Hi, not sure if this should be PIC or EE, but I have opted for  PIC
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I have an application where I need to measure the phase difference between =
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two sine waves of same frequency. I'm using two zero crossing detectors to =
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trigger the CCP1 and CCP2 inputs of a PIC. The CCP counter is  clocked by a=
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PLL/VCO at 360 x the sine wave frequency, so the  difference between the=20
CCP1 and CCP2 counts provides a direct phase measurement  with a resolution=
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1 degree.
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So far so good, however the sine waves have some jitter so I thought I =20
would take the average of a few consecutive phase measurements. That is  wh=
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I come unstuck, how do you average phase readings?
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To illustrate the problem, if the phase is jittering about zero  degrees=20
giving 4 phase readings of say, 358, 359, 1 and  2 degrees, a simple averag=
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calculation yields 180 deg, which is  obviously wrong. Does anyone know how=
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calculate the true average,  which  should be 0 degrees? I'm sure the answe=
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is obvious, but it has defeated me so  far.=20
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 Richard Golding
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