Rigol DHO804 Test and Compare Thread

[2N3055]

So to cut a long story short, consider the DHO800/900 with more than two channels active to be a 100MHz scope, and you are on the safe side.

That's obvious from the sample rate.

If it makes much sense to spend the premium on the DHO924(S) can definitely be questioned. I probably wouldn't even apply a hack regarding the frequency upgrade if one should become available.

It's a 250MHz 'scope when there's only one/two channels enabled.

If you:
a) Work with 50 Ohm stuff and know to stick to two channels when doing that.
b) Need four channels for working with probes at other times.

Then ... it might be worth it.

For everybody else? Probably not.

You seem to forget what I warned you about.

If scope keeps full 250MHz BW while decreasing it's sample rate to 312.5 MSp/s that is bad design.

If scope knows sample rate is insufficient, it should enable antialiasing filters to prevent aliasing.
Scope should drop to 100Mhz (or 70MHz) BW if needed to prevent aliasing and show that on screen.

Saying it is 250 MHz 4 ch scope is firstly lying trough your teeth, second is going to get users in trouble.
Especially because target market are hobby/beginner users...

Signals that have BW in excess of 100 MHz are very common today. Arduino has less than 1ns edges on outputs and RaspberryPI has them several times faster...

[DaneLaw]

Looking at screenshots from various scope brands on the web, they all seem to show color grading without putting intensity grading on top, and I think that is what you want for clarity.

For clarity?.. it's a scope, you want "information", and whatever that can visualize that information, the better.
and what do you mean by "puttng on intensity"? it's a grading that scales the signal intensity'  so you in fact get better clarity.
It's exactly what you want, for "clarity.
I do recall that mid to higher-end models, will often let you work with the intensity grading, also in color-corrected mode, which I find very handy, but you mention you have been looking at screenshots online, likely not the best approach to sense levels...maybe take a look on YT.

A good intensity grading is a must for a modern digital bench scope, it would be a shame if it's not up to par with the latest Rigol entry DS1000Z series with 64 levels., but it's a new model, so it will evolve, be optimized.
Would puzzle me, if DSO800 & 900 don't build on, pretty much all factors vs their older entry model.

Actually, I still like the intensity grading of the DS1000Z series better, not to speak of the higher models of this heritage...

What 7" LCD panel are Rigol using in DHO800 & DHO900 series? TFT or IPS?

[csuhi17]

Which does not rule out the possibility that some scopes may let you combine both grading modes, and their combined use is just never shwon in screenshots. Anyone with hands-on experience who can comment?

Did you mean this effect??
Micsig STO2202C

[TurboTom]

I find a lot of spurious signal at 1/8 of the sampling frequency superimposed to low-level signals -- Here's 1MHz 8mVpp sine fed to channel 1. and the FFT of the waveform. I know this is scraping at the edge of the intended envelope of this instrument, but interesting to know anyway. It may point in the direction of asymmetries between the individual sctions of the pipelined ADC...

Okay, seems like the forum's file upload is working again 

In between I made a new observation that alleviates the previous apparent problem: I've been using a 90cm BNC cable to connect the DHO914S's AWG output to channel 1 input without termination. It may have well been possible that this contraption has a resonance frequency close to the 156.25MHz which is 1/8 Fs, that may have been excited by some leakage of this signal from the scope. Using a short cable (30cm) and proper termination reduces this spurious signal considerably, see RigolDS43. So probably nothing to worry about here... 

[ebastler]

For clarity?.. it's a scope, you want "information", and whatever that can visualize that information, the better.
and what do you mean by "puttng on intensity"? it's a grading that scales the signal intensity'  so you in fact get better clarity.
It's exactly what you want, for "clarity.

If I want to see frequent and rare signals, intensity grading will limit the dynamic range of "rareness": Very infrequent signals will become invisibly dim, or frequent signals will saturate. That's where I think color grading is most useful -- it lets the scope visualize that larger dynamic range on a color scale. But making the infrequent traces not only blue, but also very dim, seems to negate that benefit?

I do recall that mid to higher-end models, will often let you work with the intensity grading, also in color-corrected mode

What do you mean by "color-corrected" mode? Are we really talking about the same thing, i.e. false color or heatmap encoding?

A good intensity grading is a must for a modern digital bench scope, it would be a shame if it's not up to par with the latest Rigol entry DS1000Z series with 64 levels.

