Author Topic: Using (and living with) Siglent SDS1000X-E Series Oscilloscopes  (Read 13765 times)

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Online bdunham7

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Re: Using (and living with) Siglent SDS1000X-E Series Oscilloscopes
« Reply #25 on: June 30, 2021, 05:46:53 pm »
6. The scope can measure skew and offsets between channels, it just treats them separately e.g. scope is 2 + 2 channels.

The scope is 2+2 channels as far as its ADC architecture goes, but they should be aligned.  This would be a huge issue if you were looking at 4 logic channels, for example.  Did you contact Siglent?
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Offline SimonMTopic starter

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Re: Using (and living with) Siglent SDS1000X-E Series Oscilloscopes
« Reply #26 on: June 30, 2021, 06:07:11 pm »
6. The scope can measure skew and offsets between channels, it just treats them separately e.g. scope is 2 + 2 channels.

The scope is 2+2 channels as far as its ADC architecture goes, but they should be aligned.  This would be a huge issue if you were looking at 4 logic channels, for example.  Did you contact Siglent?
Agreed, they should be aligned and the spec for horizontal alignment is < 100ps across the scope (page 9 of the spec sheet). Agreed, it would be a huge issue for looking at anything that's 4 channel and would imply phase shifts that don't exist. It might also affect the decoding of a serial bus if the clock and data were split across channels 1 and 3.

As I get to know the scope, I'm starting to use channels 1 and 3 for dual channel use. This provides the full 1GSa/s sampling rate. If it's not aligned between the first and second pair of channels e.g. separate ADC chips, then the extra sampling can't be exploited. One of the reasons I bought the SDG1032X FG was the relative ease of evaluating bode plots. The outcome of this is to show frequency and phase shift, so I would like the measured phase to be accurate. I haven't tried it so far, but I would expect to use the best pair of channels e.g. 1 & 3, and not simply 1 & 2.

Simon
« Last Edit: July 02, 2021, 07:46:30 am by SimonM »
 

Offline rf-loop

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Re: Using (and living with) Siglent SDS1000X-E Series Oscilloscopes
« Reply #27 on: July 01, 2021, 07:24:18 am »
Channel skew is specified on P9 in the datasheet:
Channel Skew <100 ps
https://www.siglenteu.com/wp-content/uploads/dlm_uploads/2020/12/SDS1000X-E_DataSheet_DS0101E-E04C.pdf

Whenever you strike something that doesn't look right use Default to bring settings back to factory then run Self Cal and revisit the measurement.
For BNC connections an unmatched pair of cables can often produce different results.

Thanks.

I am returning the scope to the factory setup and running Self Cal before revisiting the measurements.

The BNC connections are with/without the 50-ohm termination. Results are unchanged.

The cables are pretty well matched - they are the 4x PP510 probes. Swapping the probes around, the results are unchanged.

Here is what I did to simplify the setup (one channel of FG directly connected via two probes to the scope)

I have removed the 50-ohm terminator and setting the FG to Hi-Z. The setup is about as simple as it can be.

There is a setting for Quick-Cal on the scope. I hadn’t noticed it before and it was switched ON. I switched it OFF because the condition of varying temperature doesn’t apply.

I have reset the scope as follows:

1. Reset to factory defaults;
2. Use the scope Self Cal calibrate operation (takes about 5 minutes);
3. Press default button;
4. Set all four probes to 10X;
5. Set all four channels to the same 2V/div, 0V offsets;

Without anything connected, the four channels are overlain at 0V.

Set the FG to 10MHz and Hi-Z. Channel 2 is off. There is no 50-ohm terminator.

1. Channel 1 is triggered and displays the waveform with a probe point directly off the FG;
2. Channel 2 is added and the probe is connected to the same FG output. Both channels are in phase;
3. Move the 2nd probe from channel 2 to channel 3. The scope is out of phase;
4. Move the 2nd probe from channel 3 to channel 4. The scope is out of phase;
5. Move the 2nd probe from channel 4 back to channel 1. The scope is in phase;

When the scope is in phase the 2nd trace covers the first trace, otherwise, they are out of phase.

