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1.4 Digital Installation and Setup

1. Need-to-Know about Setting Up for Digital Modes

In order to communicate in digital modes (RTTY, PSK, or other sound card digital modes), N1MM Logger+ can either use a computer sound card or an external device called a "terminal unit" or a multi-mode TNC. Terminal units and TNCs are relatively rare nowadays, and most digital communications now use a computer sound card.

The Logger uses the sound card for digital modes via a separate process called the "digital engine". One digital engine, MMVARI, is pre-loaded when N1MM Logger+ is first installed. MMVARI can do RTTY, PSK31, PSK63, and a few other digital modes that are not often used in contests. The Logger also supports several other digital engines, including MMTTY, 2Tone and Fldigi, but these engines are not pre-installed; they must be downloaded and installed separately. MMTTY and 2Tone can only be used for RTTY, whereas Fldigi supports a wide range of digital modes, most of which are not used for contesting.

Configuring a digital engine is done within N1MM Logger+ in a few places, including the Configurer (Config >Configure Mode Control, Audio, Other) as well as in the Digital Interface window. The digital engines (MMVARI, MMTTY, 2Tone and Fldigi) also have their own configuration menus that need to be set up. If you are familiar with digital modes and are moving to the Logger from some other program, you might want to proceed directly to the setup instructions in the sub-sections below. If you are new to digital modes, you can find more information on RTTY and PSK in the General RTTY and PSK Information page in the Digging Deeper part of the N1MM Logger+ manual. RTTY is particularly complex for someone coming to it for the first time; there is an excellent introduction to RTTY on AA5AU's web pages that is recommended reading for anyone starting out in RTTY.

A few notes about hardware connections for sound card digital modes (using MMTTY, 2Tone, MMVARI or Fldigi) follow. These depend on the radio, the sound card and the interface (if any) in use, and it is impossible to cover all of the possibilities in detail, but the following general comments apply:

First, you must have some means of connecting the radio's audio output to the sound card's input. The ideal connection would be from a fixed-level ("line out") output on the radio to a "line in" input on the sound card. If your radio has one receiver, this will probably use the left channel of the sound card; with dual receivers, the second receiver may use the right channel. If your sound card does not have a line level input, you may need to use a microphone input, and in this case you may need an attenuator to reduce the line level output from the radio to the lower level needed for the microphone level input on the sound card.

To transmit, there must be some means to convey modulation from the computer to the radio. For FSK RTTY, this is an on-off keying signal, which is normally generated by a serial port connected to the radio's FSK keying input through a simple keying circuit. This serial port cannot be the same port that is used for radio control or for a Winkeyer or other serial device. If it is a standard USB-to-serial adapter, FSK from MMTTY will require the EXTFSK or EXTFSK64 plugin. If you are using MMVARI for RTTY using FSK keying, select the appropriate plugin (FSK8250 for true serial ports, EXTFSK or EXTFSK64 for USB-to-serial adapters) in the Configurer under the Digital Modes tab). Fldigi can only do FSK keying with the help of an external circuit that converts the audio signals from these programs into an on-off keying signal.

For AFSK RTTY and for all other sound card digital modes (e.g. PSK31), there must be a connection from the sound card's output ("line out", or speaker or headphone output) to the radio's audio input. If the only audio input on the radio is a microphone input, you may need attenuation to reduce the level to avoid overdriving the transmitter.

You also need some means to control TX/RX switching (PTT). The most common method is to use hardware PTT control from a serial or parallel port via a simple keying circuit. Hardware PTT can be controlled either from the digital "engine" (MMTTY, MMVARI or Fldigi), or from N1MM Logger+ itself. To use serial port PTT from the digital engine, you must use a different port from the one that is used by the Logger for radio control. If you have a serial port set up for FSK keying, you can use a control line (RTS or DTR) on this same port for PTT control from the digital engine.

If you do not have a separate serial or parallel port available for PTT in digital modes, you can control PTT directly from the Logger. For example, if your radio control interface supports PTT using RTS or DTR on the radio control serial port, you can configure the Logger to use this method. If no method of hardware PTT control is available and if your radio supports PTT via radio command, you can use software PTT control from the Logger. Warning: Using both software and hardware PTT control at the same time can cause problems; do not use both methods in parallel.

As an alternative to hardware and software PTT control, you may be able to use VOX. This does not work with all radios, it cannot be used for FSK RTTY, and setting of audio levels and VOX triggering levels can be tricky, but some users have found this to be the simplest method of PTT control, since it does not require any additional hardware connections. Some external interfaces (e.g. SignaLink) perform a VOX function external to the radio, i.e. they generate a hardware PTT signal based on the presence of an audio signal without any connection to a serial port on the computer. If you are using such an interface, or VOX within the radio, you do not configure any PTT in the Logger or in the digital engine, as PTT control in these cases is external to the software.

2. Setting up N1MM Logger+ for Digital Modes

First, make sure you are familiar with basic operation of N1MM Logger+ in CW and SSB. It's not a good idea to try to use the program in digital modes if you aren't familiar with at least the basic operation of the program.

