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2.7.4 Digital - MMTTY for RTTY support

The MMTTY soundcard interface, which uses the MMTTY engine by Makoto Mori, JE3HHT, is the most popular method for RTTY. Amateurs who use RTTY are indebted to Mori-san for the positive impact MMTTY has had on amateur radio RTTY.

The 2Tone soundcard interface was written by David Wicks, G3YYD, as a replacement for the MMTTY interface in programs like N1MM Logger. It can be substituted for MMTTY as the digital engine used in any of the Logger's DI windows or Additional RX-only windows. The 2Tone windows are different in appearance from the MMTTY windows, but perform similar functions. These windows are described and documented in pdf files that you download with 2Tone.

1. MMTTY Windows

When using MMTTY two windows will open.

  • the Digital Interface window
    • is similar for MMTTY, MMVARI, Fldigi and external Interfaces (TNCs or TUs). See the Digital Interface section
  • the MMTTY engine window -
    • there are four versions which can be selected in the Digital Interface menu under Settings.
      • Small version MMTTY engine window

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      • Normal, or Large version MMTTY engine window

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      • Control Menus - small window plus the menu bar (View, Option, Profiles)

      • Control Buttons - large window minus the menu bar

2. Download, Configure and Test MMTTY

2.1. Download MMTTY

  • Download the current release of MMTTY here
    • At least version 1.64 is needed; version 1.68A is recommended
  • Run the setup program and install MMTTY to your computer in its own directory
    • In Windows 7, 8 and Vista, you must install MMTTY to somewhere other than the Program Files or Program Files(x86) directories (for example, you can create an installation folder such as C:\MMTTY or C:\HamRadio\MMTTY)
    • If you are using a standard USB-to-serial adapter for FSK keying, you will probably need to use the EXTFSK plug-in. You can find a link to EXTFSK on the MMTTY download page (near the bottom of the page). Go to the EXTFSK page, then download the ExtFSK106.zip file from the link at the bottom of that page and unzip it into the MMTTY program folder
      • Users with high-performance multi-core CPUs (typically a 2.4 GHz i5 or faster Intel based system or 2.4 GHz quad core or faster AMD based system running Windows 7 or Windows 8) may be able to use EXTFSK64 instead of EXTFSK. EXTFSK64 has improved timing relative to EXTFSK, it supports speeds other than 45.45 baud, and it can be used with LPT ports on 64-bit systems, but its CPU requirements are much greater than those of EXTFSK. See http://www.qsl.net/ja7ude/extfsk/indexe.html for more information and downloads
    • When you run MMTTY from inside N1MM Logger+, you will likely want the MMTTY configuration to be different from the configuration used when MMTTY is run stand-alone. MMTTY always saves its configuration data to files within its program folder. Therefore, any copy of MMTTY that is used from within the Logger should be stored in a different folder from the main MMTTY folder. This can be a separate sub-folder in the MMTTY program folder, or it can be a folder in the N1MM Logger+ user files area, which is normally in your My Documents folder (e.g., you can create a DigitalEngines sub-folder in the Logger+ user files area and then create separate subfolders in that folder for each copy of MMTTY you wish to run from within the Logger). Then copy only the following files from the main MMTTY program folder into the new folder: MMTTY.exe, MMTTY.ini, UserPara.ini, and if you need it for FSK transmitting, Extfsk.dll or Extfsk64.fsk. If you use more than one copy of MMTTY (e.g. for SO2R/SO2V, or for additional RX-only windows), each copy must be installed in its own folder

  • The 2Tone engine, which can be used as a drop-in replacement for MMTTY, can be downloaded from the G3YYD folder in the Files area of the N1MMLogger-Digital Yahoo user group, in the form of a zip file containing the 2Tone engine together with documentation for installing and using it. Each copy of 2Tone you plan to run (from DI windows or additional RX-only windows) must be placed in its own folder

