I am planing to use my Arduino Mega as shutter control for my camera... its basically a square wave at 25Hz - 100Hz depending on frame-rate.
With a bit tweaking I can get my waves to be reasonable stable, at least thats what my oscilloscope says. Now I remember reading somewhere that you can't really use an oscilloscope to measure frequencies.. anybody experience with that?
According to the manual of my Agilent 1012A it has a 6 digit hardware frequency counter that goes from 5Hz to the scope bandwidth... so can I trust the scope, or do I need a separate frequency counter to measure my signal?
The datasheet for that 'scope specifies a timebase accuracy of 50ppm (0.005%). The same timebase generator will be used to perform frequency measurement : just how concerned are you?
mortos360:
Now I remember reading somewhere that you can't really use an oscilloscope to measure frequencies.. anybody experience with that?
I designed, sold, and supported digital Oscilloscopes for 12 years. I have never heard you can't use a scope to measure frequency. In fact, it is the #2 measurement people do with a scope. (I know, I ran a focus group to determine that.)
mortos360:
According to the manual of my Agilent 1012A it has a 6 digit hardware frequency counter that goes from 5Hz to the scope bandwidth...
The Agilent scope has a built-in frequency counter. So it is not measuring based on the waveform data but an actual hardware frequency counter is doing the frequency measurement, to make it more accurate.
Not only is a 'scope' a "poor mans" frequency counter, unlike a counter it will tell you at first glance whether you are "in the Ball Park" It's especially handy when building frequency multipliers...
jackrae:
The datasheet for that 'scope specifies a timebase accuracy of 50ppm (0.005%). The same timebase generator will be used to perform frequency measurement : just how concerned are you?
It isn't obvious, but timebase stability (in modern digital scopes) has little to do with the accuracy of time measurements...
When making measurements which rely on a threshold point on an edge, the measurement's accuracy is swamped by the noise of the vertical amplifier. As the sampled points of the edge move up and down due to noise, so do the calculated threshold points. Generally you aren't even able to see the timebase error because of the vertical noise.
Docedison:
Not only is a 'scope' a "poor mans" frequency counter, unlike a counter it will tell you at first glance whether you are "in the Ball Park" It's especially handy when building frequency multipliers...
Keep in mind, in this case, the OP is asking about a DSO1000 series from Agilent which uses a built-in frequency counter for the frequency measurement. It does not use the sampled waveform data.