I certainly agree, as far as (pure) intensity grading is concerned. As mentioned earlier, the datasheet does specify "real-time 256-level intensity grading" for the DHO 800/900 scopes. So let's hope that is what we actually get -- eventually maybe, if and when properly implemented in software...

[2N3055]

In color grading mode, Intensity button usually controls color saturation.  Since not all colors are perceived by eye as same brightness  there could be illusion of varied brightness.

The problem here is that it seems that 16 or less levels are used to render waveforms.

[ebastler]

The problem here is that it seems that 16 or less levels are used to render waveforms.

Agreed, if that should indeed be the case (for intensity grading), it would be very disappointing. But it is not the problem I -- and I believe DaneLaw too -- were discussing. Rather, I was referring to:

Quick and dirty, intensity grading....looks very good.
But switching to color grade mode will deactivate the intensity adjustment.

Which, I thought, is the normal way of doing color grading. If it not only deactivates intensity adjustment, but also does not allow any adjustment of the color scale as you described, that would indeed be annoying.

[DaneLaw]

For clarity?.. it's a scope, you want "information", and whatever that can visualize that information, the better.
and what do you mean by "puttng on intensity"? it's a grading that scales the signal intensity'  so you in fact get better clarity.
It's exactly what you want, for "clarity.

If I want to see frequent and rare signals, intensity grading will limit the dynamic range of "rareness": Very infrequent signals will become invisibly dim, or frequent signals will saturate. That's where I think color grading is most useful -- it lets the scope visualize that larger dynamic range on a color scale. But making the infrequent traces not only blue, but also very dim, seems to negate that benefit?

I do recall that mid to higher-end models, will often let you work with the intensity grading, also in color-corrected mode

What do you mean by "color-corrected" mode? Are we really talking about the same thing, i.e. false color or heatmap encoding?

The specific comment you replied & commented on #40 - had two long videos of this exact feature, so not sure why you're unsure what we are talking about.
It goes under tons of different names & labels from vendor to vendor, some call it "heatmap" some calls its "color grading", some call it "Color Corrected Temperature" and some just label it as CCT, it goes under a lot of different names.

The videos on the comment you replied to, are done with a Micsig scope, and Micsig labels it as Color Corrrected Temperature, (CCT) and gives full intensity grading in CCT mode, as you can see in the context, so it shouldn't be up for debate what we are talking about.
https://www.eevblog.com/forum/testgear/rigol-dho804-test-and-compare-thread/msg5106732/#msg5106732

There is also a screen dump above your comment #52 highlighting it.

If I want to see frequent and rare signals, intensity grading will limit the dynamic range of "rareness": Very infrequent signals will become invisibly dim, or frequent signals will saturate. That's where I think color grading is most useful -- it lets the scope visualize that larger dynamic range on a color scale. But making the infrequent traces not only blue, but also very dim, seems to negate that benefit?

The aspect of rareness, and being able to decipher that, is the exact thing you get with intensity grading, and the more levels the better, as it will segment the waveform into "rareness" as you adjust the intensity accordingly.
Its an extremely useful feature to decipher the information in a given waveform and how present they are.

It's not plug-and-play..like with all meters you will get familiar with your scope, and adjust it accordingly, so don't worry about "rareness" disappearing.. it aint, quite the contrary, it will show you which part of the signal is "rare" - if you adjust & monitor it accordingly...having features that can segment the information in the waveform is quite handy, both in single color and in a color palette, that again will grade each color into many tone-levels, as you can see in the video, how "blue" starts out, very dark royal blue, and toning into a lighter blue shade, flipping over to light green, and vice versa down the wavelength scale.

One thing that would be nice add on to CCT - is like I have on my thermal cameras, where I can make up my own color palette from scratch,  like I also got on certain spectrum waterfalls.

[nctnico]

For clarity?.. it's a scope, you want "information", and whatever that can visualize that information, the better.
and what do you mean by "puttng on intensity"? it's a grading that scales the signal intensity'  so you in fact get better clarity.
It's exactly what you want, for "clarity.

If I want to see frequent and rare signals, intensity grading will limit the dynamic range of "rareness": Very infrequent signals will become invisibly dim, or frequent signals will saturate. That's where I think color grading is most useful -- it lets the scope visualize that larger dynamic range on a color scale. But making the infrequent traces not only blue, but also very dim, seems to negate that benefit?

