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Measuring phase angles on oscilloscope

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walters

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measuring phase angles

When measuring phase on the oscilloscope i see 2 waveforms one is leading or laging the other

example 1::

Waveform#1 is 10us laging Waveform#2

What is the phase angle of 10us?

how do i find the phase angle from a time measurement?


Example 2::

Waveform#1 is 40ms ("laging") waveform#2

What is the phase angle of 40ms?

How do i find the phase angle of 40ms?


Example 3::

Waveform#1 is 40ms "Leading" waveform#2

What is the phase angle of 40ms?

How do i find the phase angle of 40ms?
 

Re: measuring phase angles

Phase shift is φ = Δt * 360 / T degree or φ = Δt * 2 * pi / T radian,
where Δt - time delay (lagging), T - period of waveform
 

Re: measuring phase angles

Thanks for the formulas

can you please give me examples ?

on the oscilloscope all i can measure is the time distance between the 2 waveforms and thats in milliseconds or microseconds from each other so what do i do from there?
 

measuring phase angles

Hi;
for example: if one period is 40us and Waveform#1 is 10us laging Waveform#2 >
put this values in gevy formula yield:

φ = Δt * 360 / T = 10us * 360/ 40us = 90 deg

Regards
Davood Amerion
 

Re: measuring phase angles

Thanks for the information

if one period is 40us and Waveform#1 is 10us laging Waveform#2 >


Which waveform did u measure to get the period ? waveform#1 or waveform#2?


Another example:

if the period is 40us and waveform#1 is 10us "Leading" waveform#2

What is the phase angle for this one? it should be different
 

measuring phase angles

I have a question :
Is it possible measure phase diffrence of two difrent frequency !?
Answer is NO it is obvious that 2 wave form have same frequency.

Another example:
if the period is 40us and waveform#1 is 10us "Leading" waveform#2
What is the phase angle for this one? it should be different
we suppose wave form 1 has zero degree phase shift.
and measure phase diffrence for wave form2.

in the other word:
we can not specify phase angle of [just] one wave form, without any reference.
 

Re: measuring phase angles

Thanks

so how can u tell the difference of Leading and laging? which one is leading and which one is laging? how do i know if waveform#1 is leading or laging?

The leading phase angle how do i get this?
The laging phase angle how do i get this?

So the only way to measure phase is the waveform#1 and waveform#2 have to have the same frequency?
 

measuring phase angles

dear walters, phase diffrence just defined in 2 waveform which have same frequency.

In many cases leading and laging is not important,
but it is easer to get smaller one.
for example if waveform#1 respect to waveform#2 have 30 degree laging that means waveform #2 respect to #1 have (360-30) 330 degree phase diffrence (laging) or 30 degree leading.
I hope this description help you. :D

Regards
Davood Amerion
 

Re: measuring phase angles

Yes thanks for the help it does help me


But how do you convert Time measurements like

40us to degrees?
600ms to degrees?
100us to degrees?
20us to degrees?
70ms to degrees?
 

measuring phase angles

waveform periods of:
40 uS is 360 degree
600 mS is 360 degree
100 uS is 360 degree
20 uS is 360 degree
and
70 mS is 360 degree
One period (T) is 360 degree with any timming.
 

Re: measuring phase angles

Thanks for the help

Period=360degrees
frequency=period
Period= 800ms


40us Time delay Percentage of 360 degrees?
(40us is not the period its the time delay between the waveforms)
so if 800ms is the period what is 40us in percentage to 800ms?

600ms Time delay Percentage of 360 degrees?
(600ms is not the period its the time delay between the waveforms)
so if 800ms is the period what is 600ms in percentage to 800ms?

100us Time delay Percentage of 360 degrees?
(100us is not the period its the time delay between the waveforms)
so if 800ms is the period what is 100us in percentage to 800ms?

20us Time delay Percentage of 360 degrees?
(20us is not the period its the time delay between the waveforms)
so if 800ms is the period what is 20ms in percentage to 800ms?

