Tone Measurement VI, How does it work?

[laserjet4200]

Hello,

I've built a VI as part of my PhD for measuring the phase of the power system 50Hz waveform.  The core of the VI is the Tone Measurement block.  I have tested the system using a commercial product and the Tone Measurement block seems to function correctly, however I keep getting asked to describe the exact process by which the block determines Frequency and Phase.

I know from looking into the sub-VIs that it ulimately uses an FFT block, but was wondering if anyone can throw some light on the exact FFT method being used?

Thanks in advance

[Robert_Lee_NIUK]

Hi,

I've had a look at the VI and you're right, at the lowest level is an FFT function. This particular FFT is a Real FFT because you are inputting Real data. The library call is then just a standard FFT algorithm. There's a couple of really good Knowledg Base and Tutorial articles on the differences and methods used by the FFT functions and I've linked them below.

http://digital.ni.com/public.nsf/allkb/F70DB3441DC5AB9986256E97005BA825

http://zone.ni.com/devzone/cda/tut/p/id/4278

http://zone.ni.com/devzone/cda/tut/p/id/3772

http://zone.ni.com/devzone/cda/tut/p/id/4844

I hope this helps.

Best wishes