Products > Test Equipment

Rigol HDO1000 and HDO4000 12bit oscilloscopes launched in China

<< < (168/258) > >>

Fungus:

--- Quote from: TomKatt on February 13, 2023, 07:33:52 pm ---I'm not nearly smart enough to fully understand all this, but I always thought sin(x)/x was some kind of 'approximation' that restored curvature to the sample data.

--- End quote ---

Yes, sin(x)/x reconstructs the original signal from the sample points.

sin(x)/x isn't an approximation, per. se., but for perfect results you need an infinitely wide filter and nobody can do that in practice.

It also only works if the original signal doesn't have any frequencies above the Nyquist rate, which is rarely the case in real life. Almost everything has high frequency harmonics.

TLDR; sin(x)/x wants to be perfect but real life won't let it.

richmit:

Some X-Y mode questions:

* I see in the manual you can pick a source for X & Y.  Can the source be a math result?
* Do cursors work in X-Y?
* Can you turn on color grade in X-Y?
* I see the "add a window" for X-Y.  So I can have a Y-T plot and a X-Y plot on the screen at the same time?
* Is the X-Y display impacted by the amount of memory used?  i.e. if you use more memory, do you get more points on the screen with a slower display update like the SDS2000X+?

switchabl:
Have you tried Hi-Res mode yet? In the new MXO4 video Dave shows that the Rigol has 14 bit @ 100 MHz and 16 bit @ 50 MHz settings. That latter seems way overoptimistic, 2 more bits correspond to roughly 12 dB improvement in SNR while 2x decimation should give only 3 dB.

Capturing maybe >10 Mpts of noise at the max. sampling rate with and without Hi-Res for offline spectrum analysis should tell most of the story. If you have a levelled 1-2 GHz signal source, checking the frequency response at different analog bandwidth and Hi-Res settings might also be interesting.

Martin72:
Hi,

I do not have a Ghz source here.

In the acquiremenu when you choose "Hi-Res", the bandwith will be displayed for 14 bit and 16 bit.
One channel only and full memory, 14 bit 200Mhz, 16 bit 100Mhz.
Drops down to 50Mhz and 25Mhz when all channel are active, drops further when you decrease the memory.
Pics of today:
FFT without source, 1mV/div, 50 Ohm, full bandwith, full Samplerate:Normal acquisition, Hi-res 14bit, Hi-res 16bit.
Last pic a 120Mhz sinewave with 1Vpp amplitude, Hi-res 16 bit active, amplitude decreased to under 700mVpp.

switchabl:
Interesting! So presumably the 200 MHz bandwidth limiting on the 4204 is done digitally using the same filter as the High-Res mode. That might also contribute to the differences in step response that you saw when you enabled 2/4 channels (as the filter will need to be different when the sample rate changes).

Also, it seems that "14 bit" mode is at least semi-plausible (in the sense that if you round up, there is a 2 bit-ish improvement over the nominal 12 bit without the filter) and is in line with other manufacturers' marketing claims. "16 bit" mode on the other hand is essentially "alternative facts" territory (14.5 bits if we are being generous).

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod