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Old Mar 12, 2010, 03:42 PM
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Silicon Valley, Calif
Joined Jan 2005
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Thank you for clarifying your design for high-resolution signal generation. As I read it, you intend to engage left and right output channels out of sequence to double your sampling rate. I encourage you to implement your solution and post an image of an oscilloscope screen with a 384kHz square wave on it. I wonder if you intend to use the same out-of-sequence technique on the input side.

You appear to believe that 22ms is the lower bound of lag when you generate a PPM pulse train. It is if you generate your packet in one go, buffer it, and then wait for it to play out the audio port. 22ms can be the upper bound if you generate your signal one pulse at a time. 400us of the high pulse is plenty of time to calculate how long the pulse for that channel needs to be and encode it.

I notice that you measure lag by estimating your feelings. This methodology seems to be working well for you and I encourage you to continue doing what's working for you. I note that one feature of this methodology is that it's hard for others to reproduce. Your feelings about the lag might even change between one measurement and another, making it hard for you to reproduce. I wonder if you can come up with a more portable measure of lag that you can put some numbers on.

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