2.2. Configure MMTTY

2.2.1. FSK KEYING

1. In the N1MM Logger Entry window, select >Config >Ports, Telnet Address, Other >Digital Modes tab

    • Select Soundcard as your Interface type
    • Select for the selected Digital Interface as MMTTY, Mode FSK
    • Select the path to your MMTTY directory (for DI-2 if you are configuring for the second DI window)
  • Select the 'Hardware' tab
    • Beside the port that you are using for FSK keying, if you are also using this same port for PTT or CW keying from the main N1MM Logger program and the CW/Other box for that port is checked, place a check mark under the Digital column beside this port as well; note that this is not applicable if you are using EXTFSK or EXTFSK64. If you are only using the port for RTTY and not in other modes (i.e. the CW/Other check box is not checked), you do not need to check the Digital check box
    • If you have checked the Digital check box, click on the Set button and set the Dig Wnd Nr to 1 (or 2 if you are configuring for DI-2)


2. Save and exit the Configurer

  • If MMTTY is already loaded you may get an error message about not being able to open port xxxx. This is not a problem at this point; note that you can always re-initialize MMTTY by closing and re-opening the Digital Interface window


3. Open the Digital Interface window (under the Window menu)

  • Select the Interface > MMTTY menu item in the DI window
  • Select: Option > Setup in the MMTTY window, or use the DI window's Setup > Setup MMTTY menu item
    • Select the TX tab and under PTT, set the serial port that you will be using for FSK keying; if you also use this port in other modes for CW or PTT keying, the Digital and CW/Other check boxes in the Configurer should also be checked for this port, and the DigWndNr in the setup dialog box for that port must indicate which DI window the port will be used with (1 or 2)
      • If you are using a control line other than TxD for FSK keying, you must select EXTFSK or EXTFSK64 as the serial port and configure the port and signal line information in the EXTFSK window. If you are using a USB-to-serial adapter, you will most likely also have to select EXTFSK or EXTFSK64 as the serial port and configure the port and signal line information in the EXTFSK window, as most USB-to-serial adapters are not capable of keying FSK RTTY without EXTFSK
      • Note that MMTTY's Radio Command port must be set to NONE; if you use MMTTY's Radio Command port when running MMTTY stand-alone, you must reconfigure MMTTY not to use this port when it is run from N1MM Logger+
    • Select the Misc tab in the MMTTY Setup window and check COM-TxD(FSK) for the Tx Port
      • If you are using a USB device to do FSK keying, click on the USB Port button and set the option to C. Limiting Speed
    • Select the Sound Card tab (in MMTTY version 1.66G or later) and choose the correct sound card for Reception (the Transmission sound card is not used in FSK) (Note: Users of newer versions of Windows should consult the text box on sound card selection in Windows 7 in the section below on AFSK, as the same issues may apply to sound card selection for reception in FSK.)
    • If you are using two copies of MMTTY to decode signals using the two channels of a stereo sound card for different receivers (SO2V) or different radios (SO2R), select the Misc tab again and in the Source pane, select either "Left" or "Right", depending on which channel you want this copy of MMTTY to decode
    • Close the MMTTY Setup dialog
    • Close the Digital Interface window to have the Logger and MMTTY save the settings

2.2.1.1. Using the RIGblaster Interface for FSK with N1MM/MMTTY


The default for FSK via MMTTY is TXD. You'll need to change the jumpers when using a RIGblaster. Also, make sure you get MMTTY working as a standalone first. Then you should just be able to specify MMTTY (select Soundcard) in the Digital Interface config in N1MM and it should take off.