I agree. Making infrequent signals dim is pretty useless. It only serves mimicking analog scope like behaviour while forgetting the main problem of analog scopes is that they hardly show infrequent signals.  At my first employer I had an analog Hameg scope with overrange indicators (LEDs). I used those regulary to catch pulses which where invisible on the screen.

When I want to see infrequent signals I use infinite persistence, color grading or reverse intensity (the latter is a feature I've only seen & used on R&S scopes).

[Fungus]

You seem to forget what I warned you about.

Huh?

Scope should drop to 100Mhz (or 70MHz) BW if needed to prevent aliasing and show that on screen.

I've been saying that for months (and you know it).

[ebastler]

The specific comment you replied & commented on #40 - had two long videos of this exact feature, so not sure why you're unsure what we are talking about.

I must admit that I did not make it far into the videos, sorry! Long silent films where I am expected to stare at the screen and figure out what is happening and what the message is don't work well for me. But yes -- we are talking about he same thing, color grading or whatever. Thanks for confirming.

It goes under tons of different names & labels from vendor to vendor, some call it "heatmap" some calls its "color grading", some call it "Color Corrected Temperature" and some just label it as CCT, it goes under a lot of different names.

Actually no-one (including MicSig) calls it "color corrected mode" or "color corrected temperature". CCT apparently stands for color-correlated temperature (*), which makes more sense to me.  "Color temperature correction" is an entirely different thing in photography; hope you can understand where my confusion came from.

Regarding the benefit (or lack thereof) of showing intensity grading at the same time as color grading, you and I still seem to talk at cross-purposes. I am reassured to see nctnico's comment, and also 2N3055's pointing out that "In color grading mode, Intensity button usually controls color saturation". I certainly see the benefit of that.

(*) Edit: Actually I can't find any documents where MicSig themselves use the "CCT" acronym or spell it out. The "correlated color temperature" meaning seems to come from a different discipline too, unrelated to false color scales. I stand correlated. 

[2N3055]

In color grading mode, some scopes have option to change between different color palettes (color ranges and color mapping).
As Nico said, interesting mode is inverse palette (both color and intensity grading) where signal is rendered brighter/hotter color when it is RARE (repeating rarely) to make it easier to see...

There are also different color grading plot types: density plot, pixel frequency plot, phosphorus emulation....

[DaneLaw]

sorry! Long silent films where I am expected to stare at the screen and figure out what is happening and what the message is don't work well for m
Actually no-one (including MicSig) calls it "color corrected mode" or "color corrected temperature".  "Color temperature

As explained, a few times now.. a lot of different labels are used amongst scope vendors for the "color temperature" function.
Micsig uses
"color temperature mode" STOxxxC/E
"correlated color temperature" STOxxxC/E (CCT)
"color temperature open mode" STOxxxC/E
"color temperature display" (ETO/MDO)


So the simple wording "color temperature" should cut it.. (color corrected or not)
and dear, what you wanna see or don't in a given comment, got little bearing, when it's the first few seconds, so one would take for granted that you at least related the content on the exact comment you replying to - when there is even an example there for the claim your making'..  one even got a tune for your pleasure for short focus-span.. next time I will give you a timestamp +0.00sec.
but let's move, been explained back and forward in both words, visual and screen dumps from other users.
you stated that color intensity temperature grading, aint a feature that you have seen on scopes, and you came to that conclusion after you have been looking at many screenshots on Google/web.

Looking at screenshots from various scope brands on the web, they all seem to show color grading ]without putting intensity grading on top, and I think that is what you want for clarity.

Tried to explain that wasn't the case and so did others, alongside WHY I find it very useful as it gives me more information on the signal I am looking at..
but as mentioned, let's move on...

Personally, I would love to see a shootout from Dave on the intensity grading on modern scopes, and how they stack up, current Rigol DHO800/1000/4000, R&S2 & 4series, Tek2 series, and what abilities they each have, also in color temperature mode.

//

(*) Edit: Actually I can't find any documents where MicSig themselves use the "CCT" acronym or spell it out. The "correlated color temperature" meaning seems to come from a different discipline too, unrelated to false color scales.

Its Micsig'slabel in the OS-menu/display/waveform "CCT"..you can see it in the first post... and "correlated color temperature" [CCT] does confuse, as it very common label  in lighting for light temperature, but in newer models like ETO/MDO.. it seems be exchanged for "Color temperature display" but this aint a Micsig thread.

