ADC 212 and frequency measurement

 
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PostPosted: Thu Oct 16, 2003 9:54 am    Post subject: ADC 212 and frequency measurement Reply with quote
Hi,

I couldnt decide weaher this is a scope or software question appologies if Im wrong.

I want to use an ADC 212 to measure the output of two flow meters. The flowmeters output is a frequency proportional to flow (0Hz - 300Hz). Basically I want to measure the difference in flow between one and the other.

Is it possible to set the scope up to measure the difference in frequency between channel A and Channel B?

Can you apply scalling in the supplied software to convert the frequency to a flow value?

If not what is the easiest way to get the frequency from the scope using Delphi and the ADC 212 driver? I.e. is their a direct call to get frequency?

If not are their any recommended algorithms or methods to perform on the sampled data?

Luckily my system is fairly steady state so I can use a fairly long sample time (10 sec?) to help with the low frequency measurements.

Sorry its a bit long, thanks for your help.

John
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markspencer
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Joined: 07 May 2003
Posts: 610

PostPosted: Fri Oct 17, 2003 8:00 am    Post subject: Reply with quote
Hi,

Unfortunately, it is not possible to use the Software and apply mathematical functions to the Channels. However, a possible work around for you would be to save the .psd file and then save it again as a text file. The text file can then be imported into excel where you could manipulate the channel subtraction.

When collecting the data ensure that the callection is set upto chop. Setting | Channels. This means that there will only be on time interval between each reading. You might consider sampling at a faster time base to keep the time interval small.

Scaling can be applied to the amplitude in Picoscope (vertical) but not the frequency (horizontal) , this is done under Setting | Custom Ranges.

To use Delphi the simplest way would be to use our drivers and then apply an algorithm. I would suggest looking at some books to find out more information on this topic.

Best regards,
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