I can manually skew a second channel to overlay the first trace. -29.35ns is required.

NB without the 50-ohm terminator the results are as before, there is one difference that is expected: displayed trace doubles (Vp-p) because there is a change in the load impedance when connecting/disconnecting a second probe.

At 1MHz and probes set to 1X, timebase altered and scope input channels set to 1X, 2V/div, 0V offsets, it shows the same waveform.

Adding the second channel, overlays in phase, moving 2nd probe to channel 3 and then to channel 4 also shows the channels out of phase.

At 1MHz the amount of phase shift on the screen is reduced e.g. to 1/10. Skew to correct this is again best at -29.35ns.

Switching between probes doesn’t vary/alter the result.

Observations and conclusions

1. Removing the 50-ohm terminator doesn’t vary the out of phase outcome;
2. Varying which probes are used doesn’t vary the outcome;
3. Changing frequency e.g. between 10MHz and 1MHz and using probes 1X doesn’t vary the outcome;
4. The scope doesn’t show phase alignment between channels (1 & 2) with channels (3 & 4) after calibration;
5. The scope is remarkably aligned within the channels (1 & 2) or channels (3 & 4);
6. The scope can measure skew and offsets between channels, it just treats them separately e.g. scope is 2 + 2 channels.

rf_loop provided a review of the scope and his analysis of skew indicated a very high degree of alignment (see page 76):

(Attachment Link)

NB the only mismatch is with attenuation (might be expected) and not with skew - each channel is very well aligned.

Simon

Not me. I think it was @Performa01

I do not remember/know with most new FW if there is still total deep reset.
During whole power up boot time  toggling very fast Math button. If it works you know it because you can see it have also reset calibration. If not work first time try again... As far as I remember factory reset (via menu) do not deep reset so that also all cal data is reset. (@tautech can perhaps confirm if this method is still there today)

And of course then calibration and -nothing- must be connected to input BNC's. Nothing - it really mean nothing. (how it affect it also depends scope model, in some old model whole internal cal signal come to BNC centers but do not know SDS1004X-E, I do not have this model available here for tests, these are in my homeland, not here in China)

Now if I understand right you have skev betwee (Ch1/Ch2 pair, (ADC1)) and (Ch3/Ch4 pair (ADC2))  roughly near 30ps.  Ande this is really lot of. Example 6 meter  RG316/U  have roughly 29ns travel time.


There is very poor simple and dirty method. "Wilderness and desert method. Just for bullet proof verify the problem is or is not."
ETA After seen your video:
Yoy can Connect your BNC T to channel 2 and trigger to CH2. Connect just one your coaxial from SDG to this T other side. Then take just very short copper wire and connect it from BNC T other side center as short as possible to CH3 input center. Now you have only one coax from SDG and very small, and roughly known,  signal travel time difference between CH 2 and Ch3 input.  Just 1kHz is signal where is fast edge is enough (square, pulse or 0% triangle). With this, because you do not have better things (special time matched cables and good splitter etc) available, you can infinitely proof if there is error between channels (when they are different ADC).

« Last Edit: July 03, 2021, 09:12:31 am by rf-loop »
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Online tautech

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Re: Using (and living with) Siglent SDS1000X-E Series Oscilloscopes
« Reply #28 on: July 01, 2021, 08:21:49 am »
I do not remember/know with most new FW if there is still total deep reset.
During whole power up boot time  toggling very fast Math button. If it works you know it because you can see it have also reset calibration. If not work first time try again... As far as I remember factory reset (via menu) do not deep reset so that also all cal data is reset. (@tautech can perhaps confirm if this method is still there today)
Those are enough as we should not share the other dealer secret Reset's we have.  ;)
However there still is Secure Erase in the Save/Recall menu used for deleting User settings such as LAN/WiFi and Reference waveforms.

Quote
If with this desert method there still is 10's of ns difference, if even ns difference, it is clear your scope have some severe problem what need Siglent service.
Soon to unpack my old prerelease SN#12 SDS1104X-E and check for channel skew and will post screenshots......