[TurboTom]

The "noise signal" output of the "S"-Model's  AWG appears to be very decent. The valley at 78.125MHz indicates the Nyquist frequency (due to a DAC sample rate of 156.25MHz = 1/8 Fs of the scope's ADC). Unfortunately, there's quite some amount of the sampling frequency leaking through to the AWG output (and it's not related to the scope section's ADC as I assumed in this contribution).

Considering these figures, I'm a little bit surprised that Rigol limited this AWG to 25MHz, the reconstruction filter and the other components appear to be laid out for a 50MHz AWG. Also the noise signal output appears to indicate this. So we may actually be up to a surprise eventually. For a "real" 25MHz AWG, I would have expected the reconstruction filter to be configured for a lower cut-off frequency with a steeper slope...

Btw, I like the handling and the speed of the scope's FFT along with the overall responsiveness of the U/I. That's quite an improvement vs. the "legacy" models. Once the problems are ironed out, this is going to be a nice instrument.

[DaneLaw]

The "noise signal" output of the "S"-Model's  AWG appears to be very decent. The valley at 78.125MHz indicates the Nyquist frequency (due to a DAC sample rate of 156.25MHz = 1/8 Fs of the scope's ADC). Unfortunately, there's quite some amount of the sampling frequency leaking through to the AWG output (and it's not related to the scope section's ADC as I assumed in this contribution).

Considering these figures, I'm a little bit surprised that Rigol limited this AWG to 25MHz, the reconstruction filter and the other components appear to be laid out for a 50MHz AWG. Also the noise signal output appears to indicate this. So we may actually be up to a surprise eventually. For a "real" 25MHz AWG, I would have expected the reconstruction filter to be configured for a lower cut-off frequency with a steeper slope...

Btw, I like the handling and the speed of the scope's FFT along with the overall responsiveness of the U/I. That's quite an improvement vs. the "legacy" models. Once the problems are ironed out, this is going to be a nice instrument.

Its a bargain for the price, does the display have any off-center axis to conclude if its TFT or IPS LCD?
not that is meens much, as a good TFT is prefered over a bad IPS and vice versa but the TFT could be a problem from certain angles if people got it up on a VESA mount/arm

[ebastler]

Which does not rule out the possibility that some scopes may let you combine both grading modes, and their combined use is just never shwon in screenshots. Anyone with hands-on experience who can comment?

Did you mean this effect??
Micsig STO2202C

Thanks! The attachments finally showed up now, after what appeared to be some forum glitch.

The first picture seems to use intensity grading to extend the color grading scale towards the low end: There's blue for less frequent signals, and dark blue for even rarer signals. That's a nice way of doing it, which I had not (consciously) come across before.

The other two pictures, at least to my eyes, show pure color grading: The information is in the color, I don't perceive additional information in intensity variations. That's what I had typically seen before.

All three pictures nicely illustrate what 2N3055 pointed out, namely that the "intensity" slider actually shifts the color scale in this mode. Which apparently it cannot do in the Rigol DHO models, since it gets disabled entirely -- that's a pity.

My preliminary takeaways regarding "grading" on the DHO 800/900 are:

• It does do intensity grading. Specified as 256 levels in the datasheet, looking good in screen captures on the PC (Martin72), looking less convincing on actual photos of the built-in screen (TurboTom).
• It does color grading. Looking alright if the fixed color scale is a good match (Martin72), but offering little or no flexibility to tweak it. Various other scopes offer more flexibility, notably among entry-level scopes the MicSigs.

[Fungus]

Btw, I like the handling and the speed of the scope's FFT along with the overall responsiveness of the U/I. That's quite an improvement vs. the "legacy" models. Once the problems are ironed out, this is going to be a nice instrument.

Also the windowing feature which nobody seems to mention. Having two full height signal displays without overlay (as shown above) seems like a huge benefit.

[Martin72]

Rigol MSO 5000 and Siglent models could do this.
The first I've shown here long ago, the second I could post it here in the later evening.

Pics from the SDS2104X+ at work and the SDS1104X-E at home.

[Martin72]

Having two full height signal displays without overlay (as shown above) seems like a huge benefit.

This only makes the small screen smaller, which you soon need a magnifying glass.
But I'm still testing how practical this function is.
Edit:
Forgot the pics with 5ms timebase from the 1104X-E...

