75 Baud RTTY Setup

Running 75 Baud RTTY with WriteLog

Most Amateur HF RTTY is run at a rate of 45 baud (also known as 60 WPM). Baudot (RTTY) rates supported by WriteLog are 45, 50, 57 and 75 baud. Most RTTY contests are run at 45 baud. However, the BARTG Sprint 75, which occurs twice a year in April and September, specifies 75 baud RTTY only (also referred to as 100 WPM).

If you plan on participating in the BARTG Sprint 75, open WriteLog as you normally would and opt to Start a new log. Select BARTG Sprint as the module.  The rules for BARTG Sprint and BARTG Sprint 75 are the same.  The only difference is 75 baud RTTY is used for the BARTG Sprint 75.

When using a sound card modem such as 2Tone, MMTTY or WinRTTY, there are some considerations that need to be made. For one, a USB-to-serial adapter is not likely to be capable of generated 5-bit Baudot (RTTY) at a baud rate of 75 baud when transmitting FSK EXCEPT with perhaps some Edgeport models OR when using MMTTY’s EXTFSK64. 75 baud RTTY can be achieved using EXTFSK64 as long as your computer’s processor (CPU) will handle the load. Be sure to read additional information on EXTFSK64 here. (Note: There are no limitations to running 75 baud AFSK with WriteLog.) Normally when using a USB-to-serial adapter for FSK, you are forced to use either Software Generated FSK or MMTTY EXTFSK which are limited to 45 baud. This is shown when you activate Software generated FSK from the Port menu in Rttyrite.


For FSK users that do not rely on Software generated FSK or MMTTY EXTFSK, baud rates other than 45 baud can be achieved. If you use a microHAM interface, detailed instructions on setting up your device with WriteLog can be found on the support page on the microHAM USA website at http://microham-usa.com/store/cmspage.php?page_id=11. If you use a legacy COM port (one built into the motherboard of a computer, or installed in a PCI or PCI-X slot of a desktop PC, or a PCMCIA serial card in a laptop computer) for generating FSK with a sound card modem such as 2Tone, MMTTY or WinRTTY, the information below will show how to set up for 75 baud RTTY.

2Tone 75 baud FSK Setup
MMTTY 75 baud FSK Setup
WinRTTY 75 baud Setup

2Tone 75 baud Setup

With 2Tone running in Rttyrite, open 2Tone Settings and select 75 Baud then click OK.


If you are running AFSK, there is nothing else that needs to be set. If you are running FSK, go to the Rttyrite Mode menu and select 75 baud (100 WPM) Baudot. You are now set for 75 baud RTTY both transmit and receive. (Note: You must use Hardware Generated FSK in the Port menu). For additional information on setting up FSK with 2Tone, see Setting up FSK in Rttyrite for 2Tone.


MMTTY 75 baud Setup

When using either the MMTTY plug-in or XMMT.ocx support for MMTTY, changing the mode to 75 baud (100 WPM) Baudot via the Rttyrite Mode menu does not directly work.  In order to change from 45 to 75 baud when using either the MMTTY plug-in or XMMT.ocx support for MMTTY, you must change the rate in MMTTY Setup. With MMTTY running in Rttyrite, go to the Option menu and select Setup from the RTTY Control Panel.


If you are running MMTTY version 1.68A or later, in Setup, go to the Demodulator tab screen and un-check Fixes 45.45 baud as shown below.  (Note: If you are running an earlier version of MMTTY, it is highly recommended you download and install version 1.68A or later from the MMTTY page on the MM Hamsoft web site.) MMTTY versions earlier than 1.68A do not have the Fixes 45.45 baud check box. 75 baud can still be achieved; just skip this step.


Go to the Decode tab and use the BaudRate pull-down menu to select 75, then click OK.  Once you select 75 and click OK, you will then be set to send and receive 75 baud using either AFSK or FSK.  If for some reason this doesn’t work, close the MMTTY window and reopen it and you should be set to 75 baud.  Or change the TU type in Rttyrite to Dumb Terminal Unit and then go back to MMTTY and that should also set you to 75 baud (thanks Joe W4TV). For more information setting up MMTTY for FSK see either Setting up FSK in Rttyrite for the MMTTY Plug-in or Setting up FSK in Rttyrite for MMTTY via XMMT.ocx.


When you want to return to 45 baud RTTY, go back to the Decode tab screen of MMTTY Setup and select 45.45.  If it doesn’t work at first, try changing the mode in the Rttyrite Mode menu 45 baud (60 WPM) Baudot, then changing the baud rate to 45.45 on the Decode tab screen of MMTTY Setup.  Or close the MMTTY window and reopen it.

WinRTTY 75 baud Setup

To run 75 baud RTTY with WinRTTY running in the Rttyrite window, using either AFSK or FSK, simply change the Mode menu selection to 75 baud (100 WPM) Baudot.