Programming PLL to lock on low frequencies (~200Hz)

[shaniro]

Dear Madam/Sir,

I have an experimental setup of a plate rotating at ~200Hz. I read a short pulse per each revolution of the plate (light sensor &slit).  

I'm trying to lock on the frequency and phase using PLL  but I've encountered two main difficulties:

1. It seems that the PLL.vi is able to lock only on sinusoidal or rectangular pulses signals. Is there another vi i should use or there is a way to overcome this problem in the PLL.vi (my signal is more or less a delta function per revolution)? 

2. I find it difficult to lock on frequencies lower then ~300Hz even when I use a chopper that creates a nice rectangular signal and playing with the lock parameters (TC duration, LPF info, etc.). Is there anything I could do in order to improve the PLL's performance at low frequencies?

Thanks,

Shani Rosen

The Hebrew University of Jerusalem
The School of Engineering and Computer Science
The Department of  Applied Physics
Tel: +972 2 658 6401
Email: shaniro26@gmail.com

[Aaron O]

Where is this PLL.vi coming from? Could you provide more information about your current application and how you are implementing a phase lock loop?

[Tom__Sedlack]

1 pulse per revolution seems too little.  Try adding more evenly spaced slots to your wheel then compensate for pulses per revolution in the vi.  The more slots, the better the resolution.  

[RaymondTan]

I have similar problem. I am using HEF4046B to lock AC signal and a fan rotating at 60Hz. How do you solve your problem?

[bahannah]

Hey RaymondTan,

To get more visibility on our forums, I would suggest creating a new forum post and referencing this one. In general, we recommend not commenting on very old posts as they have very low visibility.

Regards,

Hannah L.

Applications Engineering 

National Instruments 

www.ni.com/support