Virtual Audio Cables

With the Flex-3000 in house, I wanted to set up to use some digital modes. The instructions led me to the Virtual Audio Cable (VAC) program to make the digital audio connections between the digital mode software (e.g. DigiPan, JT65) and the PowerSDR program that runs the Flex.  The basic features of VAC are described in the program's help file and are illustrated in the following figure from that source.

 VAC provides a one-way "pipe" to interconnect digital audio streams between programs on a single Windows PC. The figure shows multiple applications that play or generate audio, connected to a single virtual cable that can then connect to multiple applications that accept audio input. To test the ability to combine multiple sources, I set up the arrangement shown below. In the VLC media player and the PowerSDR program I selected the same virtual cable for their outputs. At the Skype program I selected the virtual cable for its input. In a test call using Skype, the audio streams of both sources were audible. The audio level for each source must be set in its respective program.  

The ability to combine multiple audio streams and to transport the result to multiple programs may provide some possibilities for implementing audio patches for remote callers to access a radio transceiver.  Using two virtual cables I connected the Flex-3000 to Skype or to a Google Hangout for bidirectional audio and made some test calls to verify transmission. Below is a figure showing the test arrangement.

This arrangement provides sufficient audio paths for a single remote operator to talk through and listen to the transceiver.  

As usual, the challenge with a third-party patch is to find a place where the local station microphone can connect to the transmit audio and to the distant caller. Possibilities include:

• Station microphone connected to the transceiver in the normal manner, working in harmony with the audio on VAC1 (if they are not mutually exclusive)
• Microphone connected via some audio program to the VAC1 for transmit
• Microphone connected via some audio program to the VAC2 for talking to the remote device user

Transmit audio monitoring, built into the transceiver, enables the station operator to hear the audio transmitted by the distant caller.

In the absence of audio stream bridging within the Windows PC, a second Skype or Google Hangout session can be connected via conference call with the session that provides the transceiver patch.

Further testing is needed to determine what programs and devices are  available to implement the full patching capabilities.