Author Topic: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope  (Read 67603 times)

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Offline Martin72

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #625 on: March 07, 2019, 08:37:54 am »
Here my wishlist for further firmware upgrades ( will be send to rigol too):

- A useable hi-res mode, like keysight, lecroy and even siglent have it

- All math functions could be displayed "stand alone" and/or:

- Split screen modes, for every channel, for every math function - This would be a real benefit - None provide it in this priceclass an wide above. ( so it will be a wish I guess)

- Free choosable colours for all traces - Math got one colour only, unfortunately "dark violet", what makes no sense in aspect to the dark screen.

- A free adjustable measure gate, "free" moveable on the screen ( you define a gate and could this one scroll to the whole screen- it measures only whats in the gate, known from older lecroy waverunner scopes)

- Bode plot function, makes really sense when you already got a build in wavegenerator (will come)

- Brighter Display (will come)





 

Offline el_man

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #626 on: March 07, 2019, 09:55:58 am »
Here my wishlist for further firmware upgrades ( will be send to rigol too):

- A useable hi-res mode, like keysight, lecroy and even siglent have it

- All math functions could be displayed "stand alone" and/or:

- Split screen modes, for every channel, for every math function - This would be a real benefit - None provide it in this priceclass an wide above. ( so it will be a wish I guess)

- Free choosable colours for all traces - Math got one colour only, unfortunately "dark violet", what makes no sense in aspect to the dark screen.

- A free adjustable measure gate, "free" moveable on the screen ( you define a gate and could this one scroll to the whole screen- it measures only whats in the gate, known from older lecroy waverunner scopes)

- Bode plot function, makes really sense when you already got a build in wavegenerator (will come)

- Brighter Display (will come)

Nice post Martin72

and if it is possible some more from me (arranged by priority)

1. Adjustable transparency to the floating windows - in some modes, like power analyzes, they almost cover the entire screen

2. In FFT mode the grid scale instead of time can show the frequency scale related to FFT diagram

3. A more reliable XY-mode with ability to show the waveforms along with diagram (as at DS1054Z) and option to choose which channels are involved, now it is fixed to ch1 and ch2



« Last Edit: March 07, 2019, 10:57:44 am by el_man »
 

Offline David Hess

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #627 on: March 07, 2019, 12:06:16 pm »
I would like an RMS measurement function which actually measures RMS like my 30 year old Tektronix DSO can.  How could Rigol continuously get it wrong 30 years later?

You mean the MSO5000 doesn't have real peak detection?

No, the MSO5000 series probably has peak detection but earlier DSOs from Rigol before the DS1000Z series did not despite their documentation saying and continuing to say they do.  This leads to the confusion where peak detection means two different things depending on which Rigol DSO you are using or which documentation you are reading.

 

Offline Martin72

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #628 on: March 08, 2019, 09:13:20 am »
I would like an RMS measurement function which actually measures RMS like my 30 year old Tektronix DSO can.  How could Rigol continuously get it wrong 30 years later?

Real measurement ? Please explain….
 

Offline TK

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #629 on: March 09, 2019, 01:53:54 pm »
Something is really messed-up with the front-end of the MSO5000.  I am using a 10KHz sinewave generated by the builtin AWG, BNC to crocodile, 10X Rigol probe.  In Normal acquisition mode, I cannot get a stable signal, it is triggering in both directions, rising and falling edge.  When I switch to average mode with 2 averages, the signal gets attenuated by more than 50%, then Hi-Res acquisition mode brings back the signal to full, but the double triggering disappears.  I use the same cable with the Rigol probe on my Keysight EDUX1002G and it works perfectly, as expected.

Can anyone try the same setup and verify?

MSO5K normal


MSO5K average


MSO5K HiRes


1000X Normal


1000X average


1000X HiRes


EDIT: changed 1KHz to 10KHz in my post.  Thanks Martin72
« Last Edit: March 10, 2019, 12:17:30 am by TK »
 

Offline David Hess

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #630 on: March 09, 2019, 05:24:12 pm »
I would like an RMS measurement function which actually measures RMS like my 30 year old Tektronix DSO can.  How could Rigol continuously get it wrong 30 years later?

Real measurement ? Please explain….

RMS measurements on the Rigol do not measure RMS accurately when many equal value frequency components are present.  Specifically, the Rigol cannot measure RMS noise which would be done for signal to noise or spot noise measurements.  I suspect this is caused by performing the RMS measurement on the display record which has been processed to combine multiple acquisitions likely destroying the RMS value.  It is not clear if this problem exists when only a single acquisition is displayed.

