Thursday, March 29, 2018

Re: [Discuss-gnuradio] Dropping samples "D" when CPU at 60%

Hi Bakshi,
On Wed, 2018-03-28 at 21:37 +0000, Bakshi, Arjun wrote:

1--- The divider(blue) simply tells me when the signal(orange) power has increases more than X times w.r.t. older samples. It isn't exact, but good enough.


No, that's not really the whole picture: it much more tells you about when the older samples were *really* low. y/x grows arbitrarily fast for x->0, but only linearly for increasing y. I've tried to explain why this is a bad idea in my opinion.

2--- However, the divider output is unbounded, so I threshold it (green). 


notice that lack of boundedness is definitely a sign of lost information, and you throw away even more by thresholding.

3--- The threshold block's output holds at 1 until the input drops below a value, and doesn't give an impulse(green).


It gives a step. A step contains all frequencies. Especially, a step after your [1,-1] filter gives you an impulse.

4--- So I do the delay and subtract so that only transition points have non-zero values(red).


Exactly!

5--- Of which I want the 1st transition only, which is why I threshold again.


Why threshold? sounds like you want something that has a temporal behaviour, not a value amplitude-dependent behaviour

It isn't exact, but gets the job done. 


I think I've clearly laid out my feelings about that!

Best regards,
Marcus

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