Channel skew tests.
Source SDG6202X square wave terminated with Tek feedthrough to Tee and to scope inputs with Siglent 1 GHz rated 1m BNC cables.
Dot and Vector displays.
« Last Edit: July 01, 2021, 08:50:50 am by tautech »
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Offline SimonMTopic starter

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Re: Using (and living with) Siglent SDS1000X-E Series Oscilloscopes
« Reply #29 on: July 01, 2021, 08:19:36 pm »
Those are enough as we should not share the other dealer secret Reset's we have.  ;)
However, there still is a Secure Erase in the Save/Recall menu used for deleting User settings such as LAN/WiFi and Reference waveforms.

Thanks, I have used "Secure Erase" that removes user settings and the "Hard Reset" documented here: https://siglentna.com/operating-tip/oscilloscope-hardware-reset/. "Secure Erase" is suggested to remove the user settings e.g. if you were about to sell the scope. The "Hard Reset" is recommended for issues with start-up and whilst it certainly delays the bootup, it doesn't affect the ~ 30ns skew between pairs of channels (separate ADCs).

I sent a follow-up video (using DropBox) to my Siglent dealer showing the setup of the FG and channels on the scope:

https://www.dropbox.com/s/lv0rczm5bcguz9k/IMG_1965.MOV?dl=0

The movie shows all channels show deskew 0. At 1MHz the two traces separate (widen) using input channel 1 and moving 2 -> 3 or 2 -> 4. At 15 MHz the out of phase is obvious as input is moved across to 3 or 4. Emailed the dealer screen prints. With timebase set up for 15MHz sine wave, the 1MHz or 15MHz traces show a shift of 1 division when 2nd ADC is used. Ideally, this wouldn't need to be manually corrected by remembering to set a deskew of ~ -30ns on channels 3 & 4. Hopefully, there is an easy re-calibrate fix, or I (aka the 'rookie') overlooked something.  ;)

Simon
« Last Edit: July 04, 2021, 10:58:30 pm by SimonM »
 

Offline SimonMTopic starter

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Re: Using (and living with) Siglent SDS1000X-E Series Oscilloscopes
« Reply #30 on: July 04, 2021, 11:24:25 pm »
The more I look at my scope, the less confident I think I know anything about what it's doing...

I have two cables, one was delivered as RG58 50 ohm and the second is RG59 75 ohm. I bought the RG59 that was described as RG58 - when it arrived, I noticed a difference and checked the identification printed on the cable. The vendor had made a mistake because it is RG 59! I am looking to replace both BNC cables with some better and balanced RG58 50-ohm cables, as buy cheap, buy twice...

I'm looking at the differences using a 15MHz square wave out of SDG1032X set for 50 ohms) on both channels with 2nd channel locked, feeding 50-ohm terminators into the scope. I'm using channels 1 & 3 of the scope and the waveforms are slightly different, with RG58 providing a squarer waveform, especially evident at 30MHz, compared to the RG59.

Both these channels should be in phase - that's a known problem with the scope that the dealer is looking into and using channels 1 & 2 they can be shown to be in phase. Here's a print, where they are out of phase using channels 1 & 3:

1233548-0

As well as being out of phase, I get an interesting effect when I turn on either of the two other channels. The 3rd channel is phase-shifted, see the attached print. At 30MHz this is also particularly noticed, but for the cables, I was using a lower frequency signal.

1233550-1

Channels 2 & 4 aren't connected to anything. Since I'm triggering on channel 1, this stays exactly centred around the trigger point, but channel 3 moves back. Unless I haven't thought it through, I wouldn't expect adding another channel to the display, to make any difference to existing channels. Perhaps it just highlights again that the 2nd ADC isn't (particularly) aligned with anything? I get a similar shift if I trigger on another channel and add either of the other two channels.

Simon

 

Offline StillTrying

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Re: Using (and living with) Siglent SDS1000X-E Series Oscilloscopes
« Reply #31 on: July 05, 2021, 11:54:42 pm »
It shouldn't do that either.

