Lock-in Amplifier and DAQmx

[Ignacioz]

Hello I am having consistancy issues with the R output of this program. My reference is a square wave from chopper and the signal is from a detector after a medium. However; I am finding that every time I run the program I am getting some large variations on the output R. I was wondering what could be the source of this large variation (>25%).

The chopper signal is a 5v(pk-pk) square wave. The Detector is seeing a ~1.5v(pk-pk) square wave. the frequencies I am using is roughly 100hz.

thanks in advance.

[PhilipOrr]

I would like to build a lock-in amp using by PXI-6052e. Can anyone tell me before I start whether this PXI is suitable for this application?

Many thanks,

Philip

[cpt. fekal]

Hy

first of all thx a lot. That Amplifier works for me.

Do you happen to have a manual ore a how to for that amplifier. An instruction i-site of Ni would be fine, too.

For example I dont know how he seperates the signal from the ref. signal. Because there is just one physical channel. And what does he mean by Frequency, ore is that the ref. Signal????

Thanks a lot for your effort

greets Jan

[ArthurV]

Hello,

I have the same problem like Ignacioz. I am running a chopper setup, chopping at different frequencies. I have tried out different waveforms either. There seems to be an issue with squared reference. As far as I could determine, the PLL is not working properly when I am using squared waveforms. I am using the library from the NI Lock-In Amplifier Start-Up Kit. Is there any known solution? (Since the last post is old...)

Thanks in advance

Arthur

[Mitss]

Same problem here. If there is any solution let me know..

[B.Willing]

I'm new to Labview and the NI Lock-in amplifier, and I have a problem running the Lock-In (LabView 2013).

I'm using it with an USB-4431. I am simulating a squer wave reference signal within LabView and put it out via the AO of the USB-4431.

Via the front en BNC connectors, I send the AO signal to both AI0 (reference input) and AI1, just to test whether the Lock-in runs properly.

With a sampling rate of 102.4 kHz, things run properly as long as I chose a reference frequency of multiples of 100 Hz in the signal simulator (up to close to the Nyquist limit).

As soon as I chose a frequency which is not a multiple of 100 Hz (be it changing frm 4'000 Hz to 4'001 Hz), the frequency output of the PLL as well as the R value of the Lock-in start to fluctuate significantly.

Any idea what causes this behavious ?

Is there any way to find information on the settings of the Lock-in PLL ? I see an input named "parameters", but I can't find any information on this.

[B.Willing]

Correction to my above question:

1. I did find the contextual help - sorry for that.

2. The Lock-in works fine at multiples of 50 Hz (and of course 100 Hz). Lower multiples generate fuzzy behaviour.

[Alirezakh]

Hi

Can someone please tell me how to download the lock-in amplifier toolkit for the traditional Daq card?

I have been unable to find it on the website.

Thank you very much

Alireza

[agsb]

HI I don't know whether the threat is still active. Even I am working with lockin amplifier using labview. And I just started with it. The same problem as you mentioned here if I change the frequency of the reference and signal, I am unable to interpret the data. Could you suggest some ideas? 

I am giving 1V signal of frequency 1000Hz and the locked signal graph is not showing the 1V signal. Actually the signal amplitude is very less say 0.004V. Suggest how to work with it?