cocoaModem Accessibility
(Mac OS X)


  CocoaModem is a Mac OS X modem program for the amateur radio HF digital modes. This article describes the accessibility of the PSK31 interface, which has features specifically for blind and vision-impaired hams:

          • Automatic text-to-speech.

          • Customized ham radio vocabulary.

          • Keyboard shortcuts, including access to the waterfall.

          • A PSK scanner that can speak the offset frequency.

          • High visibility text and colors.

   Incremental Speech and Voice Assist options augment the VoiceOver screen reader and Zoom magnifier utilities in Mac OS X.


CocoaModem is freeware developed by W7AY with an understanding of how ionospheric propagation affects digital mode signals. Before retiring from Apple, Inc, he was a member of a small and exclusive group of employees with the title "DEST" (Distinguished Engineer, Scientist, or Technologist).

   The cocoaModem 2.0 Web page reports that the program works with OS X versions 10.4 (Tiger) through 10.8 (Mountain Lion). In an email Mike, W5RST, pointed out that cocoaModem version 1.03  works well with OS X 10.9 (Mavericks).

   The program consists of a group of modems for working the most popular ham digital modes.  Each modem, eg the one for PSK, has a separate user interface and configuration panel.

   The online User Manual is easy to read, well-organized, thorough, and insightful.

User Interface

   The PSK interface (Figure 1) has three large text-view windows below the waterfall. The top two are for text received by each of the two PSK receivers, and the bottom window is for typing text for transmission.

Figure 1. The PSK interface.




   On a 13" screen the main cocoaModem windows are 5.9"H x 8.1"W. The label text is 0.07" high, so a larger screen and/or magnification with the OS X Zoom utility may be helpful.

   A wide range of Font/Style/Size options for text-view windows is available via the Font Menu. Access to high contrast color options is by single-clicking on color wells in the Configuration window in each modem.


   CocoaModem has an incremental (word-by-word) text-to-speech option that automatically speaks or spells a new word when it is received or transmitted. The modems with incremental speech are for PSK31, RTTY, MFSK, ASCII, and SITOR-B. The quality of Mac OS X speech is excellent, and W7AY has added an extensive list of substitutions that make spoken ham text messages easier to understand.

   CocoaModem text to speech is discussed in a separate article.

Voice Assist

   There is an optional QSO Info bar at the bottom of the PSK window (QSO menu > Show QSO Info). Keyboard shortcuts clear the Call Sign field or the Name field and position the cursor for you to start typing. Voice Assist speaks the characters as you type.

   Voice Assist also speaks the offset frequency when you use the PSK Table View to scan for signals as discussed next.

PSK Scanner

   In the Table View mode, the PSK interface simultaneously shows decoded text from up to 21 active stations. The Command-B keyboard shortcut opens the PSK Table View window (Figure 2). You can step from station to station in the table using the shortcut, Command-Period, which selects the next active station and tunes the PSK transmitter/receiver to that station on the waterfall. If Text-to-Speech is enabled, cocoaModem begins speaking the received text.

Figure 2. PSK Table View



Tuning and Filters

   If clicking on the waterfall to select an offset frequency is not an option, there are two different ways to tune cocoaModem. One method is to find a quiet spot on the band and call CQ. The Direct Frequency Access feature enables selection of an offset frequency using the keyboard instead of a mouse. Then you can tune using the VFO knob on the radio. This usually requires a narrow bandwidth filter in the receiver, eg, 100-250 Hz.

   The other tuning option is to use the PSK Table View scanner to find a station that is calling CQ. In that case the radio receiver filter should be wider, eg, 2400 Hz, so the PSK Table View can monitor a number of signals at once.

QSO Examples

   Two examples of PSK31 QSO's using cocoaModem demonstrate how easy these access features are to use.

For More Information

   • Accessibility section of the online User's Manual.

   • Article on "PSK31 Operating Notes from a Blind Ham."

   • cocoaModem Text-to-Speech.


   The cocoaModem PSK31 user interface has features designed specifically for blind and vision-impaired hams. They include automatic text-to-speech, keyboard shortcuts, a PSK scanner, and high-visibility font and color options.

   For blind and vision-impaired hams, cocoaModem is the HF digital mode program with the most features and the greatest ease of use.


   Thanks to W7AY and W1BLS for generous help and to W7AY for making cocoaModem accessible.

   Thanks also to Mike, W5RST, for reporting that cocoaModem 2.0 version 1.03 works with OS X 10.9 (Maveriks).

Author Information

   Peter DeNeef, AE7PD, is an Extra Class amateur radio operator in the U.S. This website has no ads or conflicts of interest.

Email:  HamRadioAndVision "at" gmail "dot" com.

rev. 2/16/2014

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