"that's a known problem with the scope that the dealer is looking into"

Have they told you anything such as tested one of their current stock? The scope's own 120ns rise time 1kHz would be enough to see the 29ns error.

All I can think of is reinstall the latest firmware, hopefully tautech will know if that's a worth trying not.

I suspect it will be going back myself.
.  That took much longer than I thought it would.
 

Online tautech

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Re: Using (and living with) Siglent SDS1000X-E Series Oscilloscopes
« Reply #32 on: July 06, 2021, 02:16:04 am »
It shouldn't do that either.

"that's a known problem with the scope that the dealer is looking into"

Have they told you anything such as tested one of their current stock? The scope's own 120ns rise time 1kHz would be enough to see the 29ns error.

All I can think of is reinstall the latest firmware, hopefully tautech will know if that's a worth trying not.

I suspect it will be going back myself.
Yeah I know......been busy....

Problem is most likely with settings in SDG1032X where outputs are not perfectly edge aligned by default so settings must be tweaked to ensure edges are perfectly in phase.

Adjust as follows:
SDG>Utility>P2>Phase Mode = Locked
Utility>P1>Channel Copy Coupling>Track = ON

This SDG1032X requires a Ch2-Ch1 Phase Deviation of -2o

Screenshots below SDS1104X-E where SDG Ch1 always = Ch4 on SDS.
First 2 on each scope ADC and last 2 on same ADC.
The scope is NOT the problem only the phase deviation in the SDG.
It should also be noted that once channel phase differences have been trimmed out that a Power ON =Last setting be made so adjustments to phase differences will be saved.
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Online bdunham7

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Re: Using (and living with) Siglent SDS1000X-E Series Oscilloscopes
« Reply #33 on: July 06, 2021, 02:25:20 am »
The scope is NOT the problem only the phase deviation in the SDG.

I'm not clear on what you are saying here...

At one point he split a single channel and observed 29ns of difference on the scope.  How could the scope not be the problem?
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

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Re: Using (and living with) Siglent SDS1000X-E Series Oscilloscopes
« Reply #34 on: July 06, 2021, 03:03:46 am »
The scope is NOT the problem only the phase deviation in the SDG.

I'm not clear on what you are saying here...

At one point he split a single channel and observed 29ns of difference on the scope.  How could the scope not be the problem?
Where, which post ?
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Online bdunham7

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Re: Using (and living with) Siglent SDS1000X-E Series Oscilloscopes
« Reply #35 on: July 06, 2021, 03:14:18 am »
Read my post #16 and his reply #17.  If he did what he said he did--both probes to one channel, switching the connections at the scope and observing no change or reversal of the phase shift--that scope is borked.

I have no idea what could possibly be going on with that scope, but something isn't right.  29ns is huge for any physical delay and the only thing I can think of is that there is a factory-only calibration constant (or at least not done during self-cal) that has a range greater than necessary and that value has accidentally been set to the min or max somehow.
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Online tautech

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Re: Using (and living with) Siglent SDS1000X-E Series Oscilloscopes
« Reply #36 on: July 06, 2021, 03:26:29 am »
Read my post #16 and his reply #17.  If he did what he said he did--both probes to one channel, switching the connections at the scope and observing no change or reversal of the phase shift--that scope is borked.

I have no idea what could possibly be going on with that scope, but something isn't right.  29ns is huge for any physical delay and the only thing I can think of is that there is a factory-only calibration constant (or at least not done during self-cal) that has a range greater than necessary and that value has accidentally been set to the min or max somehow.
You may be correct but I'm not convinced as yet.
SimonM needs to do a factory reset on his AWG so to eliminate any possibility the SDG1032X is not the source of phase difference.
His last screenshots show ~180o phase difference @ 15 MHz and there's no way it should be that far out.
I believe something has been overlooked.
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Offline StillTrying

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Re: Using (and living with) Siglent SDS1000X-E Series Oscilloscopes
« Reply #37 on: July 06, 2021, 03:35:06 am »
Yeah I know......been busy....