This also would explain why some measurements change value when a waveform is saved.

Someone measuring relatively noise free waveforms like phase control outputs or common waveforms would likely never notice.
« Last Edit: March 09, 2019, 05:26:42 pm by David Hess »
 

Offline 2N3055

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #631 on: March 09, 2019, 09:36:12 pm »
Quote from: David Hess/
David, old Rigols did RMS over highly decimated screen pixel data. That resulted in measurents being made over filtered /distorted data.
 New ones do it either over 1MP or full buffer, so they should do it very well. But it is good that you reminded us about that. Someone with the scope could verify it. What do you think, what would be proper protocol to verify that RMS works well this time?
Regards
Sinisa
« Last Edit: March 10, 2019, 01:19:09 am by 2N3055 »
 

Offline Martin72

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #632 on: March 10, 2019, 12:13:49 am »
Quote
Can anyone try the same setup and verify?

Monday, but with an external gen.

Quote
I am using a 1KHz sinewave

Looks like 10Khz...

Quote
BNC to crocodile, 10X Rigol probe.

And what about a direct connection, bnc to bnc, same probs ?
 

Offline TK

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #633 on: March 10, 2019, 12:32:12 am »
Quote
I am using a 1KHz sinewave

Looks like 10Khz...
You are correct, 10KHz

Quote
BNC to crocodile, 10X Rigol probe.

And what about a direct connection, bnc to bnc, same probs ?
BNC to BNC works OK
 

Offline TK

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #634 on: March 10, 2019, 12:51:05 am »
I have a suspicion of what is happening... this morning my EDUX1002G started doing a similar thing, but less frequent.  It is the noisy signal that is triggering when the sinewave is falling, but because of the noise level, it detects the noise rising portion of the signal.

I was able to capture a trigger on a falling edge of the sinewave with the Trigger set to rising edge.  I also changed the BNC fixture to discard a bad cable, I used a simple BNC with 50ohm cable and attached the probes to the end

I still get 50% reduction when acquire mode is set to average with 2 averages.  I also suspect it is because of the noisy input.  I see this 50% reduced signal on the scope, then I press SINGLE capture button and it shows a sinewave with the full Vpp.  But if I press STOP, it still shows the 50% reduced signal.

We need the experts opinion on why this could be happening.  Due to my limited knowledge, I cannot find a clear answer.

False trigger


BNC Fixture


Average acquisition, trigger RUN


Average acquisition, SINGLE trigger






« Last Edit: March 10, 2019, 01:11:26 am by TK »
 

Offline 2N3055

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #635 on: March 10, 2019, 01:24:51 am »
Try seting holdoff. Also try enabling high freq rejection trigger and set propper cutoff..
 

Offline kahuna0k

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #636 on: March 10, 2019, 11:38:17 am »
I'm having issues measuring the amplitude of a 120Mhz sine wave generated by an "improved" Siglent SDG2042X. Connecting a 1.5m coax with an inline 50Ohm termination and setting the output of the generator to 50Ohm, 5Vpp, I get ~4.25Vpp in the hacked Rigol MSO5074, but 4.8Vpp in my (also hacked) Siglent SDS1104X-E. I've tried self calibrating both, with no improvement. I supposed that if the hack wouldn't work I should get a much lower amplitude than 4.25Vpp at 120Mhz. Maybe the cable is not the best (random Amazon's RG58) but I've tried with a shorter (around 70cm) with the same result.

Any idea about what's going on?
 

Online nctnico

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #637 on: March 10, 2019, 11:58:59 am »
At these frequency the response likely isn't flat. Also an inline terminator isn't the best thing to use. As a rule of thumb: if you measure any signal over 100MHz forget about using 1M Ohm inputs and high impedance probes. You won't get accurate results.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 
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Offline tautech

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #638 on: March 10, 2019, 01:06:31 pm »
I'm having issues measuring the amplitude of a 120Mhz sine wave generated by an "improved" Siglent SDG2042X. Connecting a 1.5m coax with an inline 50Ohm termination and setting the output of the generator to 50Ohm, 5Vpp, I get ~4.25Vpp in the hacked Rigol MSO5074, but 4.8Vpp in my (also hacked) Siglent SDS1104X-E.
Any idea about what's going on?
~120 MHz is the -3dB point for the SDS1104X-E so that's why P-P is a bit lower than expected.
Hacked it should be ~230 MHz.
But as nctnico has said, frequency response is not perfectly flat over the full range and inline terminators are not all equal.  ;)

