How mush is the phase-shift between this two waves?

[arvinfx]

Hi, How can I calculate exact phase-shift between this two waves:


Main frequency is 50Hz.

 

[simonbramble]

at a guess 234 degrees. Looking at the peak of the yellow waveform and the peak of the blue waveform, on a timebase of 2ms per division, they are 13ms apart.

50Hz has a period of 20ms, so 13/20 x 360 = 234 degrees.

This looks about right since the peak of the blue is just past the trough of the yellow (the 180 degree point), but just before the 3rd quarter (which is 270 degrees)

 

[simonbramble]

it might help if you bandwidth limit the traces

 

[JimB]

I have a different interpretation.

Consider the peaks of the 50Hz waveforms at the left hand side of the display, they are 3.5 divisions apart, ie 7mS

Calculating the phase difference 7/20 x 360 = 126 degrees.

JimB

 

[ChrisP58]

I expect that your scope has a phase measurement function.

I don't know what model your scope is, but page 4 of this document shows how to enable it for a DS1104Z
https://beyondmeasure.rigoltech.com.../EDU Advanced Lab Guide.pdf?sid=TV2:3QisWJtQW

That said, you might have enough noise in the signals that the internal measurement might get confused. Limiting the bandwidth can reduce the noise. (As simonbramble said)

 

[arvinfx]

Thanks guys

I calculate 125 and /or 360-125=235 depends on with wave is ahead of other.
My oscilloscope is confused because of noise on the main wave .

Now how can I synchronize this two waves?

This is two amplifiers and i have to do it with pre-amp or something like that.

Regards

 

[simonbramble]

Both Jim and I are right. It depends on which waveform is leading which. If you add my 234 degrees to Jim's 126 degrees, you get 360 degrees

 

[JimB]

If you add my 234 degrees to Jim's 126 degrees, you get 360 degrees

Agreed.
But the basic waveform is a repetitive sinewave and with no knowledge of their origins in a system it is impossible to say which one is leading/lagging by 126/234 degrees.

So, keep it simple and show the phase difference as something less than 180 degrees.

JimB

 

[arvinfx]

Thanks guys

Now how can I synchronize this two waves?

This is two amplifiers and i have to do it with pre-amp or something like that.

Regards

Gentleman ?

 

[Nigel Goodwin]

Gentleman ?

You need to give FAR more information, your questions make no sense without context.

 

[BartDP]

There is no simple solution to shift a signal over a given degree quantity ...
Especially not at 50 Hz.
Can you explain where the 2 signals are coming from, and why they need to be in phase ?

 

[Buk]

There is no simple solution to shift a signal over a given degree quantity ...

Hm. Shouldn't he be able to shift one of the signals on screen using this control;

Or did I miss his point?

 

[BartDP]

Arvinfx is talking about 'two amplifiers' , even 2 different amplifiers I thinks, as I suppose he is giving each the same input.
If this is the case, easiest solution is to replace one to have 2 the same.

 

[arvinfx]

Right,
There is an audio waveform comes from a TV (Vpp is 230mv) and goes to two separate stereo amplifiers.
As I mentioned and you kindly help me to find the phase-shift is 126 degree "IN SPEAKER OUT" compare to each other.

The issue is to make this two in same phase. So I think I need a phase-shifter circuit for at least one of them it means , one amplifier will directly connect from TV and other one will give the signal from the "phase-shifter circuit" and with a potentiometer I would make them is same phase.

The reason of this is:
I had 4 channel amplifier before and I don't have it now ( have to replaced with 2 amps) before that I feel the bass of musics really sync , clear and amazing ( I can not tell it by words) but with new system I feel bass has cut or weak or distortion and it is not good at all.

Regards

 

[BartDP]

As said, no easy solution ( or cheaper solution then buying 2 identical amplifiers) for this ...

 

[crutschow]

So I think I need a phase-shifter circuit

For simple phase-shift circuits, the phase will vary with frequency.
Over what frequency do you need to shift the phase and how much does the amplifier phase-shift change over that range?

 

[Nigel Goodwin]

Right,
There is an audio waveform comes from a TV (Vpp is 230mv) and goes to two separate stereo amplifiers.
As I mentioned and you kindly help me to find the phase-shift is 126 degree "IN SPEAKER OUT" compare to each other.

The issue is to make this two in same phase. So I think I need a phase-shifter circuit for at least one of them it means , one amplifier will directly connect from TV and other one will give the signal from the "phase-shifter circuit" and with a potentiometer I would make them is same phase.

The reason of this is:
I had 4 channel amplifier before and I don't have it now ( have to replaced with 2 amps) before that I feel the bass of musics really sync , clear and amazing ( I can not tell it by words) but with new system I feel bass has cut or weak or distortion and it is not good at all.

Regards

Bit more information now, but still very lacking - such as the makes and models of the amplifiers - your 'problem' is very strange, and not something that usually occurs or is ever a problem. I'm pretty bemused by even putting a scope on the outputs.

Is one of the amplifiers a class-D one perhaps?.

 

[danadak]

Phase shift due to different crossover networks in speakers ? Some speakers in
back have switch adjustments for cutoff which affect phase at speaker. They also
would affect amplifier loading and possible phase shift.

If you need to build a phase shifter network allpass would be the ticket -

Allpass Network Shifts 90 Degrees over Wi | Maxim Integrated

Two wideband transconductance amplifiers produce an allpass network. Combining two such networks as shown in the illustration produces two outputs with a constant 90 degree phase shift (vs. frequency) between them.

www.maximintegrated.com

https://pdfserv.maximintegrated.com/en/an/AN184.pdf

In your scope, "Acquire" button, "Mode" then set it to "Average", adjust "Averages" setting to 64 for starters.
That will get rid of noise.


Regards, Dana.

 

[unclejed613]

Is one of the amplifiers a class-D one perhaps?.

and if it's class D, is it using DSP? the shown phase shift could be the processing delay of a DSP chip.

 

[arvinfx]

For simple phase-shift circuits, the phase will vary with frequency.
Over what frequency do you need to shift the phase and how much does the amplifier phase-shift change over that range?

Yes I made two kind of all-pass filter circuit and test it both from 20-20khz , phase shift is depends on frequency!
One amp has 180 phase shift on all frequencies , Another one I have not checked yet.