Be aware that peak detect is only effective if the ADC (and peak detector) is running fast enough. The same is true for high-res and random sampling. On the 924 this would not be the case anymore with 4 channels enabled. A switchable (analog) low-pass filter would certainly help, as would ETS (for periodic signals). I do not know if either is available on the Rigol.
Be aware that peak detect is only effective if the ADC (and peak detector) is running fast enough.
Be aware that peak detect is only effective if the ADC (and peak detector) is running fast enough. The same is true for high-res and random sampling. On the 924 this would not be the case anymore with 4 channels enabled. A switchable (analog) low-pass filter would certainly help, as would ETS (for periodic signals). I do not know if either is available on the Rigol.
btw, i tried touch pen that came with my EraSynth and NanoVNA, both cannot work on DHO800's screen too bad.. (pen.jpg) fwiw...
btw, i tried touch pen that came with my EraSynth and NanoVNA, both cannot work on DHO800's screen too bad.. (pen.jpg) fwiw...
There's pens for resistive screens and pens for capacitive screens. You have to get the right type.
Using a mouse is more effective but wait, for this need you only have 1 USB A port and it seems from reports a USB hub will freeze the scope.
Be aware that peak detect is only effective if the ADC (and peak detector) is running fast enough.On Keysight peak detection mode will actually decrease sampling rate at certain timebases.
Peak detector mode is anyways a crutch, you cannot use FFT and measurements with it.
It destroys signal details, it is useful only to show signal envelope on screen.
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I think people are confusing the several "sample rates" within a scope. The ADC sampling rate and acquisition sampling rate (which is the data stored to memory) are not always equal. And what happens between those steps is not consistent between difference scopes/brands.
The megazoom "issue" that you've pointed to (out of context) is those scopes reducing the acquisition sample rate when in non-8bit modes, (peak detect, averaging, high resolution) as the acquisition rate changes to fill the available aquitision memory (keeping the horizontal timebase the same). The ADCs keep running at their full rate for all acquisition modes, just as the Rigol do, tuning on more channels increases the multiplex to the ADCs and drops the per channel ADC sample rate (XXGS/s to 0.5*XXGS/s).
switchabl is correct that the ADC sample rate is determining the peak detect capture window (unless some scopes have analog domain peak detect?).
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I think people are confusing the several "sample rates" within a scope. The ADC sampling rate and acquisition sampling rate (which is the data stored to memory) are not always equal. And what happens between those steps is not consistent between difference scopes/brands.
The megazoom "issue" that you've pointed to (out of context) is those scopes reducing the acquisition sample rate when in non-8bit modes, (peak detect, averaging, high resolution) as the acquisition rate changes to fill the available aquitision memory (keeping the horizontal timebase the same). The ADCs keep running at their full rate for all acquisition modes, just as the Rigol do, tuning on more channels increases the multiplex to the ADCs and drops the per channel ADC sample rate (XXGS/s to 0.5*XXGS/s).
switchabl is correct that the ADC sample rate is determining the peak detect capture window (unless some scopes have analog domain peak detect?).
With "normal" sampling configuration, the DHO900 is actually boxcar averaging when the "Shadow Memory Sampling Rate" is lower than the ADC rate which apparently stays the same all the time (only activating additional channels multiplexes this sample rate over the enabled channels). See here: https://www.eevblog.com/forum/testgear/rigol-dho804-test-and-compare-thread/msg5109618/#msg5109618
Well, it can show RF signal on VHS VCR - its nice! But now I've stumbled on - why 2nd head isn't showing and not reacting to adjust of tape path - maybe its dead? Can I hook it up to video head directly - or output level will be to low for dho804?
Can I hook it up to video head directly - or output level will be to low for dho804?
...the gaps between them are longer than I would expect.
how do you know its boxcar averaging?
how do you know its boxcar averaging?
This is quite easy: When doing a single shot trace of preset sample count and analyze the individual samples, you can easily see the quntization of the values (like the "bins" in a histogram). At 1.25MSa/s, 1V/div you will find a quantization of approx. 2.31mv, which, assuming a quantization of 12bits (as per Rigol's specs), results in a total peak-to-peak range of approx. 9.5V which easily matches the 8 vertical divisions (8V) of visible vertical range.
The same test with a sampling rate of 100kSa/s has a quantization of approx. 0.2875mV which leads to a resolution in the ballpark of 15 bits. Since in a single shot, the calculation of a classic "isotemporal" average isn't possible, and the sampling engine itself can still be kept running at its "native" speed, it's a reasonable approach to average the "raw" samples that fall between two "shadow memory" (software) samples, into each adjacent s/w sample, resulting in the observed increase in resolution. And that's just boxcar averaging.
So to cut a long story short, just the fact to find a higher than hardware resolution in down-sampled single shot traces indicates that some kind of boxcar averaging has been applied to decimate the ADC raw data.
how do you know its boxcar averaging?
This is quite easy: When doing a single shot trace of preset sample count and analyze the individual samples, you can easily see the quntization of the values (like the "bins" in a histogram). At 1.25MSa/s, 1V/div you will find a quantization of approx. 2.31mv, which, assuming a quantization of 12bits (as per Rigol's specs), results in a total peak-to-peak range of approx. 9.5V which easily matches the 8 vertical divisions (8V) of visible vertical range.
The same test with a sampling rate of 100kSa/s has a quantization of approx. 0.2875mV which leads to a resolution in the ballpark of 15 bits. Since in a single shot, the calculation of a classic "isotemporal" average isn't possible, and the sampling engine itself can still be kept running at its "native" speed, it's a reasonable approach to average the "raw" samples that fall between two "shadow memory" (software) samples, into each adjacent s/w sample, resulting in the observed increase in resolution. And that's just boxcar averaging.
So to cut a long story short, just the fact to find a higher than hardware resolution in down-sampled single shot traces indicates that some kind of boxcar averaging has been applied to decimate the ADC raw data.The basic question still stands, you have shown the quantisation levels improve with a lower acquisition sample rate but that only indicates some form of filtering. Boxcar is cheap/easy so probably the case, but it is not know to be boxcar yet (measure the frequency response out into aliasing to be sure which filter is used).
The basic question still stands, you have shown the quantisation levels improve with a lower acquisition sample rate but that only indicates some form of filtering. Boxcar is cheap/easy so probably the case, but it is not know to be boxcar yet (measure the frequency response out into aliasing to be sure which filter is used).
Are there any mods to these scopes yet to unlock bandwidth etc? I wonder if it's possible to copy the contents of the SD card to a faster card to perhaps improve boot times? In the eevblog video he said he couldn't read the contents of the card, maybe there is some software that will do a low-level copy of the content?
Using a mouse is more effective but wait, for this need you only have 1 USB A port and it seems from reports a USB hub will freeze the scope.
I've been using a mouse and USB stick on a cheap hub all week with no problems.
I just got a nicer hub and that works, too.