I/we mean SimonM's dealer in the UK.

Definitely the scope, first 2 images in Reply#13

https://www.eevblog.com/forum/testgear/using-(and-living-with)-siglent-sds1000x-e-series-oscilloscopes/msg3597615/#msg3597615

CH2 overwrites CH1, but CH3 doesn't overwrite CH1

"His last screenshots show ~180o phase difference @ 15 MHz and there's no way it should be that far out"

1/15M = 66.6ns, half a cycle is 33ns which is the 29ns error, getting close to 180 deg for 15MHz.
.  That took much longer than I thought it would.
 

Online bdunham7

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Re: Using (and living with) Siglent SDS1000X-E Series Oscilloscopes
« Reply #38 on: July 06, 2021, 03:39:10 am »
SimonM needs to do a factory reset on his AWG so to eliminate any possibility the SDG1032X is not the source of phase difference.
His last screenshots show ~180o phase difference @ 15 MHz and there's no way it should be that far out.

How could the SDG be the issue if he only used  one channel??

The phase difference just seems to be about the same 29ns lag in the 3/4 ADC, although it seems to reduce a bit at 500MSa/s. 

Quote
I believe something has been overlooked.

It certainly seems like something that you eventually figure out and slap yourself in the head, "DOH!" and wonder what you were thinking.  I just can't think of any user setting that would cause this.
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Offline StillTrying

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Re: Using (and living with) Siglent SDS1000X-E Series Oscilloscopes
« Reply #39 on: July 06, 2021, 03:48:15 am »
It certainly seems like something that you eventually figure out and slap yourself in the head, "DOH!" and wonder what you were thinking.  I just can't think of any user setting that would cause this.

I had to read Reply#13 3 times the first time, and now again so 4 times.

"29ns is huge for any physical delay"

I could imagine the PCB needs a fixed 29ps delay somewhere and the firmware is using ns instead. :)
.  That took much longer than I thought it would.
 

Offline Orange

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Re: Using (and living with) Siglent SDS1000X-E Series Oscilloscopes
« Reply #40 on: July 06, 2021, 05:19:49 pm »
There have been other reports of phase error's with this scope. see for instance this posting

https://www.eevblog.com/forum/testgear/siglent-sds1204x-e-released-for-domestic-markets-in-china/msg3233194/#msg3233194

Forget about all the noise of the SDS generator or wrong cabeling or Bode plot crap... It's the scope

I suspect that this is an error in the FW or in the calibration process, which needs to correct the timing of the 2 ADCs

You can actually watch the process on screen if you put the scope into single shot mode.
setup:
TB at 50ns/div. Generator at 10MHz, maximum sample memory (14 meg), sinx/x interpolation, vector mode.
sequence:
First only enable channel 1.
single shot, one channel visible.
enable channel 3.
now watch carefully what happens if you do a single shot.
you first see a misalignment of two sines, and immediately, a time shift on channel 3, aligning channel 1 and 3

I have witnessed this error myself with older FW. Now with the latest FW, the error has been reduced to 600 ps
Still not 100% ok, and certainly not within the Siglent spec of 100 ps

What version of FW on the scope are you using SimonM ?
 

Offline rf-loop

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Re: Using (and living with) Siglent SDS1000X-E Series Oscilloscopes
« Reply #41 on: July 07, 2021, 06:12:19 am »
Very simple and robust method for check and measure this level of oscilloscopes channels time difference.
For avoid all hassle and suspects use ONLY one signal. Take this same signal with Time matched cables to scope channels under test. You do also not need play with different frequencies etc or Phase angles. Just measure time, repeat, measure time.
Simple method is Y cable. Yes, just cables centers connected and shields connected. Do not think impedance matching here, this is simple split. Now it  is also easy to fine adjust both output sides perfect time if want.

Third cable in this Y, input. This length do not matter, 1cm  to 1 meter is just ok.

