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Note: This page describes MultiMode 3, which is for Classic (MacOS 8 and 9) Macintosh systems. If you are running OSX, you want to take a look at MultiMode OSX

MultiMode allows you to decode and transmit morse code, RTTY, FAX, SSTV, PACKET, ACARS, PSK31, ALE, and many other modes on your Macintosh, without any extra hardware. Just connect your Mac to your radio, and you're all set to go!

We're so sure that you've find MultiMode useful that we're offering you a risk-free deal. You can go ahead and download a copy of MultiMode for absolutely free. Give it a try, and see how easy it is to use. Once you've decided that you find it useful, go ahead and register your copy. If for some reason you decide MultiMode isn't for you, just throw away your copy. That's it!

What Is MultiMode?

MultiMode is an application which allows your Macintosh to decode several different modes of non-voice communication often heard on shortwave. You can also transmit in many of these modes, as well.

In the past, dedicated hardware, often costing hundreds or thousands of dollars, was necessary to demodulate and decode these transmissions. Today, you can use the processing power of your Macintosh to decode and display these modes, without any hardware.

MultiMode features sophisticated digital filters, for pulling weak signals out of the noise.

What Do I Need To Run MultiMode?

MultiMode requires a color Macintosh with sound input. A model with a fast (604 or G3 or G4) PowerPC (PPC) processor is highly recommended, although some modes can be decoded with any PPC processor. Since MultiMode is shareware, please feel free to download a copy, and see how it works on your system.

You also need a radio capable of tuning in the frequency ranges of interest. For most modes, this is a shortwave radio. For ACARS mode, a common VHF band scanner is used.

The audio from your radio (speaker or headphone jack) is fed into your Mac's sound input port, through an appropriate cable. The radio is tuned to the station, and the correct mode is selected. MultiMode has a feature which displays the audio spectrum of the station, as a tuning aid.


This is a screen shot of MultiMode decoding an SSTV picture on 14.230 MHz, received on March 6, 1999:
MultiMode 2 Screen Shot
(Click the thumbnail to see it full-sized.)

This is a screen shot of MultiMode decoding an RTTY transmission, received on March 6, 1999:
MultiMode 2 Screen Shot
(Click the thumbnail to see it full-sized.)

The latest version is 3.9.6, released on October 22, 2001. This version:
  • Bug fixed that could cause a crash in FAX mode
  • Improvements to FAX display grayscale
  • Ability to use AIRCRAFT.CSV aircraft database file in ACARS mode

MultiMode OSX is now available!

The cost of purchasing MultiMode is only $89!
(A lite version is also available, for $29)
Buy your copy online, and get your registration code in minutes!

Take a look at the list of modes supported in each version, along with a description of each mode.

MultiMode is currently only available for PowerPC Macintosh systems. No Windows version is available at this time.

A message board has been created for users of MultiMode. This is a forum to communicate with other users, and to exchange ideas and suggestions. Information about new and upcoming releases of MultiMode will be posted to the board.

Please consider taking our MultiMode Survey, the results will help us continue to improve MultiMode. This is your opportunity to let your voice be heard, and make suggestions as to what you like and dislike in MultiMode, and what new features you'd like to see.

Attention iBook Owners MultiMode has been tested and found to work with the Telex H-531 USB microphone, and the Griffin iMic, and should work with other USB microphones as well. You can read our USB Microphone tutorial for details.

Take a look at our MultiMode News!

Need help? Try our Useful MultiMode Links!

MultiMode supports the following languages:

  • English
  • Dutch
  • French
  • German
  • Italian
  • Spanish
Volunteers are welcome to help translate MultiMode into additional languages. Please contact

Awards and Ratings! gives MultiMode

VersionTracker gives MultiMode

Email your comments and questions to
Last modified July 29, 2003