[RTTY] TinyFSK modem for 45 and 75 baud

[Ed Muns]

Nothing ... IF your computer has real, i.e., with good UARTs, hardware
serial ports., or you use a USB-Serial converter such as the Edgeport units
with real UART components.  However, many people use standard consumer-grade
USB-Serial converters without true UARTs and they therefore require the
EXTFSK optional module for MMTTY to provide correct Serial timing.  Turns
out that MMTTY's EXTFSK's "correct Serial timing" is not so correct.  Thus,
a solution like Andy's is warranted to obtain perfect RTTY timing via USB.

The Edgeport converters are commercial products retailing for over $300, but
I've bought lots of them for $30 or less (4-port) and $60 or less (8-port)
on eBay.  Just two different approaches to obtain proper Serial timing.

Ed W0YK

Andy K0SM/2 wrote:
> >For those of you looking for a relatively simple and 
> inexpensive method of doing 45 and 75 baud RTTY using logical 
> keying ("FSK") you can have a look at a TX-only modem that I 
> built that will accomplish this.

Bill W6WRT wrote:
> 
> REPLY:
> 
> What does this do that MMTTY and a pair of one-transistor 
> drivers for FSK and PTT does not do?