DAX Flowchart

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  • Updated 3 years ago
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Does anyone have flowchart that explains the inner workings of DAX. I'm trying to explain it at our radio club meeting.
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Bob G W1GLV

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Posted 3 years ago

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Walt - KZ1F

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Bob, where nobody has responded to you let me try to answer. In that way either others can say, "what he said" or tell me, and the world, why I was incorrect.

So, there are three components to DAX, SSDR the client program, SmartDAX or DAX the applet started upon Windows boot, and the consumer, be it fldigi, DM-780, or whatever.

SmartSDR merely associates a given slice, A->H or A->D, with a dax channel. That, it appears is the extent of it. Upon a restart of SSDR the radio knows the linkage between the DAX channel and the slice so in the status messages that flow from the radio, it lists that association.

SmartDAX or DAX actually controls the DAX audio stream. SSDR doesn't turn that on, merely establishes the linkage slice to dax channel. So by depressing DAX channel depicted on the DAX applet it requests that DAX audio be started on that channel. In so doing, it registers a callback of the data flowing so 1) it can reflect the signal strength and adjust if 50% is too high or low and it pushes the data into the corresponding fake audio port created by, I am guessing, installation of SSDR.

So now data is received by the DAX applet and it writes that data into the audio port which the end consumer app listens to.

Now, there is also a transmitted stream that the consumer app produces. When it writes into the transmit (or microphone) port the DAX applet consumes it and feeds it back to the radio on the UDP port assigned to that DAX channel.

So the DAX applet is the intermediary between the the consumer app, DM-780 or Fldigi and the radio, where SSDR merely makes the relationship between the DAX channel and the slice.
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Walt - KZ1F

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It's verbal as 1) I don't have PowerPoint and 2 I don't do presentations on the FRS environment.
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Steve - N5AC, VP Engineering / CTO

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Official Response
Here's the basic picture when you are using a Windows PC and using virtual sound cards:



And here's what happens:
1. SmartSDR for Windows communicates to the radio what DAX channels you want for any/each receiver through API commands and does all other radio control functions (create receivers, tune them, etc.)
2. The DAX control panel (optional) turns on or off the DAX channels and makes adjustments to the audio levels for the streaming VITA-49 data that also travels along this path (2).
3. The DAX control panel exchanges samples with virtual sound card drivers installed with SmartSDR that make the DAX system look like sound cards in your PC
4. Your digital mode program connects to the sound card to transmit and receive data.

Note that this picture just shows audio samples and does not show control information for the radio (frequency, transmit, etc) which is done over CAT.  DAX can also completely eliminate the DAX Control Panel and the DAX Virtual Sound Card Kernel Driver if the Digital Mode Program (yellow box) can talk directly to DAX using UDP/TCP/IP.
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km9r.mike

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Steve some follow ups if that is ok ? DAX virtual sound card software resides in the flex SS rig (?) and just the control panel software resides in the pc or are both installed in the pc ? Also what is the current development level of the dax virtual sound card ? I think it's performance is fantastic and it's operation is worry free but was curious if even better things wrt performance  are on the horizon. Thanks
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Steve - N5AC, VP Engineering / CTO

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Steve some follow ups if that is ok ? DAX virtual sound card software resides in the flex SS rig (?) and just the control panel software resides in the pc or are both installed in the pc ?

Look back at the picture -- the blue boxes are the hardware and show you where things execute (run).

Also what is the current development level of the dax virtual sound card ? I think it's performance is fantastic and it's operation is worry free but was curious if even better things wrt performance  are on the horizon. Thanks

Not sure I understand the question -- are you asking if we're planning on performance improvements for virtual sound cards?  If so, I'm not aware of any performance issues.
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km9r.mike

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That is what I assumed from the diagram but did not want to assume. Thanks

I too did not say that there were performance issues but was just wondering if there were even higher performance possibilities in the works but I guess not. Thanks as well.