). 
Hopefully nobody thinks I'm being critical of any developers - I just 
want to know what's going on and why.

N0SQ