Rigol DHO804 Test and Compare Thread

[ebastler]

Stopband rejection is > 68 dB. I'm surprised that you seem to get more

Well, it rolls off to -80 dB or a bit better in your MatLab plot as you move further away from the peak. And that's about what TurboTom's screenshot also shows, right?

[gf]

Stopband rejection is > 68 dB. I'm surprised that you seem to get more

Well, it rolls off to -80 dB or a bit better in your MatLab plot as you move further away from the peak. And that's about what TurboTom's screenshot also shows, right?

That's not the reason. But my fault for not seeing immediately what was happening. Yes, the first side lobe is about -68dB. But the frequency response of the window function has zeros at +/-N*delta_f, where N is an integer >= 5. If the signal frequency is an integer multiple of delta_f, then the side lobes don't show up because the signal frequency hits the zeros between the lobes, so outside the main lobe, we only see the noise floor in the discretely sampled frequency spectrum. For signal frequencies which do hit the side lobes, we'll see the resulting "leakage".

Btw, the Siglent flattop window is possibly a different variant, having lower side lobes (handbook sais -93 dB; due to lack of the hardware I can't verify). This would also imply a wider main lobe.

[Performa01]

Earlier I took the 1khz reference signal as the source and went through all the windows.

Looks broken on your Rigol. And not just Flattop, the others look weird, too.

In order to show maximum leakage, don't choose exactly 1kHz, but rather 997.5 Hz in conjunction with your Rigol settings, and 998.97 Hz with your Siglent settings. IOW, us a frequency f = (N+0.5)*delta_f, where N is an integer. Calculate with enough decimal places, i.e. delta_f = 4.76837 and not just 4.77 for your Siglent settings.

FOr the SDS2000X Plus, this has already been done a while ago (reply #3561):

https://www.eevblog.com/forum/testgear/siglent-sds2000x-plus-coming/msg4318822/#msg4318822

Since the FFT core implementation is identical, I expect quite similar results from the SDS1104X-E.

[Performa01]

Btw, the Siglent flattop window is possibly a different variant, having lower side lobes (handbook sais -93 dB; due to lack of the hardware I can't verify). This would also imply a wider main lobe.

Indeed. The RBW of the Flattop window is 3.73 times the frequency step.

[gf]

FOr the SDS2000X Plus, this has already been done a while ago (reply #3561):
https://www.eevblog.com/forum/testgear/siglent-sds2000x-plus-coming/msg4318822/#msg4318822

Very nice! 
[ I obviously had a peek at it at the time, but I did not remember. ]

[core]

Oops, forget to switch off my DHO804, now it´s (nearly)24h burn-in proofed...

Earlier I took the 1khz reference signal as the source and went through all the windows.
Then I did the same with the Siglent SDS1104X-E, but of course I checked the 1khz reference again to see if there were any differences.
Here are the pictures.

I have replicated them on MSO5000, they are absolutely the same as HDO800. It seems that Rigol have no interest regarding FFT, no improvement after all these years.

[Mechatrommer]

Oops, forget to switch off my DHO804, now it´s (nearly)24h burn-in proofed...

i recommend you need to work more and have enough sleep to get better view/comparison... cheers.

[Martin72]

In order to show maximum leakage, don't choose exactly 1kHz, but rather 997.5 Hz in conjunction with your Rigol settings, and 998.97 Hz with your Siglent settings.

Did it with 997.5Hz.
Additional with 10ms/div = 6.25MSa/s.

Siglent will follow with 998.97Hz.

[voltsandjolts]

Is this the broken Rigol Flat Top or the fixed Flat Top? 

[Martin72]

Btw flat top...
Here a  siglent flat top pic with drastically reduced FFT-points.
I find the similarity with rigol's amazing.

[TurboTom]

Is this the broken Rigol Flat Top or the fixed Flat Top? 

@Martin72's flattop window function is still the broken (original) one, the repaired one (albeit on a DHO1000, hence a different sampling rate) is shown in the screenshot.

[2N3055]

To me, looking at (original) Rigol FFT windows, it looks like Flattop and Rectangular windows look pretty much the same.

[ebastler]

Btw flat top...
Here a  siglent flat top pic with drastically reduced FFT-points.
I find the similarity with rigol's amazing.

So -- is the assumption that the Rigol uses the full duration of the record, to get to the indicated small frequency step -- but reduces that dataset by undersampling (using only every n.th data point) or some similar scheme?

[Martin72]

To me, looking at (original) Rigol FFT windows, it looks like Flattop and Rectangular windows look pretty much the same.

Argh, I have to check, not that I made a mistake.
Thank you!

[Martin72]

@2N3055:

No, not a mistake...

[Fungus]

Note that you can set the channel labels to show the FFT window function in screenshots, it's what I did here:

[Martin72]

Good hint, hadn't had that in mind until then.

