Author Topic: Measuring sub 2Hz frequency with high accuracy  (Read 5423 times)

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Offline bdunham7

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Re: Measuring sub 2Hz frequency with high accuracy
« Reply #25 on: June 07, 2020, 07:04:32 pm »
Thank you bdunham7,

it does measure it if I put the entire waveform on the screen but as per my oy original post then the resolution is very low. I needed to measure it with a high precision (as high as possible, ideally 4 or more decimal digits).

OK, I thought you weren't even getting the two decimals.  The measurements in the menu are done with the on-screen information, so the precision is quite limited, I'm guessing you see something like 2.00 Hz, or even 2.0 Hz (which would be pretty crappy) and you want 2.0000.   It appears that neither of your instruments will give you what you want directly and you either have to use cursors, which will likely be no more precise, or some workaround like running your test signal into CH1 and your AWG into CH2 and then adjusting the AWG output to exactly overlap your test signal.  That should give you the precision you want.  That' s the best idea I've got.
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 
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Offline ricko_ukTopic starter

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Re: Measuring sub 2Hz frequency with high accuracy
« Reply #26 on: June 07, 2020, 07:36:00 pm »
Thank you bdunham7 :)
 

Offline ejeffrey

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Re: Measuring sub 2Hz frequency with high accuracy
« Reply #27 on: June 07, 2020, 10:01:09 pm »
Thank you bdunham7,
I just checked me Rigol MSO1104z and if the frequency is lower than 15Hz it just shows "< 15Hz". I assume because the internal counter overruns/rolls-over...

I would expect the counter in the signal generator would be better than that.  Have you tried to figure out why that was giving poor results?
 

Offline ricko_ukTopic starter

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Re: Measuring sub 2Hz frequency with high accuracy
« Reply #28 on: June 07, 2020, 10:14:43 pm »
The signal generator gives several decimal digits accuracy but had issues getting to trigger or give steady readins. The signal is very precise and stable but the readings were not. Now I managed to get the reading with enough accuracy.

Thank you all! :) :)
 

Offline bdunham7

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Re: Measuring sub 2Hz frequency with high accuracy
« Reply #29 on: June 07, 2020, 11:11:20 pm »
Thank you bdunham7,
I just checked me Rigol MSO1104z and if the frequency is lower than 15Hz it just shows "< 15Hz". I assume because the internal counter overruns/rolls-over...

I would expect the counter in the signal generator would be better than that.  Have you tried to figure out why that was giving poor results?

Add-on simple counters may lack features like noise reject and adjustable triggers that are necessary to get stable readings in some cases.  I was actually surprised shocked at how well the FY6900 handled it.
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Offline trobbins

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Re: Measuring sub 2Hz frequency with high accuracy
« Reply #30 on: June 08, 2020, 01:21:51 am »
So was it that you didn't initially configure the counter appropriately in the Rigol DG1032Z, or did you do some external signal modification, or ...?
 
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Offline ricko_ukTopic starter

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Re: Measuring sub 2Hz frequency with high accuracy
« Reply #31 on: June 08, 2020, 08:13:12 pm »
I initially tried every setting also with the scope connected to make extra sure the signals was always very clean. But wasn't working. Then I kept trying and suddenly it worked. No idea what happened.
 


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