AC RMS difference of Real-time and psdata saved

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fcx6y
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AC RMS difference of Real-time and psdata saved

Post by fcx6y »

I am using PicoScope 6 with 4262.
As shown in the picture, the real-time AC RMS measurement result is 1.331mV, while the AC RMS of the same waveform saved as psdata is 3.514mV. I also save data as .csv and calculate with excel. The result is also 3.514mV, the same as the one saved as psdata. So is the real-time AC RMS measurement incorrect?
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psdata saved AC RMS
psdata saved AC RMS
Real-time AC RMS
Real-time AC RMS

bennog
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Re: AC RMS difference of Real-time and psdata saved

Post by bennog »

Taht is because the realtime RMS was calucated over the last 20 captures.
capture count colum.
The saved value shows 1
The realtime value shows 20.

Benno

fcx6y
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Re: AC RMS difference of Real-time and psdata saved

Post by fcx6y »

bennog wrote:Taht is because the realtime RMS was calucated over the last 20 captures.
capture count colum.
The saved value shows 1
The realtime value shows 20.

Benno
I use save all psdata, which contain 15 waveforms. The AC RMS of each waveform is the almost the same, which is about twice of the real-time AC rms. And the signal I give is constant, the real-time AC RMS also change only slightly over the time.
So can you explain why the real-time AC RMS value calculated over the last 20 captures is only about half the saved value?

Best Regards,
Yu-Meng

Martyn
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Re: AC RMS difference of Real-time and psdata saved

Post by Martyn »

Can you post the actual psdata files so we can take a look.
Martyn
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fcx6y
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Re: AC RMS difference of Real-time and psdata saved

Post by fcx6y »

Martyn wrote:Can you post the actual psdata files so we can take a look.
The psdata files are too big, The maximum allowed size is 512 KiB. Can you give me your email address? So i can send you the psdata files.
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saved
saved
realtime
realtime

Martyn
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Re: AC RMS difference of Real-time and psdata saved

Post by Martyn »

The email address is support@picotech.com if you just use Save Current Waveform it will help to keep the size down
Martyn
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fcx6y
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Re: AC RMS difference of Real-time and psdata saved

Post by fcx6y »

Martyn wrote:The email address is support@picotech.com if you just use Save Current Waveform it will help to keep the size down
I have sent the psdata files via email.
The size of the save current waveform is also 1061KB.
You can see from the save all waveforms file that the AC RMSs of all 15 waveforms are nearly the same.

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