Try using 1V P-P and shifting the frequency towards 120 MHz on your SDG to where you see 0.707V which is the theoretical -3dB point. Also allow for the amplitude accuracy spec for both scope and AWG from their datasheets.
You might even be able to use a slow AWG sweep setting and a slow time base to see this.
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Offline Shodge

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #639 on: March 10, 2019, 03:41:32 pm »
I assume you are using infinite persistence to show this?  I kind of noticed this with trigger levels below 1V previously, but as I was looking at digital signals - I assumed the noise was there.

My scope does this but is not consistent.  With infinite persistence, I can demonstrate it in 1-2 secs.

I am using the latest firmware - 04.04, AWG source and I tried both 1Khz and 10Khz.  1Khz seem a little worse.  On my scope, I can go to the trigger menu and turn on Noise Reject and it completely goes away.

My conclusion is that the scope has a noisy trigger... (see if this addresses your issue)

-Stan
 

Offline kahuna0k

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #640 on: March 10, 2019, 06:19:51 pm »
I'm having issues measuring the amplitude of a 120Mhz sine wave generated by an "improved" Siglent SDG2042X. Connecting a 1.5m coax with an inline 50Ohm termination and setting the output of the generator to 50Ohm, 5Vpp, I get ~4.25Vpp in the hacked Rigol MSO5074, but 4.8Vpp in my (also hacked) Siglent SDS1104X-E.
Any idea about what's going on?
~120 MHz is the -3dB point for the SDS1104X-E so that's why P-P is a bit lower than expected.
Hacked it should be ~230 MHz.
But as nctnico has said, frequency response is not perfectly flat over the full range and inline terminators are not all equal.  ;)

Try using 1V P-P and shifting the frequency towards 120 MHz on your SDG to where you see 0.707V which is the theoretical -3dB point. Also allow for the amplitude accuracy spec for both scope and AWG from their datasheets.
You might even be able to use a slow AWG sweep setting and a slow time base to see this.

What I don't understand is that the hacked SDS1104X-E (200MHz) gives me more amplitude than the hacked MSO5074 (350MHz). Even at 50MHz, the SDS1104X-E measures 4.94V but the MSO5074 measures 4.7V, and this is using the same cable and the same inline terminator. While the Siglent is very consistent between 1MHz and 120MHz, the Rigol goes from ~5V to 4.3V from 1MHz to 120MHz.

When you say that the response is not flat, you mean the response of the oscilloscope? I would expect a 350Mhz scope to be able to measure with some accuracy the amplitude of a 120Mhz sine wave, if not what should I do? Could it be a defective unit?
 

Offline tautech

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #641 on: March 10, 2019, 07:53:40 pm »
I'm having issues measuring the amplitude of a 120Mhz sine wave generated by an "improved" Siglent SDG2042X. Connecting a 1.5m coax with an inline 50Ohm termination and setting the output of the generator to 50Ohm, 5Vpp, I get ~4.25Vpp in the hacked Rigol MSO5074, but 4.8Vpp in my (also hacked) Siglent SDS1104X-E.
Any idea about what's going on?
~120 MHz is the -3dB point for the SDS1104X-E so that's why P-P is a bit lower than expected.
Hacked it should be ~230 MHz.
But as nctnico has said, frequency response is not perfectly flat over the full range and inline terminators are not all equal.  ;)

Try using 1V P-P and shifting the frequency towards 120 MHz on your SDG to where you see 0.707V which is the theoretical -3dB point. Also allow for the amplitude accuracy spec for both scope and AWG from their datasheets.
You might even be able to use a slow AWG sweep setting and a slow time base to see this.

What I don't understand is that the hacked SDS1104X-E (200MHz) gives me more amplitude than the hacked MSO5074 (350MHz). Even at 50MHz, the SDS1104X-E measures 4.94V but the MSO5074 measures 4.7V, and this is using the same cable and the same inline terminator. While the Siglent is very consistent between 1MHz and 120MHz, the Rigol goes from ~5V to 4.3V from 1MHz to 120MHz.

When you say that the response is not flat, you mean the response of the oscilloscope? I would expect a 350Mhz scope to be able to measure with some accuracy the amplitude of a 120Mhz sine wave, if not what should I do? Could it be a defective unit?
Yes the DSO frequency response.

