Test and Measurement Forum

Math channels

Forum for discussing PicoScope version 6 (non-automotive version)

Math channels

Postby Gwill50 » Mon Oct 06, 2014 10:56 am

Does anyone have a formula for rpm?
I am not good at math but would like to have a quick way of determining engine rpm using both ignition events
as well as crank and cam sensors. I tried 60000/freq(a) but gave no joy. I can't seem to find any usable information
for beginners such as myself, and a push in the right direction would be greatly appreciated.
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Re: Math channels

Postby Martyn » Tue Oct 07, 2014 10:45 am

I would suggest you pop across to our Automotive Forum where you will find discussions on this topic

For example http://www.picoauto.com/support/post32131.html
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Math channels

Postby wgoettler » Mon Nov 24, 2014 11:00 am

I am searching for a "math channel" formula to display time diff between rising high A and B.
A is a pulse for an ultrasonic sensor, B is the echo of the sensor.
The time diff between rising A and rising B is the time (way) of the signal.
Now I want to have a curve which represents the passed mm.
Example:

Assumption Signaltime 34,346 cm per 1 ms at 20°C.
Measured Timediff 5,584 ms

34,346 * (5,854/2) = 100,530 cm

See attachment (measured 2,123 ms which is 36,458 cm)

I would be happy if there is a way to display the distance directly in PicoScope!

Regards,
Wolfgang
Attachments
PicoScopeScreenshot.jpg
UltraSonic
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Re: Math channels

Postby Martyn » Wed Nov 26, 2014 10:13 am

I am not sure it would be possible to take this measurement, however if you can post a psdata file for the waveform you have shown in the image then we can take a look.
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Re: Math channels

Postby wgoettler » Wed Nov 26, 2014 7:58 pm

Hi,
maybe this one helps...
On "scope view 4" I'm using already the "Rise Time Measurement" which is in general not too bad.
Display the masurement result now on a scope view could be the solution.
Multiple echos could be a problem with this measurement, because only the first echo is relevant for measuring distance. Looking forward for your ideas...
THX for your support
Wolfgang
Attachments
20141126-0002.psdata
Ultrasonic Echo
(221.44 KiB) Downloaded 46 times
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Re: Math channels

Postby Martyn » Wed Dec 10, 2014 7:50 am

You can get a similar result by using a maths channel, (3*A - B) in this example and then using High Pulse Width measurement (Cycle at Ruler 1) and just drag the ruler across the screen to near the ones you wish to measure.

The time between edges on two channels is already on our feature request list, although there are no indications as to if, or when, this will be implemented.
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Re: Math channels

Postby wgoettler » Wed Dec 10, 2014 3:58 pm

Not sure if I understood / did it correctly...
But "High Pulse Width" is not displaying a value.
Time measurement between edges in math channels would be great :-)
THX for your support
Attachments
20141210-0001.psdata
US pulse width
(223.97 KiB) Downloaded 38 times
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Re: Math channels

Postby Martyn » Mon Dec 15, 2014 1:49 pm

The cursors you have pulled in for View 4 are the phase cursors (green circles), you need to pull in the time cursor (white square) from the bottom left and then the values will display.

I will continue to push for time edge measurements so keep checking back.
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