70ms Time delay to Percentage of 360 degrees?
(70ms is not the period its the time delay between the waveforms)
so if 800ms is the period what is 70ms in percentage to 800ms?
 

measuring phase angles

answer of your 1st question:
40us= 0.04 ms
phase diffrence = ( 0.04ms/800ms ) * 360 degree = 0.018 degree phase diffrence
 

Re: measuring phase angles

thanks

So its 18 degrees of 360 degrees?
 

measuring phase angles

no ! 0.018 degree

Added after 1 minutes:

if phase diffrence is 40ms and period 800 ms then
(40/800)*360 = 18 degree
 

Re: measuring phase angles

Thanks for the help
I tried to calucalate the questions can u please corrent my answers please
im worried about the degrees and percentages

Period=360degrees
frequency=period
Period= 800ms


40us Time delay Percentage of 360 degrees? is it 18 degrees?
(40us is not the period its the time delay between the waveforms)
so if 800ms is the period what is 40us in percentage to 800ms? is it 5%


600ms Time delay Percentage of 360 degrees? is it 270 degrees?
(600ms is not the period its the time delay between the waveforms)
so if 800ms is the period what is 600ms in percentage to 800ms? is it 75%

100us Time delay Percentage of 360 degrees? is it 45 degrees?
(100us is not the period its the time delay between the waveforms)
so if 800ms is the period what is 100us in percentage to 800ms?

20us Time delay Percentage of 360 degrees? is it 9 degrees?
(20us is not the period its the time delay between the waveforms)
so if 800ms is the period what is 20ms in percentage to 800ms? is it .025%?

70ms Time delay to Percentage of 360 degrees? is it 31.5 degrees?
(70ms is not the period its the time delay between the waveforms)
so if 800ms is the period what is 70ms in percentage to 800ms? is it 12%?
 

Re: measuring phase angles

Period=360degrees
frequency=period
Period= 800ms

1 period = 360 degree
frequency = 1/T= 1/period

40us Time delay Percentage of 360 degrees? is it 18 degrees?
(40us is not the period its the time delay between the waveforms)
so if 800ms is the period what is 40us in percentage to 800ms? is it 5%

40us time lag in 800ms > 0.018 degree
what is the "5%" ???


600ms Time delay Percentage of 360 degrees? is it 270 degrees?
(600ms is not the period its the time delay between the waveforms)
so if 800ms is the period what is 600ms in percentage to 800ms? is it 75%

yes > (600/800)*360 = 270 degree
phase diffrence measure with degree not percent, [it is not used in phase diffrence]

100us Time delay Percentage of 360 degrees? is it 45 degrees?
(100us is not the period its the time delay between the waveforms)
so if 800ms is the period what is 100us in percentage to 800ms?

no! (0.1/800)*360=0.045 degree
because time dimension are diffrent first we must convert to one (same) unit eg. mili Sec.


20us Time delay Percentage of 360 degrees? is it 9 degrees?
(20us is not the period its the time delay between the waveforms)
so if 800ms is the period what is 20ms in percentage to 800ms? is it .025%?

(0.020/800)*360= 0.009 degree


and
70ms Time delay to Percentage of 360 degrees? is it 31.5 degrees?
(70ms is not the period its the time delay between the waveforms)
so if 800ms is the period what is 70ms in percentage to 800ms? is it 12%?

(70/800)*360= 31.5 degree
 

Re: measuring phase angles

Thanks alot for correcting my phase answers so i really know if im doing it right

Here is a percentage examples quote i just don't know the formula how to get the percentages of the total time period can you please help me out thanks

The period for 1kHz is 1mS. 50uS is 5% of the total time period, so the phase shift in degree's is 5% of 360deg = 18deg


Example(1)::

Period=1ms
Delay time= 50us

50us is 5% of the total time period

How did u get the 5%?
What formula did u use please?

example(2)::

Period=800ms
Delay time= 40us

40us is (?)what percentage of the total time period?

Example(3)::
Period=800ms
Delay time=600ms
600ms is (?)what percentage of the total time period?

Example(4)::
Period=800ms
Delay time= 100us
100us is (?)what percentage of the total time period?

Example(5)::
Period=800ms
Delay time= 20ms
20ms is (?)what percentage of the total time period?

Example(6)::
Period=800ms
Delay time=70ms
70ms is (?)what percentage of the total time period?
 

measuring phase angles

Phase shift is φ = Δt * 360 / T degree
φ = Δt * 2 * pi / T radian
where Δt - time delay (lagging)
T - period of waveform
 

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