[GreenKeys] MMTY

[John Gibbs]

There is a way to use MMTTY as a baudot modem.  It would seem only a  
level converter transistor would be needed to extract the RS-232 data 
available on the com port to drive a HV loop keyer transistor.  It works 
here using another baudot terminal, don't have a iron machine  to try it on.

I have used MMTTY for years and compaired it to other software programs 
and hardware modems using the same radio rtty signals and it always did 
the best copy.

Here is a copy of the help file in MMtty that refers to the modem setup.

73 John / VE7BDQ

/Use MMTTY as a Modem
Hardware Setup
  - Two Computers
  - One Computer
  - Null Modem

Software Set-up  

-----------------------------------------------------------------------------
MMTTY can function as if it were a terminal node controller, or modem.
This mode was useful when there were other programs that could do logging
or contesting, but required a modem to operate RTTY. This feature has
remained in MMTTY.

Some contest and logging programs make provision to use MMTTY in the same
computer as the contest or logging program, and no longer require 
work-around.
Others use this technique.
 

Hardware Set-Up

 
You can use MMTTY as a modem by using two computers,
or one computer with two serial ports that can operate at the same time.
 
Two Computers
 
One computer runs the contest program that expects a modem to be
connected to a serial (COM) port. A second computer runs MMTTY,
and specifies a COM port as MMTTY's output of decoded data.
Connect the COM ports of the two computers with a null modem (crossed 
wires).
 
One Computer
 
The same computer runs both the contest program and MMTTY.
In the contest program, specify a serial (COM) port as the place where
a modem is attached. In MMTTY, specify a different serial (COM) port as
the output of MMTTY. Connect these two ports on the same computer with
a null modem.
 
Null Modem
 
A null modem is a pair of wires crossed so that the output of each
computer is connected to the input of the other. For a DB-25 (25-pin)
or DB-9 (9-pin) COM port connector, pins 2 and 3 are crossed.
Pin 2 on the first end of the cable is connected to pin 3 on
the second end of the cable, and pin 3 on the first end is
connected to pin 2 on the second end. This setup is not the
"official" way to make a null modem. A real null modem cable
has other connections as well, but for MMTTY, these are the only
connections you need. You can purchase a standard null modem cable
at Radio Shack.
 

Software Set-Up
 
Set-up MMTTY as a modem using the computer on which it is running.
 
Click Option | Setup TNC emulation, and view the following display.
 
 
The port definitions are straightforward. Both computers must use the
same settings for baud, data length, flow control, stop bits, and parity.
Port numbers can be different, as long as the correct ports are connected
with the null modem. You can make MMTTY emulate an MFJ TNC 241, a KAM, or
a Baudot TU.
 
To see MMTTY's output on the computer that is running MMTTY, you may have
to play with the echo selection.
 
Decoded characters should appear in your contest program once MMTTY is 
running.
 
MMTTY can control a transceiver using software control, key PTT via a port,
or operate FSK. Even though you control the MMTTY modem computer from 
another
computer as if it were a KAM, the modem computer can do most of the
 things that MMTTY can do.
  /