2.2.2. AFSK KEYING


1. Open the Configurer (Configure Ports, Telnet Address, Other in the Config menu).

  • Select the Digital Modes tab
    • Select Soundcard as your Interface type.
    • Select for the selected Digital Interface as MMTTY, Mode AFSK
    • Select the path to your MMTTY directory (for DI-2 if you are configuring for the second DI window)
  • Select the 'Hardware' tab
    • You can let N1MM Logger+ control PTT, or if you don't use PTT in other modes and want to have MMTTY control PTT, you can configure MMTTY to control PTT from a serial port. You can time-share a serial port between CW/PTT keying in N1MM Logger+ and PTT from MMTTY; to do this, you must place a check mark under the Digital column beside the port that you are using for the digital port
    • If you are using VOX or an external VOX unit like the SignaLink interface to control PTT, you don't need to configure anything for it in the Logger
    • If you have checked the Digital box, click on the Set button and set the Dig Wnd Nr to 1 (or 2 if you are configuring for DI-2)
    • If you are using 2Tone in place of MMTTY, do not check the Digital check box for your PTT port


2. Save and exit the Configurer.

3. Open the Digital Interface window (under the Window menu)

  • Select the Interface > MMTTY menu item in the DI window
  • Select: Option > Setup in the MMTTY window, or use the DI window's Setup > Setup MMTTY menu item
    • If you are using 2Tone rather than MMTTY, you will make the configuration settings below in the 2Tone Setup window, which is opened from the 2Tone window
    • If you have chosen to have MMTTY control PTT (not applicable with 2Tone), select the TX tab and under PTT, set the serial port that you will be using for PTT. If the port is being time-shared with other modes, this should be the same port that you checked the Digital box for in the Configurer
      • Note that MMTTY's Radio Command port must be set to NONE; if you use MMTTY's Radio Command port when running MMTTY stand-alone, you must reconfigure MMTTY not to use this port when it is run from N1MM Logger
    • Select the Misc tab and check Sound for the Tx Port
    • Select the SoundCard tab (in MMTTY version 1.66G) and choose the correct sound card for both Reception and Transmission (users of WIndows 7, Vista and newer versions should read the note below)
    • If you are using two copies of MMTTY to decode signals using the two channels of a stereo sound card for different receivers (SO2V) or different radios (SO2R), select the Misc tab again and in the Source pane, select either "Left" or "Right", depending on which channel you want this copy of MMTTY to decode
    • Close the Setup dialog

    • Close the Digital Interface window to have the Logger and MMTTY save the settings


Sound Card Selection in Windows 7, 8 and Vista

In earlier versions of Windows, selecting the sound card was relatively straightforward. Windows assigned a number (or two numbers, one for recording=receiving and one for playback=transmitting) to each sound card device when it was installed, and that number could usually be relied upon not to change. Once you had selected the desired sound card in MMTTY, you were finished with the sound card configuration.

Starting with Vista and continuing in Windows 7 and 8, Windows has made life for sound card users more complicated. The list now enumerates each active input or output as a separate device. The list of active inputs or outputs can change dynamically. Plugging or unplugging a cable into one of the jacks on a sound card can create or delete a new entry on the list. Windows power management can turn a USB port off if it has not detected any keyboard activity for some time, causing any inputs or outputs on a USB sound card on that port to be removed from the list. When the computer is restarted or reawakened after hibernating or sleeping, the list may be reconstructed and if there have been changes since the last restart, the order of devices on the list may change. If you are using a radio with a built-in USB codec, turning the radio on or off will add or remove that codec to/from the list. If any of these changes in the list results in a different number being assigned to a device you are using in MMTTY, that device will appear to stop working and you will have to readjust the sound card configuration in MMTTY.

If this happens to you, the way to avoid it is as follows: Immediately before the contest, make sure that every sound card or codec that you plan to use during the period of the contest is turned on and stays on for the duration. Verify your sound card configuration immediately before the contest and then avoid doing anything during the contest that might result in a change to the list. Disable power management features that might result in a USB port you are using being shut off by Windows. If you are using the USB codec inside a radio, always turn on the radio before opening the DI window, and close the DI window before turning off the radio; preferably, don't turn the radio off during the contest. Fortunately not all of these precautions will be necessary in every case, but you should be aware of the possibility just in case.

