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, AMTOR-FEC (SITOR-B, NAVTEX), MultiFSK-16. 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 9x/NT/2000/XP
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, which should be installed separately.
The Hamport software 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.
TrueTTY can emulate hardware modem or TNC using additional COM -port also. See documentations for details.
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