[Randy222]

My 804 just arrived from Aliexpress, it has firmware v00.01.02 dated Nov 9 2023.
It's not available as download on Rigol site.

What's new and/or fixed in 01.02 ?

[Fungus]

My 804 just arrived from Aliexpress, it has firmware v00.01.02 dated Nov 9 2023.
It's not available as download on Rigol site.

What's new and/or fixed in 01.02 ?

Not much.

Code: [Select]


v00.01.02.00.00  2023/11/2

1. Self calibration optimization update
2. Solve the problem of UltraLab startup connection failure
3. Solve the problem of failure to save waveform in wfm format
4. Add education model equivalent settings
5. Solve the problem of unresponsive touch on startup screen

v00.01.01.00.02 2023/09/12

1. Self calibration optimization update
2. Update Help Documents

v00.01.01.00.01  2023/08/10

1. Remove all time-related displays on the instrument
2. To modify the vertical interface, click the wiring diagram to modify the AC coupling function
3. Modify the delayed scan Chinese display as Zoom
4. Modify the order of the menu in the upper right corner, put the measurement in the front and Default in the back
5. The probe ratio interface is removed, and the probe ratio option is added to the vertical first-level menu


v00.01.00.00.19  2023/07/24

1. The first version is released


[Serg65536]

I use firmware 1.02, it's not available for download now. Nothing critical was fixed in this version.
See more here: https://www.eevblog.com/forum/testgear/hacking-the-rigol-dho800900-scope/msg5173176/#msg5173176

[Randy222]

My 804 just arrived from Aliexpress, it has firmware v00.01.02 dated Nov 9 2023.
It's not available as download on Rigol site.

What's new and/or fixed in 01.02 ?

Not much.

Code: [Select]


v00.01.02.00.00  2023/11/2

1. Self calibration optimization update
2. Solve the problem of UltraLab startup connection failure
3. Solve the problem of failure to save waveform in wfm format
4. Add education model equivalent settings
5. Solve the problem of unresponsive touch on startup screen

v00.01.01.00.02 2023/09/12

1. Self calibration optimization update
2. Update Help Documents

v00.01.01.00.01  2023/08/10

1. Remove all time-related displays on the instrument
2. To modify the vertical interface, click the wiring diagram to modify the AC coupling function
3. Modify the delayed scan Chinese display as Zoom
4. Modify the order of the menu in the upper right corner, put the measurement in the front and Default in the back
5. The probe ratio interface is removed, and the probe ratio option is added to the vertical first-level menu


v00.01.00.00.19  2023/07/24

1. The first version is released


What's the meaning of v00.01.02.00.00  2023/11/2 date "Nov 2 2023"? Is that when the release note was made, or something other. My 804 shows one week later.

[ebastler]

What's the meaning of v00.01.02.00.00  2023/11/2 date "Nov 2 2023"? Is that when the release note was made, or something other. My 804 shows one week later.

Never mind, a one week difference is spot-on for Rigol. They are not good with dates. Some of the release dates you find on their international sites are off by months, in either direction.

[Martin72]

I think that's how it will be, first the notes, then the "release".
However, I also think that this version, which has since been withdrawn, only applies to certain hardware configurations* - they probably had to make improvements and this does not apply to all variants.
This also explains why my DHO couldn't cope with the firmware and I "deleted" it again.
*) Due to component shortages, alternative elements were presumably used that required correction.

[rpro]

Note that you can set the channel labels to show the FFT window function in screenshots....

Also, while we wait for Rigol to add basic averaging features to their FFT, one can use pyvisa to acquire traces from the scope and display the avg result with a few lines of python code. Here is a minimalist working example:

import pyvisa as visa 
import matplotlib.pyplot as plt
import numpy as np

scopedev = 'TCPIP0::192.168.0.10::5555::SOCKET'  #four 5's
nSamples = 100

scope = visa.ResourceManager().open_resource(scopedev)
scope.read_termination = scope.write_termination = '\n'
print("Scope: ", scope.query("*IDN?"))

scope.write(":WAV:SOURCE MATH1;:WAV:FORM ASCii;:WAV:MODE NORMAL")
fstart = float(scope.query(":MATH1:FFT:FREQuency:START?"))
fend = float(scope.query(":MATH1:FFT:FREQuency:END?"))

X = np.linspace(fstart, fend, 1000, endpoint=True)/1e6
fftData =[]
for i in range(0,nSamples):
    fftData += [np.array(scope.query(":WAV:DATA?").split(","),dtype=float)]

avgFFTdata = np.mean(np.array(fftData),axis=0)
plt.plot(X,avgFFTdata)
plt.grid(True, which="both")
plt.show()

[Martin72]

Hi,

Just for fun, the boot times of the three little pi...no, scopes.
I was comparing something else and thought to myself, oh, just make a clip.
I personally don't care about the boot time, I hate it with multimeters and recently also with power supplies.