A program for amateur radio digital communications via a sound card. Supported modes are RTTY (Baudot code), ASCII (7 or 8 bits), PSK31 (BPSK and QPSK), BPSK63, QPSK63, BPSK125, AMTOR-FEC (SITOR-B, NAVTEX), MultiFSK-16, MultiFSK-8. HF-PACKET and UHF-PACKET (AX25) are supported in KISS-TNC emulation mode. SELFEC SITOR, AMTOR-ARQ (SITOR-A) and DTMF-code decoding is also possible. No additional hardware is required. You only need a transceiver and computer (Pentium-100 or better) with a sound card. A simple circuit for PTT-control can be used. It is fast and convenient to use with many macros for transmitting. Can integrate with AALog logger.

Platform: Windows XP/Vista/7/8/10/11

The author’s program overview

The working area of the program is divided into several windows, the sizes of which can be changed by the user by dragging the borders.

In the top window the current spectrum of a signal (blue line) and a peak detector of spectral components (green line) are shown. The vertical red lines in this window show the working frequencies of the RX filters. In most modes you see two vertical line; in PSK modes - only one. To change the center frequency, click on the desired frequency (probably between the peaks). In MultiFSK mode mouse click defines lowest radio frequency, not center one.

The short thick black lines show TX frequencies. In PSK modes you see only one TX frequency. To change the TX frequency, click on the desired frequency by right mouse button (or the left mouse button with "Ctrl" key pressed).

Ruler under top window shows frequencies of sound spectrum. RX and TX frequencies and shifts are also shown in the status line.

You can use keyboard and screen buttons located below spectrogram ruler for fine tuning.
    "Alt-<" , "Alt-Left" keystrokes and "<" button move RX frequency to 1 Hz down.
    "Alt->" , "Alt-Right" keystrokes and ">" button move RX frequency to 1 Hz up.
    "Alt-Down" keystroke and "<<" button move RX frequency to 5 Hz down.
    "Alt-Up" keystroke and ">>" button move RX frequency to 5 Hz up.

These screen buttons can be used for TX frequency changing also. TX sound frequency is changed if right mouse button is used or "Ctrl" key is pressed.

The "Setup / View / Logarithmic spectrogram scale" option or Alt-Z hotkey switches the spectrogram window between a linear or logarithmic scale. Analogously, the "Setup / View / Logarithmic oscillogram scale" option or Ctrl-Z hotkey switches the oscillogram scale. The logarithmic scale is usually more convenient, but it uses more computer resources.

The "SQL" button turns squelch on. The number to the left of the "SQL" button determines the squelch threshold. When squelch is switched on, the horizontal red line shows the squelch threshold.

The "Setup / View / Spectrogram as waterfall" option or "Alt-W" hotkey switch spectrogram view to waterfall mode and vice versa. Waterfall colors can be customized via "Setup / Waterfall" options.

The "Zoom" menu and "Alt-1" ... "Alt-5" hotkeys change frequency scale of spectrogram and waterfall.
To move a visible part of spectrogram or waterfall to left or right drag it by mouse with Alt key down.

A phase indicator can be used for fine tuning in PSK modes.
It can be switched on or off via "Setup / View / Show phase indicator in PSK" option or "Alt-I" hotkey.
In ideal conditions you see immovable or slow rotating line there. Faster rotation means more frequency error.

The third from top window shows an oscillogram of the decoded signal.

The received text is displayed on the second from top window. When the RX buffer has grown to about 20kB, part of the data is moved into an invisible buffer.

The "AFC" button (auto frequency control) adjusts the long red lines (working frequencies) to the closest peak frequencies. The numbers to the left of the AFC button determines the limits of AFC. The first number is local deviation in hertzs, i.e. maximal deviation from current frequency. Second number is global deviation in hertzs, i.e. maximal deviation from last user-selected frequency. User-selected frequencies are shown at spectrogram by short red lines .

