Configuring TrueTTY
for Blind and Vision-Impaired Hams

 

   This article is about setting up the TrueTTY HF digital mode program for use by blind and vision-impaired amateur radio operators. Links to articles describing the accessibility and text-to-speech feature of TrueTTY are listed at the end.

Configuring TrueTTY

   The menus are described in the TrueTTY Program Overview, which is accessible in the Help menu.

   Most settings can be entered using the Setup Menu. In addition, a couple of changes to the TrueTTY.INI file make the program more accessible for screen reader users. The .INI file saves your menu settings and is enabled when you register the program. It is in the Windows ProgramData folder, which is hidden by default. A typical location is C:\ProgramData\TrueTTY\TrueTTY.INI. The file opens in a text editor, usually NotePad. Before editing, save a copy of the original (File → Save As) with a different name.

   While you can change some parameters using the other menus and the Control bar near the top of the program window, those changes do not persist when the  program is restarted.

   In this article the vision-related settings are grouped as follows:

          • Information about the radio/computer interface.
          • How do you want to tune the radio?
          • Do you use high visibility text?
          • The mode you plan to use most often (RTTY, PSK, etc).
          • Manual transmit switching for screen reader users.
          • Macros.

Step 1: Setup Menu—Interface Tab

   Data Exchange Port:  Enter "None." This TrueTTY port is used for advanced applications such as External Modem Emulation (described in the Help Menu).

   PTT Port Configuration:  This entry depends on the type of Transmit/Receive switching you use. The options in the pull-down menu are described in "Connecting Sound Card With Transceiver" in the Help Menu. The author gives an example of a simple switching circuit. Or, if you use the radio VOX for switching, the PTT port type is "None." The settings for an external USB sound card interface are in the Appendix of this article. The WM2U web site has other examples of interfaces.

Step 2:  Setup Menu—MOX Tab

   It is convenient to have TrueTTY transmit automatically when you start typing and stop when all the text is sent. Configure this by clicking on the MOX Tab in the Setup Menu. (MOX refers to manual transmit switching.)

   Select "TX at keyboard press" and "Rx at free buffer."

Step 3:  Tuning

   The tuning method most commonly used by sighted hams is to view the waterfall display and tune the TrueTTY audio frequency filter.

   If using the waterfall is not an option, it's best to use a radio with a narrow bandwidth and tune the radio VFO manually. In that case, you can tune to a quiet spot on the band and call CQ.

   The center frequency of the radio receiver pass band (displayed on the TrueTTY waterfall) is at the offset frequency 1500 Hz. To set the TrueTTY default receive and transmit frequencies to the center of the passband, edit the TRUETTY.ini file (in the TrueTTY folder in ProgramData) to the values RxFrequency=1500 and TxFrequency=1500. The left column in the following table shows the AFC settings to use in the .ini file. The entries in the column on the right are explanations and should not be entered in the file.

     AFC On=1              (AFC on.)
     TxAfc=1                  (Lock Tx frequency to Rx frequency.)
     AFC_Speed=1        (=1 Sets the Local AFC deviation=5 Hz.)
     AFC_Limit=5        (Global AFC deviation=5 Hz.)

   If the radio VFO tuning is precise enough, you may be able to tune in other PSK (but not RTTY) stations by listening to the received audio. You must be within 1 Hz for accurate decoding of PSK. A narrow receiver filter is also required—to isolate the audio from a single signal and to prevent strong nearby stations from desensitizing the receiver.              

Step 4:  Setup Menu—Fonts and Colors

   The Fonts and Colors Menu has a wide range of fonts, styles, sizes, font colors, and background colors. A preview box shows the result of each selection. Examples of TrueTTY high visibility text are shown in a separate article.

Step 5:  Mode

   The operating mode can be changed using the Mode Menu, but it reverts to the default when the program is restarted. The default mode is saved in the .ini file, eg Mode=0 for RTTY and Mode=1 for PSK31.

Step 6:  TrueTTY Macros

   The rules for macros are described in the Macrosequences chapter of the Help Menu, and the editor is in the Edit Macros Menu. The default template for the F1 macro calls CQ. Enter your call sign in the F4 macro box. The F12 macro clears the Transmitted Text Box.

For More Information

TrueTTY Text-to-Speech
TrueTTY Accessibility

Appendix: Using an External USB Sound Card

   These are the TrueTTY settings for an external USB sound card interface, a MicroHam USB Interface III. Using the MicroHam software, PTT is assigned to a virtual serial port (eg, COM9):

     PTT port type: COM-Port.
     PTT port number: COM9.
     Input sound card number: 0 Microphone (3-USB Audio Codec).
     Output sound card number: 1 Speakers (3-USB Audio Codec).
     Data exchange port: None.
     All other settings=default values.
     In most cases, the radio CAT control port is not used by TrueTTY.

Author Information

   Peter DeNeef, AE7PD, is an Extra Class amateur radio operator in the U.S. This web site has no ads or conflicts of interest.
Email:  HamRadioAndVision "at" gmail "dot" com.

rev. 4/16/2012

                         HamRadioAndVision Home Page