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@Registered Member posted:

I guess the members here would be able to help better if you can give more details. For example, describe the waveform and explain the purpose for the conversion. There are possible ready answers to your specific case.

Regards- Ali M. Al-Shurafa

I want to see the angle/ phase associated with sine wave of particular frequency tracked with Tachometer.

I am really not sure if that's a correctly way to do?

@Registered Member posted:

I want to see the angle/ phase associated with sine wave of particular frequency tracked with Tachometer.

I am really not sure if that's a correctly way to do?

Google β€œwavelet” and you’ll learn the details of the signal processing technique.

But if you are just seeking angle and phase associated with a sine wave it might be helpful to know what hardware you are using.  Without going into specifics, typically the phase lag angle is the angle represented by the time as measured from the reference once-per-turn marker to the next positive peak.

Based on your recent post, I'm not sure you would really need wavelets or other advanced functions. I'll assume your case is at a plant or a shop where you have a machine and tools to measure the vibration and phase.

The vibration device gives you the waveform signal. The key phasor device gives you the reference signal (usually) from the shaft. When both signals are combines, the phase angle is the difference between the phase puls and the next positive peak on the waveform.

Based on the system you have, the phase angle value can be manually estimated or automatically calculated. WRT the mathematics, if you have the waveform as digital (discrete tabulated values), you may use the maximum positive value at a target Tp. The time for the puls is T0. The phase is DeltaT = Tp-T0.

When phase is calculated, typically the calculation is for a specific frequency (filtered waveform). See the image below (Right: without key phasor dots, Left: with key phasor dots).

Regards- Ali M. Al-Shurafa

Waveform with without phasor Shurafa

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  • Waveform with without phasor Shurafa

I want to see the angle/ phase associated with sine wave of particular frequency tracked with Tachometer.

It is not clear what is meant by a tachometer.  I assume this measures shaft rotational speed. 

If you had a sinusoidal shaft reference, like you might in power generation, then you could get 'phase' relative to this signal 1) via a transfer function on a two channel analyzer 2) a. multiply the ref. tach signal times the 'vibration' and filter to d.c. (low pass) b. find a derivative of the ref. (in power this could be available) multiply signal by this, too. Filter to d.c.  c. these two values give a direct and quad, which can be converted to phase. 

The TF method is simpler depending upon the software you have.  When looking for phase vs. a reference, make sure it is coherent.  Also, if your reference is not a sinusoidal signal, the TF method produces a mathematical relationship.  For things like pulses (and really any ref. signal) if the signal varies, the phase can vary also.

If your tach. reference signal is a shaft reference, standard devices work.  Also, the reference multiply will work if you generate a cosine and sine signal that starts at the shaft reference - this is the way that Bently Nevada used to do it; this dates back decades at least to the 1920's or 1930's.

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