When the option "Setup / Interface / AFC at mouse click" is selected TrueTTY immediately adjusts the RX frequency to the nearest station after every mouse click on the spectrogram regardless of the "AFC" button state. But this action is not made after click on the ruler under spectrogram.

The "TxAFC" button "nets" the TX central frequency to the RX central frequency.

The mode of automatic transceiver frequency control can be switched on at the "Setup / Tuning" page. In this mode transceiver radio frequency is changed to consist RX frequency to TX frequency. Auto-tuning is made  after click on spectrogram or ruler below. Tuning can be made by RIT or by VFO according selected option. Take to attention that not every transceiver has programmable RIT. In this case auto-tuning by RIT is impossible. Tuning is made via Omni-Rig software interface ( http://www.dxatlas.com/omnirig/ ), which should be installed separately.
The Hamport software ( https://www.dxsoft.com/en/products/hamport/ ) also uses this software interface and install it automatically.

The option "Follow VFOB by VFOA with offset" is located at this page also. When it is checked, VFOB frequency is tuning to VFOA frequency with given offset automatically. This option is useful if transceiver can not use narrow-band filters in SSB mode. For example, you can receive in CW or FSK mode (with VFOA) and transmit in SSB (with VFOB).
 
The "Use Rig" box is used to select a rig controlled by Omni-Rig.

The "Show Omni-Rig Setup" button is used to activate Omni-Rig setup dialog..

With the "Reverse/Normal" button on Normal, "mark" is the higher RTTY tone; in Reverse "space" is the higher tone. This button does NOT alter the signal polarity of FSK output of the COM-port. In QPSK mode this button is used to select normal or inverted QPSK. In BPSK and AX25 modes the button position is have not meaning.
 
The "TX" button switches the transmitter on. The program transmits characters entered into the bottom window. During transmission, sent symbols change their color and are copied into the Sent window (second from bottom). When the option "Setup / View / Show sent symbols in RX window" is selected, sent text is shown in the RX window also. Transmitted text is deleted from the Input window after the "Line Feed" character is transmitted.

The "Pause" button stops transmission of previously entered text. The transmitter is left on and continuous sequence of "Letter shift" characters (in RTTY mode) or another idle characters is transmitted.

If the "Setup / Interface / Continuous carrier while idle" option is enabled, TrueTTY doesn't use idle symbols in RTTY and ASCII modes. A continuous carrier is transmitted in pauses in this case.

If the "Setup / Interface / Send whole word only" menu option is selected, TrueTTY doesn't start to transmit the next word until a space, right square bracket or line feed is entered.

The "Mode" menu selects a working mode (RTTY, ASCII-7, ACSII-8, AMTOR-FEC, BPSK31 etc.).

Signal speed and frequency shift are selected via the "Speed" and "Shift" menus respectively. Take into consideration that when you select RTTY or AMTOR mode via the "Mode" menu, speed and shift are reset to the default values 45 Baud/170 Hz and 100 Baud/170 Hz respectively. 

User can select optimal or wide filters via "Filters" menu in RTTY and ASCII modes. Wide filters can be useful to decoding signals corrupted by polar flutter. Use optimal filters in all another cases.

When AMTOR-FEC mode is selected, you can decode SITOR-B and NAVTEX transmissions also, because they are in fact the same mode. There are options "Fast Sync" and "Normal Sync" in this mode. When the "Fast Sync" options is selected, the program can synchronize with receiving signal much faster, because it doesn't need special idle characters to do it. But there is a chance of having an incorrect synchronization in that case.

To receive broadcast FEC, the "Normal/Reverse" button must be in "Normal" position in USB and "Reverse" in LSB. To receive SELFEC, switch this button in opposite position and switch on the "Fast Sync" option.

In AX25 mode TrueTTY can transmit as KISS-TNC emulator only. See details in documentations..

If your sound card can work in full-duplex mode, it can be useful to enable the "Setup / Interface / Use duplex sound card" option. In this case you can check your own transmitted signal, if your transceiver has self-monitoring capability.
 