One other wrinkle introduced in newer versions of Windows is that with some sound cards, the default for the sound card input in the Windows Control Panel may have been set to single channel (mono) instead of two channels (stereo). If you are planning to use both channels of a stereo sound card to decode signals from two receivers (SO2V) or two radios (SO2R), you may need to verify that the default recording format for that sound card input is set to two channels. This is done via the Windows Control Panel (Sound > Recording > select the input you are using and click on Properties > Advanced)

While you are checking the default recording format for number of channels, you will likely also have the choice of setting the sample rate and bit depth. Bit depth is not a problem (16 bits is fine), but the sample rate has become an issue in Windows 7, 8 and Vista. The sampling speeds in all applications that are using the same sound card in parallel should be the same, and they should be integer sub-multiples of the hardware sampling rate. The default sampling speed in MMTTY is 11025 Hz, which is suitable for a sound card that is set for CD quality (44100 Hz). However, the sampling speed in 2Tone is 12000 Hz, which is suitable for a sound card that is set for DVD quality (48000 Hz), and it is not user-adjustable. Your best bet is probably to set the sound card's sampling rate to 48000 Hz (DVD quality), and to change the sampling speed in MMTTY to 12000 Hz (MMTTY Setup window, Misc tab, lower left corner - it's called "Clock").

3. Testing MMTTY

MMTTY is also a stand-alone application, so testing can be done outside N1MM Logger+. You can use the originally-installed copy of MMTTY for stand-alone testing. Configuration changes you make in the stand-alone copy will not be applied to the copies that you run from inside the Logger; once you have settled on a setup item in one copy, if you want that same item to apply in other copies you will have to use the Setup window from within each separate copy to change that item.

4. Dual Receiver/Dual Radio Setup

In a dual-receiver setup (SO2R or SO2V), you may wish to be able to copy two separate RTTY signals (e.g. on two separate bands or two separate frequencies) simultaneously. To do this, you would open two Entry windows (VFO A/Radio 1 and VFO B/Radio 2) and open the Digital Interface window from each Entry window. You can then run MMTTY (or other digital interface engine, such as 2Tone) from each of these DI windows.

The two audio streams from the two receivers can either be decoded by two separate sound cards, or in a single stereo (two-channel) sound card using the left and right channels for the two receivers. In either of these situations, the two copies of MMTTY must have different configurations; in particular, each one must be configured to use a different channel of the sound card, or a different sound card. In the case of a dual radio setup, if you are using FSK on both radios and/or if MMTTY is used to control PTT on both radios, each copy of MMTTY would also have to have access to its own serial port for PTT & FSK. This is also true in SO2V setups in order to enable transmitting from either VFO; even though there is only one FSK keying input to the radio in SO2V, the two DI windows need two separate serial ports for FSK keying, both connected to the same keying input on the radio.

These serial ports are configured in MMTTY. You must set up each copy of MMTTY to use its respective serial port by choosing the relevant serial port in the PTT & FSK Port box under the TX tab in the MMTTY Setup window. If one or both of these ports is time-shared with N1MM Logger+ for CW/PTT keying, then in the Configurer you must indicate this with check marks in the Digital column (Note: in order to check two Digital mode ports in the Configurer, you must be in SO2V or SO2R mode). You must also click on the Set button for each port in the Configurer and set the Dig Wnd Nr to 1 or 2, to indicate which of the two DI windows that serial port will be associated with.

If the two copies of MMTTY are to use different channels of the same sound card, each copy must be configured to use its respective channel on the sound card under the Misc tab in the MMTTY Setup window; or, if they are using different sound cards, each copy must be configured to use its own sound card under the SoundCard tab.

In order to support separate configurations for the two copies of MMTTY, each copy must be located in a separate folder. You can either use the main MMTTY program folder for one copy and a separate subfolder for the other copy, or you can create two subfolders for use by the Logger, leaving the copy in the main MMTTY program folder for stand-alone use. These subfolders must each contain, at a minimum, a copy of the MMTTY.exe file and the UserPara.ini file from the main MMTTY program folder. A copy of MMTTY.ini will be created the first time MMTTY is run from the folder if it was not previously present. If you are using the EXTFSK plugin, you will need a copy of the extfsk.dll file in the folder as well (or the extfsk64.fsk file if you are using EXTFSK64). Other files from the main MMTTY program folder are not used.

