Products > Test Equipment
Rigol HDO1000 and HDO4000 12bit oscilloscopes launched in China
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Veteran68:

--- Quote from: RobbiOne on December 07, 2023, 02:54:02 am ---I can't get any v2.12 FW for DHO1000 from international Rigol web site https://supportint.rigol.com.
Just the v2.11 (August 2023) from Rigol EU (Germany). Is it a special version available only for some country?

--- End quote ---

Did you look here, as was posted?

https://int.rigol.com/products/detail/DHO1000

I see it there.
David Hess:

--- Quote from: TurboTom on December 07, 2023, 01:58:43 am ---@thm_w: The jitter is rather aliasing due to frequency components at the edges of the input signal beyond Nyquist. This "misleads" the sinx/x waveform reconstruction engine and results in the visible jitter effect. You will find this effect on any digital scope without a proper filter in front of the sampling engine. It's probably the price we've got to pay for today's scopes where the "usable" frequency range approaches two thirds of the Nyquist frequency.
--- End quote ---

Exactly, but even with a perfect anti-aliasing filter, aliasing will still be present because of mixing products between the sample clock and input signal produced by non-linearity in the digitizer.  This can be shown by using a clean sine wave source which will still produce the "wobulation".  The non-linearity is present in the digitizer itself, but also results from jitter in the sample clock.

Older DSOs tend to be worse, especially those with interleaved ADCs because of greater non-linearity in the digitizer.  On these instruments the "wobulation" goes away when random equivalent sampling is used because the equivalent time sample rate is so much higher so there can be no aliasing.  Modern instruments which lack equivalent time sampling can use averaging (HP/Agilent/Keysight recommended this in an application note), but I do not think this is as effective.
2N3055:

--- Quote from: David Hess on December 07, 2023, 05:34:05 am ---
--- Quote from: TurboTom on December 07, 2023, 01:58:43 am ---@thm_w: The jitter is rather aliasing due to frequency components at the edges of the input signal beyond Nyquist. This "misleads" the sinx/x waveform reconstruction engine and results in the visible jitter effect. You will find this effect on any digital scope without a proper filter in front of the sampling engine. It's probably the price we've got to pay for today's scopes where the "usable" frequency range approaches two thirds of the Nyquist frequency.
--- End quote ---

Exactly, but even with a perfect anti-aliasing filter, aliasing will still be present because of mixing products between the sample clock and input signal produced by non-linearity in the digitizer.  This can be shown by using a clean sine wave source which will still produce the "wobulation".  The non-linearity is present in the digitizer itself, but also results from jitter in the sample clock.

Older DSOs tend to be worse, especially those with interleaved ADCs because of greater non-linearity in the digitizer.  On these instruments the "wobulation" goes away when random equivalent sampling is used because the equivalent time sample rate is so much higher so there can be no aliasing.  Modern instruments which lack equivalent time sampling can use averaging (HP/Agilent/Keysight recommended this in an application note), but I do not think this is as effective.

--- End quote ---
Siglent scopes have dot mode where they practically perform RIS (random interleaved sampling), although it is not marketed as such. If signal is triggering fast enough you get nice waveform reconstruction on repetitive waveforms, even when severely undersampled. So they don't market ETS or RIS but it still works as such.
core:

--- Quote from: egonotto on December 06, 2023, 11:49:54 pm ---
--- Quote from: core on December 06, 2023, 05:49:40 pm ---Indeed, noise level is very low.

1mV/div, 2 channels, 50 Ohm terminators on inputs, BW 20MHz / 200MHz, memory auto / max.
For me ch 1 have the highest bias, and ch 4 the lowest.


--- End quote ---

Hello,

Can you please make the measurements with 1 V/div instead of 1 mV/div?

Best regards
egonotto

--- End quote ---


Yes, see attached. BW 20MHZ / 200MHZ. 50 Ohm terminators.
About the same as TurboTom.
David Hess:

--- Quote from: 2N3055 on December 07, 2023, 06:26:30 am ---
--- Quote from: David Hess on December 07, 2023, 05:34:05 am ---...

Older DSOs tend to be worse, especially those with interleaved ADCs because of greater non-linearity in the digitizer.  On these instruments the "wobulation" goes away when random equivalent sampling is used because the equivalent time sample rate is so much higher so there can be no aliasing.  Modern instruments which lack equivalent time sampling can use averaging (HP/Agilent/Keysight recommended this in an application note), but I do not think this is as effective.
--- End quote ---

Siglent scopes have dot mode where they practically perform RIS (random interleaved sampling), although it is not marketed as such. If signal is triggering fast enough you get nice waveform reconstruction on repetitive waveforms, even when severely undersampled. So they don't market ETS or RIS but it still works as such.
--- End quote ---

That is effectively what HP/Agilent/Keysight recommended for DSOs which lack equivalent time sampling.  The problem is that even in dot mode, (sin x)/x reconstruction must still be used to determine the trigger point, so the aliasing moves the trigger point around corrupting the result.  Averaging helps, but it does not produce as accurate a result as equivalent time sampling.

As a practical matter, the difference should be irrelevant.  In both cases the bandwidth of the instrument is insufficient to accurately represent the signal.
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