The "F1"..."F12" buttons (and "F1"..."F12" keyboard keys) are used to transmit previously defined macros. You can use "Esc" key and Ctrl-F1...Ctrl-F12, Alt-F1...Alt-F12 combinations also. The Alt-F6 combination is available only via mouse. The number of macro buttons can be increased by the "Setup / View / Number of macros buttons rows" option.  Macros are inserted into the Input window in a place indicated by the cursor. To open the Edit Macros window, select the "Edit macros" menu. You can edit text on macros buttons there also. In turn, keyboard macros may contain special character sequences or macrosequences.
    
In particular, macrosequences can point to edit fields "Call", "Name", "RST" and "Other" located above the Sent Symbols window. The "Clear" button sets those fields to their default values. The default values are defined by parameters "CallOnClear", "RSTOnClear", "NameOnClear", "OtherOnClear" of the TRUETTY.INI file (only in the registered version).

The "Beacon" button switches on the beacon mode. In this mode Alt-F12 macro is executed periodically. The period in seconds is defined by the regulator on the left of the "Beacon" button. The shortcuts for "Beacon" button are Alt-B and Ctrl-B.
Special macrosequences can be used to switch beacon mode on and off also.

When the "Setup / Interface / Beacon off at mouse click" menu option is enabled, beacon is switched off by mouse click on spectrogram, RX window or input window or by key pressed in the input window.

The "File / Send Text File" menu command puts text from selected file into the Input window. The text can also contain macrosequences.

The "OnTop" button puts TrueTTY in front of all windows.

The menu command "File / Clear Buffer" clears the 'Received Text' window and invisible RX buffer. The command "File / Save Buffer" saves both parts of the RX buffer (invisible and visible) into a file.

The menu command "File / Open Buffer in Notepad" saves visible part of receiving buffer (about last 20 KB) in a temporary file and opens this file by a text editor. Then you can view this file or print it. The hotkey of this command is Ctrl-N.
 
The "File / Open Capture File" menu command opens a capture-file for received text. New received text is written into that file. If the file exist, new text is appended to it.
The "File / Close Capture File" command closes a capture-file. Capture-file state is shown in the status line. The hotkey for capture on/off commands is Alt-L. You can use command line arguments "/c Filename" to open a capture file at the program startup. "Filename" is name of the file to be opened.

The "File / Open KISS Capture File" command opens capture file to save all receiving AX-25 packets in the KISS-format.

The "File / Open Wave Capture File" command opens wave-file to save all sound received from soundcard. File is closed by the "File->Close Wave Capture File" command. The hotkey for these commands is "Alt-V". Take to attention that a minute of sound recording need above 1 MByte disk space.

TrueTTY has one minute sound buffer. "Replay" and "Save" buttons are used to control this buffer.
The "Replay" button click makes TrueTTY to replay previous 10 seconds of received signal.
The "Save" button writes previous 60 seconds of a sound to a wave file in the "Waves" directory.
This wave file is saved with time-stamped name (HH_MM_SS.wav) in a sub-directory with date-stamped name
(YEAR-MM-DD). For example, the file "Waves\2004-06-03\15_10_43.wav" is a piece of sound started at 15:10:43 UTC on 03 June 2004.
Special macrosequences can be used to control this sound buffer also.

The "Setup / Interface / PTT port" option is used to select the computer port (COM or LPT) for PTT interface.
The "Setup / Interface / PTT pins" option defines used pins of COM-port.

The "Setup / Interface / Produce FSK output at TxD" option enables FSK-output at COM-port in RTTY and ASCII modes.
 
If the "Setup / Interface / Tx at keyboard press" is selected, the transmitter is switched on automatically when you enter at least two characters in the Input window. If the option "Setup / Interface / RX at free buffer" is selected, the transmitter switches off automatically when no text is ready for transmitting.

The "Setup / Interface / Real input sampling rate" and "Setup / Interface / Real output sampling rate" fields are used  to correct sound card sampling rate variation against the nominal frequency (11025 Hz). These parameter mean the real sampling frequencies during recording and playback correspondingly.