If it were me I'd hit Default for each DSO to return it to known factory settings then use Autoset and then add Vp-p and Vmax measurements and compare results. Compare apples with apples.  ;)

Take the time to grab some screenshots to post here too.
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Offline TK

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #642 on: March 11, 2019, 12:24:00 am »
I assume you are using infinite persistence to show this?  I kind of noticed this with trigger levels below 1V previously, but as I was looking at digital signals - I assumed the noise was there.
No, I am using minimum persistence
 

Offline kahuna0k

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #643 on: March 11, 2019, 05:23:06 am »
Yes the DSO frequency response.

If it were me I'd hit Default for each DSO to return it to known factory settings then use Autoset and then add Vp-p and Vmax measurements and compare results. Compare apples with apples.  ;)

Take the time to grab some screenshots to post here too.

Switched to the coaxial that came with the SDG2042X and to a T plus 50Ohm terminator, got the same results:
 

Offline 2N3055

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #644 on: March 11, 2019, 05:54:27 am »
MSO5000 seems to have Gaussian response (constant slow rolloff) as opposed to Siglent flatter and sharper filter.
Bottom line is, scope bandwith is specified  at - 3dB which is 0.707 of baseline amplitude, meaning 3.53 V is cutoff frequency..
That means that within it's frequency range, Siglent will be more accurate in amplitude across it's bandwidth, but Rigol should have nicer step response. Each is better for some purposes..
 

Offline tautech

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #645 on: March 11, 2019, 06:41:12 am »
Yes the DSO frequency response.

If it were me I'd hit Default for each DSO to return it to known factory settings then use Autoset and then add Vp-p and Vmax measurements and compare results. Compare apples with apples.  ;)

Take the time to grab some screenshots to post here too.

Switched to the coaxial that came with the SDG2042X and to a T plus 50Ohm terminator, got the same results:
Interesting, thanks for grabbing those screenshots.
For the record please state the SDG p-p voltage setting, 5V I'm guessing.

Can I ask if you've done a Self Cal on all 3 instruments ?

Can you also check some DC measurement values ?
You can use the SDG to supply them. We'd be looking for similar inaccuracies and you can go back to 1 M ohm settings.
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Offline David Hess

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #646 on: March 11, 2019, 07:18:22 am »
David, old Rigols did RMS over highly decimated screen pixel data. That resulted in measurements being made over filtered /distorted data.

That is true of any DSO and any sampling RMS instrument.  Decimation does not alter the RMS value and instead increases the uncertainty.  This is easy enough to understand by considering what happens to the standard deviation of a set of data points when they are decimated; the standard deviation does not change but the uncertainty does.

Note that since decimation has no effect on the RMS value, aliasing does not either.  The noise depends on the bandwidth and not the sample rate.  The record length has a minor effect because low frequency noise components longer than the record length are not captured and some measurements take advantage of this to limit low frequency noise.

A DSO where the display record is a histogram like a DPO (digital phosphor oscilloscope) can also make an accurate RMS measurement of the display record.  So whatever Rigol is doing to produce a display record, it is not this.


Quote
What do you think, what would be proper protocol to verify that RMS works well this time?

When I did this test on my DSOs, I used one of my analog oscilloscopes to measure its own RMS noise using the tangential method and then I measured the same noise using the RMS function of my DSO.  They agreed to better than 5%.  I was alerted to the problem with Rigol's DSOs when someone posted a self noise measurement which was more than an order of magnitude too high and not consistent with the displayed noise.

In theory any Gaussian noise source can be used with a controlled measurement bandwidth however how do you calibrate the source?  I used the tangential measurement method with an analog oscilloscope for lack of anything better and that may be the most available method.  In theory a DSO can use this method but only if its display accurately duplicates the response of an analog display.  Most of the old Tektronix TDS series DSOs can do it as can an analog sampling oscilloscope but the display processing in newer DSOs prevents it.

My informal test when evaluating DSOs and I do not have a calibrated noise source handy is to just have the DSO measure its own front end noise but that only works because I know approximately what it should be and if it measures an order of magnitude or more high, I know the RMS function is broken.

Something is really messed-up with the front-end of the MSO5000.  I am using a 10KHz sinewave generated by the builtin AWG, BNC to crocodile, 10X Rigol probe.  In Normal acquisition mode, I cannot get a stable signal, it is triggering in both directions, rising and falling edge.  When I switch to average mode with 2 averages, the signal gets attenuated by more than 50%, then Hi-Res acquisition mode brings back the signal to full, but the double triggering disappears.  I use the same cable with the Rigol probe on my Keysight EDUX1002G and it works perfectly, as expected.