The Logger's DI windows have an additional RX window feature as well. Up to four additional RX-only windows can be invoked from the Setup menus in the two DI windows. They can use either hardware decoders, MMTTY or 2Tone, but the most common use is for separate copies of MMTTY or 2Tone using different decoding algorithms or profiles on the same data stream. Because they are receive-only, these windows do not need access to serial ports and are not configured in the Configurer. However, to be fully useful, although they most likely will share the same sound card and channel with their parent DI window, they do need to have separate setups from the main copy of MMTTY (e.g. to use a different decoding algorithm or profile). Therefore, if you wish to use these additional RX-only windows with MMTTY, you will need to create additional folders, one for each additional window, containing copies of the MMTTY.exe, MMTTY.ini and UserPara.ini files (or if your are using 2Tone in stead of MMTTY, the 2Tone.exe, MMTTY.ini and 2Tone.ini files). These additional folders do not have to be created at the time you first install MMTTY, i.e. you don't need to do this until you are ready to use the additional RX windows. In Windows 7, 8 and Vista, all of these folder must be outside the Program Files and Program Files(x86) paths.

5. Using MMTTY

  • Messages must begin and end with {TX} and {RX}; these macros tell MMTTY to perform PTT switching
  • There is no special abort macro needed for use with MMTTY; just using the ESC key will stop transmitting
  • The TX and RX buttons in the DI window can be used for free form typing in the TX window pane of the DI window

5.1. How to Tune RTTY

  • Use the VFO on your radio and dial in the peaks to match the 2 yellow lines on the spectrum
  • Click view and the X-Y scope to see a crossed-ellipses tuning display
    • If the X-Y display seems to rotate in the wrong direction, open the MMTTY Option > Setup window (or the DI's Setup > Setup MMTTY menu item), select the Font/Window tab and check (or uncheck) the Reverse rotation button
  • Make sure you click the "HAM" button to set MMTTY to the correct mark and shift settings
    • The default values for the HAM setting can be changed under the Demodulator tab in the MMTTY Option > Setup window
  • It's better to turn AFC off when you are in a crowded section of the band and manually tune the signals; if you leave AFC on, nearby strong signals may pull the tuning away from the signal you want to copy
  • Also in crowded sections it can be helpful to use the built-in notch and bandpass filters
  • If you are using AFSK, unless your radio has a specialized mode for AFSK RTTY, the conventional choice with MMTTY is to use LSB on all bands
    • If you use USB, make sure you click the "Rev" button in MMTTY
  • If you are using FSK, you need to be aware that NET does not work, and that tuning in a received signal by clicking in the waterfall or by allowing AFC to tune in the signal will result in your receive frequency being different from the transmit frequency. The "HAM" button will restore the correct audio frequency in your receive decoder but without retuning the radio. The "Align" button in the DI window can be used to retune your radio so that the received signal is lined up with your radio's transmit frequency

5.2. When Should I Use AFC?

  • Use AFC (automatic frequency control) when MMTTY should automatically track the incoming RTTY signal. The best example of this is when you are CQing and want to tune in off-frequency callers
  • With AFC and NET both turned on, MMTTY will track the incoming signal and also keep your transmitter frequency locked to the received signal when using AFSK (NET does not work in FSK)


When MMTTY is set to transmit FSK, AFC will work on receive only. When in "Running" mode, you want to keep your TX frequency stable, but with RX AFC set on you can pick up stations who reply a bit off your frequency and copy the exchange without losing your TX spot. Just don't let the AFC spread get too far from where you're transmitting.

  • A nice option to use is: AFC On/Off with CQ - If set then the AFC will turn on with CQ message or TU messages. This way when Running the AFC is on and during S&P the AFC is off

5.3. When Should I Use the NET Option: NET On/Off with Run Change


NET only operates in AFSK. If you are using FSK, your transmit frequency is fixed by your transmitter, and the NET software feature does not work.