Once you are ready to begin, decide which digital engine(s) you want to use - an external TU/TNC, MMTTY, 2Tone, MMVARI or Fldigi. One of these (MMVARI) is built in to the Logger, but the others all will need to be downloaded. Each digital engine used by the Logger stores its configuration information in the directory the engine is run from. For that reason, you should create a separate directory for each copy, separate from the directory you use when you run it stand-alone or from some other logging program. If you use more than one copy of a digital engine (for example, for SO2V or SO2R, or for additional RX-only windows), you need a separate directory for each copy. For more detailed information, check out the sections on Downloading and Installing MMTTY/2Tone/Fldigi in the Digging Deeper part of the manual

After these preliminaries, start N1MM Logger+ and open the Configurer (Config > Configure Ports, Audio, Mode Control, Other). Make sure the Hardware tab is selected (this is the tab the Configurer starts up in by default).

In what follows, it is assumed that you already have radio control, CW keying and PTT control configured and working, and what you are trying to do is add in the capability for digital modes.

In many cases, especially if you are planning to use AFSK, you will already have PTT control configured from the Logger. If the same method you use in other modes is acceptable for digital modes, you don't need to do anything special about PTT for digital modes. If you are planning to use FSK for RTTY, you will be setting up a serial port for FSK keying from within the digital engine, and you can use that same serial port for PTT control in RTTY. If you are using VOX (or an external VOX such as a SignaLink), you do not need to configure PTT control in the Configurer.

All that being said, there are two cases where you need to do something about PTT control for digital modes in the Configurer. The first is if you plan to use MMVARI as your digital engine, and you want to use a control line from a serial port for PTT control. In that case, you must designate that serial port in the Configurer, check the Digital check box for that port, set the appropriate control line (DTR or RTS) for PTT, and set the DigWndNr to 1 (or 2, for the second DI window in SO2R/SO2V). The second case occurs if you are using a single serial port interface for both CW/PTT keying in CW/SSB, and also for FSK keying in RTTY. In that case you must check both the Digital and CW/Other check boxes for that port, configure DTR and RTS for CW/SSB, and set the DigWndNr to 1 (2 for the second DI window in SO2R and SO2V).

Next, you need to select the Digital Modes tab in the Configurer. First, set the TU Type to Soundcard (unless you happen to be using a hardware TU/TNC). If your main digital engine is MMTTY or 2Tone, then under DI-1 MMTTY Setup, select AFSK or FSK as appropriate for your setup and set the MMTTY Path to point to the copy of MMTTY.exe or 2Tone.exe you will be using with the Logger. If you will be doing SO2V or SO2R, repeat for a separate copy of the digital engine under DI-2 MMTTY Setup. If you will be using Fldigi, there are separate places to enter the paths to Fldigi.exe. For all of these, it is recommended that you do not try typing in the path directly. Instead, click on the Select button, which opens a standard Windows file Open dialog window, and then navigate till you find the desired .exe file and select it.

Once the paths to the digital engines are set up, select the Mode Control tab in the Configurer. On the right side, beside RTTY, set the Mode sent to radio - this should be RTTY if you are using FSK, but if you are using AFSK, it should be either AFSK (if your radio offers a separate mode for AFSK RTTY), LSB (for most radios with MMTTY or 2Tone), or USB (for Fldigi).

This completes the basic steps in the N1MM Logger+ Configurer. For more detailed explanation of the various options available, see the Configurer section of the manual.

Back in the main Entry window, if you have not already done so, choose a contest type that allows digital modes (i.e. not a CW- or SSB-only contest), and set the Mode Category in the Contest Setup window to one that includes RTTY or Digital (don't choose MIXED - that's for CW+SSB only; choose MIXED+DIG instead). Type RTTY into the call sign box and press Enter. This should open the Digital Interface window. If it does not, use the Window > Digital Interface menu item to open the Digital Interface window (in SO2R/SO2V, each Entry window has its own Digital Interface window that opens from that Entry window's menu). If your preferred digital engine does not open (e.g. if you see the MMVARI window when you wanted MMTTY), then in the Digital Interface window use the Interface menu item to switch to the digital engine you want to use (use the MMTTY menu setting for both MMTTY and 2Tone).

Select the Setup > Settings menu item in the Digital Interface window. Under Preferred RTTY Interface, select your preferred digital engine. Under Alignment Frequency, enter your preferred Mark audio frequency (e.g. 2125 Hz). If you are using MMTTY, then under MMTTY Window Settings, select either Normal or Control Menus, in order to have easy access to the MMTTY setup window. When you have completed the setup in the Digital Setup window, click on Save Configuration.

There are a host of other options in the Digital Interface and Digital Setup windows. A complete reference manual for the menu options in the DI window, the Digital Setup window and the main DI window is here.

You're not done yet. Now you have to complete the configuration inside the digital engine itself. This is especially important for FSK, since the configuration of the FSK port is carried out inside the digital engine, not in the N1MM Logger+ program. There are separate chapters in the Digging Deeper part of the manual for MMTTY, MMVARI, Fldigi, and TNCs/TUs. There are too many possibilities to cover here, so consult the chapter(s) appropriate to your situation and complete the setup as described there.

Last Modification: 23 August 2015 14:44:29 EDT by VE3KI.