On Tue, Dec 06, 2016 at 10:00:40PM -0800, Denny Page wrote:
> Not sure what you meant here. The current code bases all its calculations of
> intervals base on the begin time of slot zero. Even if slot zero is bad, it’s
> total window is used in each time interval calculation. In the new code, a
> bad slot is never used in any way even if it is slot zero.
Yes, but that slot is just a reference to avoid loss of precision in
the calculation of the average. If its delay is large, it won't change
the result.
Let's say you have three samples (s_1, p_1, d_1), (s_2, p_2, d_2),
(s_3, p_3, d_3), and you want to calculate average of
o_i=(s_i + d_i/2 - p_i) using only the second and third sample.
The obvious way would be:
o = ((s_2 + d_2/2 - p_2) + (s_3 + d_3/2 - p_3)) / 2
But you can do it also like this
o = (s_1 + ((s_2 - s_1 + d_2/2) + (s_3 - s_1 + d_3/2)) / 2) -
(p_1 + ((p_2 - p_1) + (p_3 - p_1)) / 2)
This simplifies to the first formula. The first sample is included in
the calculation, but it doesn't change the offset. It's there just to
keep floating-point values small.
--
Miroslav Lichvar
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