[2N3055]

Btw, I like the handling and the speed of the scope's FFT along with the overall responsiveness of the U/I. That's quite an improvement vs. the "legacy" models. Once the problems are ironed out, this is going to be a nice instrument.

Also the windowing feature which nobody seems to mention. Having two full height signal displays without overlay (as shown above) seems like a huge benefit.

You have that function on many other scopes. You just didn't have opportunity to try out more than few scopes that you had.
And as Martin says, other manufacturers usually split screen horizontally, because X axis carries more details.
Also decoding in vertical window on 7" screen sounds quite claustrophobic.

[Martin72]

other manufacturers usually split screen horizontally, because X axis carries more details.

You can move the windows..

[Martin72]

You can move the windows..

Like this...
Vertical view is on this tiny screen not recommendable(my opinion)..

[2N3055]

Which does not rule out the possibility that some scopes may let you combine both grading modes, and their combined use is just never shwon in screenshots. Anyone with hands-on experience who can comment?

Did you mean this effect??
Micsig STO2202C

Thanks! The attachments finally showed up now, after what appeared to be some forum glitch.

The first picture seems to use intensity grading to extend the color grading scale towards the low end: There's blue for less frequent signals, and dark blue for even rarer signals. That's a nice way of doing it, which I had not (consciously) come across before.

The other two pictures, at least to my eyes, show pure color grading: The information is in the color, I don't perceive additional information in intensity variations. That's what I had typically seen before.

All three pictures nicely illustrate what 2N3055 pointed out, namely that the "intensity" slider actually shifts the color scale in this mode. Which apparently it cannot do in the Rigol DHO models, since it gets disabled entirely -- that's a pity.

My preliminary takeaways regarding "grading" on the DHO 800/900 are:

• It does do intensity grading. Specified as 256 levels in the datasheet, looking good in screen captures on the PC (Martin72), looking less convincing on actual photos of the built-in screen (TurboTom).
• It does color grading. Looking alright if the fixed color scale is a good match (Martin72), but offering little or no flexibility to tweak it. Various other scopes offer more flexibility, notably among entry-level scopes the MicSigs.

Well said.
In addition, and as a reply to @DaneLaw, color grading has been called all kinds of things, for all kinds of marketing reasons.

History of intensity grading starts with phosphorus emulation. If electron beam stayed in one place longer, that part of screen shone brighter. Brightest part of trace was achieved on any time base if there was no signal and we had only horizontal sweep by timebase. As soon as there was signal, electron gun has to swep in both X and Y. Parts where we had fast edge, trace was barely visible. There was also phosphorus persistence, so if signal repeated  faster than decay it was brighter....
Since people demanded from manufacturers that digital scopes display signals more like they were used to, varios phosphorus emulations were created.

Most of the intensity grading was just that, with caveat that you can create nonlinear response, so eye still feels like it is "analog" but you don't let parts of trace go invisible..
But still we have paradox that rare events (that might be the ones we are looking for) are least visible.
Also intensity is very much based on individual perception.  There is limited amount of statistical info that can be extracted from looking at it.

Here we enter color grading.  All statistical info about how much time signal spent in certain place and/or traversed through same place is converted to color palette..
Some of the names mentioned have no root in manufacturer calling this feature "color temperature" or something.
Those names come from color encoded graphs in other parts of human activity, where colored graphs are abundant.
Those are actually names of palettes. There are color palettes that are coded by color temperature (black body temp-color mapping), some have other color mappings.

[2N3055]

You can move the windows..

Like this...
Vertical view is on this tiny screen not recommendable(my opinion)..

That is good news!!

[Performa01]

other manufacturers usually split screen horizontally, because X axis carries more details.

You can move the windows..

Welll, member 2N3055 and me are used to that, since we have PicoScopes.

Movable windows are great - if they are flexible, i.e. you can have as many windows you need (and like), can resize them to any form factor you prefer and have a large screen to arange them. That describes a PicoScope on a decent PC workstation.

Things are very different for a tiny little instrument with tiny screen: there I cannot benefit from multiple freely resizable windows, as there is simply no space for them. Quite the contrary, I want a clever layout of the UI, as little waste of precious screen space as possible, hence no window frames, no wide symbol bars and no playful menus.

You have the SDS2000X HD. Turn it on, let the side menu disappear and then compare the relation of the screen area available for signal display and measurement results to the space taken up by the top menu bar and the channel cards at the bottom. Am I the only one who spots the difference? And the SDS2000X HD has a big screen by comparison.