The "Unshift On Space" option is switched on and off by the "Setup / Text / Unshift on space" checkbox. When this option is selected, receiving characters are switched to "Letters" after receiving "Space" or "Line Feed" character in RTTY and AMTOR modes.

Manual switching of receiving character shift can be made from keyboard. Keypad "*" or Alt-(keypad "*") is Figures and keypad "-" or Alt-(keypad "-") is Letters.

The options "Setup / Text / English charset", "Setup / Text / Russian charset",
"Setup / Text / English/Russian Extended Charset" and "Setup / Text / Swedish Charset" select the alphabet to be used in RTTY and AMTOR modes. The "Setup / Text / Extended Baudot" option switches on the extended code table (with high and low letters) for these modes.

The "Setup / Text / Backspace handling" menu option switches on "BACKSPACE" symbols handling in PSK, ASCII and MultiFSK modes.

The windows appearance can be changed via the "Setup / Fonts & Colors" options. 

Some windows and panels can be hidden by the "Setup / View / Show oscillogram window" and "Setup / View / Show edit window" options.

The program can transfer received data to AALog logger (V1.0.3 and later) and some another loggers. Data is transferred from RX-window and "Call", "RST", "Name" and "Other" edit fields. To transfer data from the RX-window, double-click on a word or select words with mouse. Then select the field from the popup-menu. When data is transferred to the logger, the same data are transferred into the appropriate edit field of TrueTTY. Data from the edit field is transferred after exiting from it.

When the "Setup / Text / Catch word by one mouse click" option is enabled, you can catch a word from RX-window by a single mouse click, not double-click but you still can select part of the text by mouse dragging.

When the  "Setup / Text / Catch words in contest mode" option is enabled, the program  doesn't use popup-menu to catch word to logger. In this case TrueTTY recognize callsign or control number automatically.

When the "Setup / Text / Copy transferred data to clipboard" menu option is enabled, data transferred to logger is also copied to the Windows clipboard.

The "Setup / Text / Use "Other" field as" option assigns an alternative meaning to the "Other" edit field. This new meaning is used to capture words from the RX window and to transfer data to the logger.

The "Setup / Other / Send Mode to logger when mode was changed" option defines if TrueTTY sends information about new mode to logger after mode changing. The "Setup / Other / Send Mode to logger together with callsign" defines if TrueTTY send information about mode to logger every time when it send callsign. The "Setup / Other / Send mode ... as ..." defines which words TrueTTY uses for each mode. If empty string is defined for mode, information about this mode is not transferred at all.

TrueTTY can decode signals from a WAVE-file. Desired file is selected by the "File / Decode From File" command.
A WAVE-file must be Windows PCM file, without compression. A sample rate must be 11025, 22050 or 44100 Hz. Preferred file parameters are mono, 16 bit, 11025 Hz.

Selected options of the program are saved by "Setup / Save" button. Options are written into the file TRUETTY.INI . The program looks for this file in the working directory. You can have several variants of the ini-file for different situations (for example, one for ordinary QSO's, and another for contests). Just create several shortcuts to TRUETTY.EXE each with a different working directory.

The number shown in the "FrB" field of the status bar means the number of free buffers for recording a signal. If it is reduced to ten or less the speed of the computer will not keep up. Try to reduce the number of simultaneously running programs or replace the computer :-).

Most of the screen buttons have keyboard shortcuts.

TrueTTY interfaces with logger software via ini-files and Windows messages.  TrueTTY can also transfer received characters to another program and get text to transmit from other software by using the DXSOFTEX.DLL library.
The "Setup / Interface / Exchange DLL channel" option selects used channel of DXSOFTEX.DLL . Default value is 1.

See https://www.dxsoft.com/dxs-exch.zip for details about program integration.

TrueTTY can emulate hardware modem or TNC using additional COM-port also. See documentations for details.

Related links

• WM2U’s review of TrueTTY.
  http://www.qsl.net/wm2u/truetty.html