Connect it to gen out and then these Y cable time mached sides to scope channels under test.
Use what ever signal what give fast edge as possible. It can be pulse, square, triangle0% or even sine but twith sine you need high frequency. Using just fast edge waveforms you can use 1kHz or 1MHz, no matter... but keep this base freq so that period is least well over 2 times max time difference in channels under test... so even first time noob can not go to wrong.

Also I have seen many og SDS1000X-E scopes, 2 and 4 channels. I have never ever seen 10 or 30ns time skew between any channel. Also I ask how it can be FW problem if there 1000 scope without this problem and 1 scope with this problems. Just wake up and  start  thinking...

Also it is amazing what kind of hassle this looks when this is tested in this thread...  how it can be this kind of total hassle.

Even if can not have/diy this kind of Y cable... I have told to OP how he can make very very easy and robust test just with all  what he have... but no... just continuing this hassle like walking in circle where nothing is clear at once.

Here attached one image.
There is also simpliest possible DIY Y cable.
Done so that cable time skew is roughly 2.5ps so I just multiply it with 2 so that I can always trust it is <5ps when BNC are connected perfectly. I have hand adjusted lengths using scope when connect this Y center.
Note that RG316/U  travel time 4.856ps/mm (ref. Belden)  (yes I did many iterations for get as perfect match what I can easy detect with my tools. Note that 1cm difference mean still under 50ps error, so you can do this kind of cable just measuring length)
With this kind of simple split it is very important that cable outputs load impedance/reactance are as equal as possible. Still naturally it is not at all impedance matched signal transmission. But, this do not matter because only important is  Time difference and just roughly.

No need hassle with 100MHz or 1MHz or 15MHz. Just what ever from 1s to  1us period edge is enough and measure channels time skev (including amount of Y cable time error).  Do not play with probes or other things what can way or other suspect. Just reduce all unknowns to minimum.

If scope have roughly 29ns enormous time skew between channel pairs (different ADC), as previously told, no need anything but return it as DOA and get it changed or repaired. Have you contacted Siglent technical support.
This kind of thing need just one or two very simple and easy measure and thats all. Result is failed or ok. Until start playing "this and that".

« Last Edit: July 08, 2021, 04:03:09 am by rf-loop »
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Offline StillTrying

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Re: Using (and living with) Siglent SDS1000X-E Series Oscilloscopes
« Reply #42 on: July 09, 2021, 02:48:17 pm »
Has your replacement SDS1104X-E arrived yet. :)
.  That took much longer than I thought it would.
 

Offline MathWizard

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Re: Using (and living with) Siglent SDS1000X-E Series Oscilloscopes
« Reply #43 on: July 09, 2021, 09:48:21 pm »
Why is it sometimes a horizontal line is shown as you set the trigger level, and other times, it won't show it ? I haven't noticed a pattern to why it stop's working, I guess some software bug

I am very pleased tho with my siglent equipment in general so far. I'd like to try their handheld Oscope/DMM, if only I had a need to take 1 on a roadtrip repair.
 

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Re: Using (and living with) Siglent SDS1000X-E Series Oscilloscopes
« Reply #44 on: July 10, 2021, 01:40:46 am »
Why is it sometimes a horizontal line is shown as you set the trigger level, and other times, it won't show it ? I haven't noticed a pattern to why it stop's working, I guess some software bug
Level lines only show when adjustments are made and for a short period afterwards and then only the level marker is displayed as reference to the newly set level.

Quote
I am very pleased tho with my siglent equipment in general so far. I'd like to try their handheld Oscope/DMM, if only I had a need to take 1 on a roadtrip repair.
If you can wait there’s a new SHS series coming......dunno much more sorry other than they will have a new GUI and be more aligned to the later X and X-E model DSO’s.
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Offline skempf

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Re: Using (and living with) Siglent SDS1000X-E Series Oscilloscopes
« Reply #45 on: July 13, 2021, 12:12:35 pm »
Is there a summary checklist of all the (non trivial) items you should check or test when unboxing a new scope? (I just got a hold of an 1104x-e).
 