Can anyone try the same setup and verify?

I do not need to verify this as I know exactly what the problem is.  I think Dave even discusses and illustrates it in one of this videos but I know w2aew covered it; see the video below.

DDS/AWG outputs contain significant glitch energy from the quantized DAC steps which means any part of the waveform has high frequency rising and falling edges.  Depending on exactly how sensitive the trigger is and how it is implemented, the oscilloscope's trigger may see both edges.  This is much less of a problem with analog function generators which have a continuous (non-quantized) output but if their output is noisy enough, it can happen with them also.

For DSOs which implement an analog trigger path, the trigger coupling can sometimes be adjusted to prevent this.  For DSOs with a digital trigger path like the Rigol, trigger coupling depends on a digital filter and Rigol has had problems with this in the past.  Did they ever get AC trigger coupling working on their high end DSOs?  It was broken on the DS1000Z series for a long time.


« Last Edit: March 11, 2019, 07:20:16 am by David Hess »
 
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Offline kahuna0k

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #647 on: March 11, 2019, 08:23:06 pm »
Interesting, thanks for grabbing those screenshots.
For the record please state the SDG p-p voltage setting, 5V I'm guessing.

Can I ask if you've done a Self Cal on all 3 instruments ?

Can you also check some DC measurement values ?
You can use the SDG to supply them. We'd be looking for similar inaccuracies and you can go back to 1 M ohm settings.

Yes, all self calibrated and the SDG p-p voltage was 5V. Using DC I get good measurements from both the SDS1104X-E and the MSO5074.

I think that what 2N3055 said applies perfectly. The Siglent has a much flatter response in its bandwidth, but also falls down much faster, I'm unable to "measure" anything over 400Mhz on it, with the Rigol I'm able to "measure" up to 1Ghz, although, of course, this depends heavily on the sampling rate.
 

Offline tautech

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #648 on: March 11, 2019, 08:32:05 pm »
Interesting, thanks for grabbing those screenshots.
For the record please state the SDG p-p voltage setting, 5V I'm guessing.

Can I ask if you've done a Self Cal on all 3 instruments ?

Can you also check some DC measurement values ?
You can use the SDG to supply them. We'd be looking for similar inaccuracies and you can go back to 1 M ohm settings.

Yes, all self calibrated and the SDG p-p voltage was 5V. Using DC I get good measurements from both the SDS1104X-E and the MSO5074.

I think that what 2N3055 said applies perfectly. The Siglent has a much flatter response in its bandwidth, but also falls down much faster, I'm unable to "measure" anything over 400Mhz on it, with the Rigol I'm able to "measure" up to 1Ghz, although, of course, this depends heavily on the sampling rate.
Nor should you, it's just a 100/200 MHz 1 GSa/s DSO.
Best sampling rate available is just 1 GSa/s whereas how many times that is the sampling rate for the Rigol ?
No surprises there as the HW won't permit it. LOL.  :)
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Offline mroek

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #649 on: March 11, 2019, 09:12:04 pm »
Yes, all self calibrated and the SDG p-p voltage was 5V. Using DC I get good measurements from both the SDS1104X-E and the MSO5074.

I think that what 2N3055 said applies perfectly. The Siglent has a much flatter response in its bandwidth, but also falls down much faster, I'm unable to "measure" anything over 400Mhz on it, with the Rigol I'm able to "measure" up to 1Ghz, although, of course, this depends heavily on the sampling rate.
Nor should you, it's just a 100/200 MHz 1 GSa/s DSO.
Best sampling rate available is just 1 GSa/s whereas how many times that is the sampling rate for the Rigol ?
No surprises there as the HW won't permit it. LOL.  :)

But still, as long as the input signal is below Nyquist and has sufficient amplitude, you are able to detect the presence of the signal, and also approximate the frequency. I actually did this yesterday, when I wanted to know if a car key was actually transmitting a signal. The key uses a 433 MHz carrier, and I simply looped the ground clip to the probe tip, and held the key inside the loop and pressed the button. I could clearly see that the key was transmitting, and I could also "measure" the frequency, either with cursors or the FFT function. This will of course just give me a ballpark measurement, but I still found it interesting. And the purpose in this case was just to detect if the key worked or not, and for that the scope did the job ("unlocked" SDS1104X-E) perfectly.

 


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