WSJT-X Multiple instances on Raspberry Pi 2 - USB sound cards

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G3ZIL
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WSJT-X Multiple instances on Raspberry Pi 2 - USB sound cards

Thought I'd log here my experience of running two instances of wsjt-x on a Raspberry Pi 2.

The only problem concerned USB and the two sound cards (Daffodil C-Media).
I had both cards plugged into a (generic brand) 4-port USB hub.

Running the second instance of wsjt-x, or, as a test, the linux arecord command, clobbered the audio in the first wsjt-x instance with much distortion and "popping" on the second audio stream as well. Further testing with arecord, even at 4000Hz sampling rate, showed the same behaviour.

The simple solution was to have one sound card on the hub and one directly into a USB port on the Pi.
This worked immediately, with no interaction. Various on-line posts seem to point the finger at the limitations of a single "transaction translator" within the hub.

73
Gwyn
G3ZIL