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Strange handling of Audioinput in SmartSDR

DG6NFG
DG6NFG Member
edited April 2020 in SmartSDR for Windows
Hi together,
I recently experienced some strange behaviour of SmartSDR for Windows regarding the handling of audio input:
On my PC I use an external Audio-Interface offering two Microphone inputs - in Windows they are rendered as one Stereo channel.
I now have the following effect: When I use Channel 2 of the Interface (I would think represented as right channel in Win), I can see that theres is an audio signal in the signal meter in SmartSDR, but when enabling TX there is absolutely no modulation of the RF. Just using the other input works as expected.
I could agree that SmartSDR is using only one of the two channels by default, but then I would expect aswell not to see any audiosignal at all, and not just no modulation.

It this a bug of the SW, or a bug of the one sitting in front of the screen?

73 de
DG6NFG

Answers

  • Tim - W4TME
    Tim - W4TME Administrator, FlexRadio Employee admin
    edited April 2020
    It this a bug of the SW, or a bug of the one sitting in front of the screen?

    Neither. This is an issue with Windows and the audio hardware you are using.  The software we use to interface the Windows sound system to SmartSDR is PortAudio and we use the default recording device to capture the audio pin where the mic is connected. Most sound cards use only a single channel for the mic input. You are using a sound card that is not what would be considered "standard" with dual audio inputs and this is confusing PortAudio where is it not enumerating the sound devices correctly. 

    You will just have to use the other audio input as a workaround.
  • DG6NFG
    DG6NFG Member
    edited April 2020
    Well, thanks for the answer, but somehow it is still not really clear. How can the SmartSDR Audio-signal indicator show plausible levels (in P/CW window), if windows would not foreward audio to SmartSDR?
    This is basically the reason why it took me quite long to nail down the issue at all - if SmartSDR would have shown no incoming audiosignal at all, the reason why RF is not modulated would be obvious.
  • Tim - W4TME
    Tim - W4TME Administrator, FlexRadio Employee admin
    edited April 2020
    Because, as I indicated, the audio pin is not routing correctly.  The mic is not a stereo (2 channel) audio input so I suspect you are seeing both the left and right channels combined, but only the left channel is actually working. 
  • Al K0VM
    Al K0VM Retired Member ✭✭✭
    edited April 2020
    When using PC default Line input, It appears to me that both left and right channel audio are applied to the level meter and the transmit modulator. But only left channel audio is applied to the VOX function.  If I use MOX to key the radio both right and left channel audio will generate SSB RF. 

    AL, K0VM
  • DG6NFG
    DG6NFG Member
    edited April 2020
    Well, I was actually using MOX ...

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