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Graphing Frequency

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Graphing Frequency

Postby Autonerdz » Tue Sep 02, 2003 9:54 pm

Is there any way I can use PicoLog to graph frequency over time? I have been looking for a way to do this but no luck so far. Any suggestions? What paramaters can be graphed? I am using the ADC 212/3.
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Postby markspencer » Wed Sep 03, 2003 10:49 am

Hi,

To do Frequency by time graphs, select the channel and then select the frequency in the measurements dropdown box.

Settings | Input Channels | OK | ADD or Edit

In the window there is a scan time which determines the frequencies that can be read. This is described under the box and will change as the scan time is changed.

Select a data file that the data will be saved into and start a run the frequency will the be seen in the graph.

I have tested this with Picolog release 5.09.4.

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Postby Autonerdz » Thu Sep 04, 2003 5:28 am

Thanks, Mark.

I'm using 5.09.5

I realized I was in Fast Block mode and did not have that option of frequency. In real tine continuous I was able to do it fine. Sampling interval bust be 1 second or greater for it to calculate. It seems to be sampling maybe a couple of times a second but not sure. What is the max frequency it can calculate frequency? :wink:
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Postby markspencer » Thu Sep 04, 2003 8:19 am

Hi,

The Maximum frequency that it cam measure is approximately 650kHz.

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Postby Autonerdz » Thu Sep 04, 2003 4:25 pm

Thanks, Mark.

But lets say you were looking at a 900hz signal. What is the fastest rate it can sample and update? How many times per second is it recalculating that fequency? What are the best settings to optimize that speed?

I am interested in this for catching drop outs in optical crank sensor signals.

:shock:
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Postby markspencer » Fri Sep 05, 2003 9:15 am

Hi,

To calulate the minimum frequency that the unit will measure it is:

2*1/scan time

Where scan time has been turned into it seconds representation.

The maximum frequency is calculated in the following way:

((1/sample interval)/3)*2000)/scan time

where san time is in its second representation.

The rate of update is dependant on the scan time.

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