Order analysis with counter input of tachometer (encoder)

[FFXX]

Hi!

I have an analog input task for my vibration data and an counter input task for my digital tachometer (Encoder Autonics E60H20). When I'm trying to perform order analysis in Playback window It's impossible to use RPM digital data as a speed profile. I've tried to use analog inputs for collecting data from encoder but the signal from it is very unstable (squares are not the same) and the standard speed profile detector doesn't work properly.

Can you help me to perform order analysis in this conditions properly? And how I should collect tachometer data for order analysis correctly?

I use for NIe 6363 for collecting vibration and tachometer data and SignalExpress 2012. 

 

Thanks. 

[KateB]

Please show how does the signal from encoder look like and post your SignalExpress script as well.

[FFXX]

I've added some pictures, project file and example file (see attached)

[FFXX]

How canI connect with NI specialists? 

[fromm8]

Hello FFXX,

Have you checked the "Getting started with the NI Sound and Vibration Assistant", there you can find a chapter talking about order analysis.

You can find it by going to start menu>>all programs>>National Instruments>>Sound and Vibration>>Assistant>>Sound and Vibration Assistant Getting Started Manual (Chapter 6). Starting from page 6-1 to 6-11.

Regards 

Frank R.

[FFXX]

Fromm8, thanks for answer, but I haven't found anything about my problem in this manual.

At this moment I understand that speed profile calculated in analog tachometer and signal which I acquired via counter measurement is the same thing. Am I right?

[fromm8]

Hello FFXX,

You should be more specific with "counter measurement" because we have different types of measurements with counters. However I think that the answer is no, they are not the same according to this document linked below on page 5:

Analyzing the Speed Profile

Regards

Frank R.

[FFXX]

Thanks, I get it. But I really do not understand what attributes should have a speed-time waveform to become a speed profile.

[fromm8]

Hello FFXX,

Look, on page 9 of the manual I linked above, you can find step by step how to configure the Order Spectrum (what you are doing according to the pictures). I know that manual is showing express VI's in labVIEW, but we have those functions as steps in the Sound and Vibration Assistant. If you see picture 6, we need to pass 2 inputs to the order spectrum step, one comes from your input signal, the second comes from "Analog Tacho Processing" step (from there comes the speed profile). In your picture I do not see any "Analog Tacho Processing" step for example.

For example, I acquired a signal, I saved it in a LVM file. Then I went to Playback, and there I used:

So in that example I am reading the input signal from the file(LVM), the analog tacho processing is using that signal, it is generating the speed profile as an output, finally the order spectrum is using the speed profile and the input signal.

Try to follow that guide, and apply those concepts from labVIEW to Sound and Vibration Assistant.

Regards

Frank R.

[FFXX]

Hello fromm8

 I do not use analog data for rpm measuring purposes because standard Analog Tacho Processing Express VI cannot process it properly (i have an encoder with 1024 pulse/rev. resolution and it has spiky analog signal). I have noticed that above. And there is no hardware problem. This is problem of processing. For example:

http://forums.ni.com/t5/LabVIEW/OAT-Tachometer-Incorrect-Results/td-p/373349

http://zone.ni.com/reference/en-XX/help/372416B-01/svtconcepts/tacho_sig/

thanks