How do I measure the minimum p-p cycle in a sine wave up to 6 KHz?

[marlon]

A shaft speed transducer (150 tooth wheel and magnetic pick-off) generates a sine wave. At various frequencies (up to 6 KHz), if the p-p amplitude of a cycle out of any 150 contiguous cycles (1 revolution) is less than a given voltage, the unit must be rejected.

[Jeremiah Cox]

Hello Marlon,
Since you are inputting data from a transducer into a computer, I will assume that you are using some Data Acquisition board and software to input this sine wave. Also, since you are posting in the LabWindows/CVI forum, I will assume that you are using LabWindows/CVI as your software environment. If you have the Full Development System (FDS) of LabWindows/CVI, it includes advanced analysis library functions. One of these functions is PeakDetector(). PeakDetector() will take an input array and return the peak locations and amplitudes. You could then use the MaxMin1D() analysis function on the amplitude array to determine the maximum and minimum values of your sine wave peaks. You could then compare the minimum value to your voltage threshold and re
ject the unit if necessary. If you do not have LabWindows/CVI FDS, then you will need to come up with your own functions that perform this analysis.

Jeremiah Cox
Applications Engineer
National Instruments
http://www.ni.com/ask

[marlon]

Thank you, Jeremiah! I appreciate the reply. Are there any DAQ boards you would recommend to do this? Also, I'm pretty sure I want to use the TestStand package to handle all of this (defining pass/fail criteria, managing different tests, printing test reports, etc.) Do I buy TestStand AND LabWindows/CVI???

[Jeremiah Cox]

Hello Marlon,
DAQ board specifications are not really my specialty. I would recommend calling your sales representative at 512-794-0100. They know all about the different DAQ boards and software packages and can help you to properly configure your order. I believe we offer TestStand and LabWindows/CVI both separately or together in the Developer Suite package. Keep in mind that you need the "Full Development System" (FDS) of CVI to use the easy Advanced Analysis functions I mentioned previously. You can reach me at http://www.ni.com/ask >> product Measurement Studio if you have any questions or difficulties.

Jeremiah Cox
Applications Engineer
National Instruments
http://www.ni.com/ask