  • When in 'Search and Pounce' mode the program will check the NET option so that once you tune a signal in, you will transmit on the same frequency you are receving him on (Warning: this doesn't work in FSK)
  • When in 'Running' mode the program will uncheck the NET option, which allows your receive decoder to follow an off-frequency caller while still leaving your transmit frequency unchanged

5.4. Why to Use "Auto Update TRX Offset w/Mark Freq."


If you are using FSK RTTY, most radios display the actual mark frequency on the tuning dial. A few even do this in AFSK RTTY. If your radio is like this, you don't need to use this option. The DI window title bar may display an offset frequency (radio dial (+/-) audio), but if this option is turned off the offset frequency will not be logged and you can ignore it.

If you are using AFSK RTTY, especially with the radio in LSB or USB mode, as well as when you are doing a sound card digital mode like PSK (using MMVARI or Fldigi), the radio probably displays the suppressed carrier frequency on its dial. This is different from the mark frequency. If you are using the default mark frequency of 2125 Hz, the radio's dial display will be 2125 Hz too high (LSB) or too low (USB) as compared with the actual mark frequency. By checking this option, N1MM Logger will perform the correction automatically and display the actual mark frequency in the Entry window and the Bandmap window, as well as in the DI window title bar.

5.5. Using MMTTY for 75 baud RTTY

There are some RTTY contests that specify 75 baud (100 wpm) RTTY instead of the usual 45.45 baud (60 wpm) speed. MMTTY can be used for 75 baud RTTY, but there are a few quirks:

  • If you use EXTFSK for FSK keying (e.g. via a standard USB-to-serial adapter), you will not be able to use this combination for 75 baud. EXTFSK does not support 75 baud. Instead, you must reconfigure for AFSK
  • If your CPU is capable of running EXTFSK64, it can be used in place of EXTFSK. EXTFSK64 supports 75 baud; see http://www.qsl.net/ja7ude/extfsk/indexe.html for information on EXTFSK64
  • In the MMTTY Setup window, select the Decode tab, and at the top of the window, for BaudRate select 75
  • If you are using MMTTY version 1.68 or newer, in the MMTTY Setup window under the Demodulator tab, in the section labelled HAM Default, UNcheck the "Fixes 45.45 baud" check box
  • If you are using an older version of MMTTY, you will need to be aware of the following:
    • The pre-version 1.68 MMTTY HAM Default button cannot be used in 75 baud RTTY; if you press HAM, the speed will be reset to 45.45 baud. Besides not pressing the HAM button in the MMTTY window, there are a couple of other setup items you need to take care of:
      • In the DI Setup window, under the General/MMTTY Setup tab, make sure the following item is NOT checked:
        • (MMTTY)Send HamDefault on Run to S&P Change (if you forget to uncheck this item, you will be switched back to 45.45 baud every time you switch from Run to S&P)
      • If you are using FSK with a true serial port or with an interface that supports FSK without using EXTFSK (e.g. a microHAM microKeyer), turn AFC off in the MMTTY window, and make sure the following item in the DI Setup window is NOT checked:
        • (MMTTY - MMVARI)Turn AFC On/Off on Run Change (if you forget to uncheck this item, AFC will pull your receive frequency off your transmit frequency and you will be unable to use the HAM button to correct the situation)
        • In the DI Window's Setup menu, UNcheck AFC On/Off with CQ (same reason)
      • If you are using AFSK and like to use AFC, you may continue to do so, provided you are careful to ensure that your transmit and receive frequencies stay together. The HAM button is not available to re-align your transmit and receive frequencies. Therefore if you are using AFC, you should have NET on as well, to keep your transmit and receive frequencies together. (Note: NET does not work in FSK)
  • After the 75 baud contest is over, be sure to restore the 45.45 baud speed and any of the other configuration options you changed for 75 baud, in order to restore normal functioning


Last Modification: 19 June 2014 11:55:13 EDT by VE3KI.