How do you convert a constant analog pulse to an incremental frequency?

[ProgChemist]

Hello,

I am a very new to the Labview format. I am a graduate student in chemistry trying to update an old Raman spectrometer (from the 70's) to a digital interface. 

I have measured two analog signals from the instrument.

One is a constant pulse signal of 100mV. This was used to drive a stepper motor on an old chart recorder. Each pulse corresponded to a single wavenumber----which, for every 5 pulses?-----would turn the chart recorder's knob one notch and allow the other signal to record the data for 5 wavenumbers.

The other signal ranges from 0 to 250mV. This is the signal of interest. It corresponds to the y-axis on the outputted spectra. 

What I am trying to figure out right now is how to convert these analog pulses into incremental wavenumbers which correlate, in real time, with the other 0 to 250mV signal.

Should I use an Analog software counter program,

And then go from there, with synching my other signal to it?

 Can anyone tell me if I'm on the right track?

[mrk1]

Hi,

Your application is quit interesting.

For the first question, Yes, You have to use the soft increment counter program which keeps on count up your incoming pulses of interest.

But I am not able to understand your second question. Could you please elaborate it.

MRK (CLAD)

[ProgChemist]

Yes,

First I want to be able to count the analog pulses and correlate them with a specific wavenumber (so I would start at a reference wavenumber, say, 200 wavenumbers---and then every pulse thereafter would correspond to 1 more wavenumber. So the first pulse would be wavenumber 201, the second 202, and so on). 

This would establish by x-axis for the desired spectra of a chemical sample.

My y-axis comes from a different analog signal altogether. This signal ranges from 0 to 250 mV--and the the magnitude of this signal received, at a specific wavenumber, corresponds to data about the chemical sample in question---at that specific wavenumber.

So, after I first establish my analog counter program, I need to correlate this program with one that detects my y-axis signal. So my y-axis intensity corresponds with the proper x-axis wavenumber.

Does this clarify my entire project enough?

[mrk1]

Yah,

From your explaination what I understood and got the solution, I am explaining below.

As you said the X axis value is being plotted for every fifth data point, what you can do is, you can acquire the X axis signal say for every fifth second, and whenever this 5th value reaches, you can acquire one point of Y axis signal. Repeat the same operation till your process of sample investigation ends. Now you will be having two array of values of X and Y. Now plot this in an XY graph. So your software plotted graph and the instrument plotted graph will be the same.

MRK (CLAD)