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Re: Using (and living with) Siglent SDS1000X-E Series Oscilloscopes
« Reply #46 on: July 13, 2021, 12:26:43 pm »
Is there a summary checklist of all the (non trivial) items you should check or test when unboxing a new scope? (I just got a hold of an 1104x-e).
Not really.
In the process of compensating the probes check each probes 1x/10x switch for clean and correct attenuation of the probe compensation output.....very occasionally there have been dud probes in the past....of late, rare.
Set all probes and channel attenuation to 10x.
You may find the button beeps sound annoying so disable it in Utility>Sound.
Do all that ^ then reboot.

Then enjoy.  :)
« Last Edit: July 13, 2021, 12:29:07 pm by tautech »
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Offline SimonMTopic starter

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Re: Using (and living with) Siglent SDS1000X-E Series Oscilloscopes
« Reply #47 on: July 14, 2021, 10:20:21 am »
Code: [Select]
Has your replacement SDS1104X-E arrived yet. :)

Yes - the UK dealer replaced the scope with a new one from their current stock
The new scope has the same (current) firmware, was manufactured (calibrated) earlier this year, and has a serial number that indicates it is from the same batch (the dealer had 38 in stock).

No noticeable skew between channels
(ADC 1 = channel 1 & 2) and (ADC 2 = channel 3 & 4) have no noticeable skew that I could detect.

I'm using:
  • SDG1032X Function Generator with one output at 30MHz square wave (50-ohm output) on channel 1 (channel 2 is OFF)
  • T Splitter and two (near identical) 1m BNC cables
  • 50Ω Impedance Adapter on each of the two scope inputs
I have let the scope warm-up, calibrated with "Self Cal" whilst all probes and BNC cables are unconnected, and then restarted the scope.

I'm using the fastest square wave source I have and the fastest rise time available. With the impedance adapters, the signal is very clean.

My tests - confirm all is OK
On all the channels (triggered + 2nd): 1 + 2, 1 + 3, 1 + 4, 2 + 1, 2 + 3, 2 + 4, 3 + 1, 3 + 2, 3 + 4, etc.

I can observe the traces being in phase and the measured skew averages 20ps across all combinations.

I have added the extra channels, hidden them, and repeated all the combinations I could think of without any issues. I'm manually triggering and getting readings of 10ps, 20ps, or 30ps using the measured skew channel A and channel B. The Siglent dealer had previously set up the scope and triggered it with a 60MHz sine wave with the triggering and measurement of skew for channels 1 & 3 still active when I received it. Initially, the scope showed two power cycles.

Conclusion
I don't have access to the same level of test equipment as my Siglent dealer. I'm getting a good result using the fastest rise time available using my own function generator. Any variations measured by the scope are more than likely an indication of small differences between the BNC cables, which are acting as a filter on the output signal from the FG.

I'm pleased with the outcome and delighted with my Siglent scope and also my function generator.

Simon
« Last Edit: July 14, 2021, 12:57:46 pm by SimonM »
 
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Offline Orange

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Re: Using (and living with) Siglent SDS1000X-E Series Oscilloscopes
« Reply #48 on: July 14, 2021, 12:06:56 pm »
Has your replacement SDS1104X-E arrived yet. :)

Yes - the UK dealer replaced the scope with a new one from their current stock
The new scope has the same (current) firmware, was manufactured (calibrated) earlier this year, and has a serial number that indicates it is from the same batch (the dealer had 38 in stock).

No noticeable skew between channels
(ADC 1 = channel 1 & 2) and (ADC 2 = channel 3 & 4) have no noticeable skew that I could detect.

I'm using:
  • SDG1032X Function Generator with one output at 30MHz square wave (50-ohm output) on channel 1 (channel 2 is OFF)
  • T Splitter and two (near identical) 1m BNC cables
  • 50Ω Impedance Adapter on each of the two scope inputs
I have let the scope warm-up, calibrated with "Self Cal" whilst all probes and BNC cables are unconnected, and then restarted the scope.

I'm using the fastest square wave source I have and the fastest rise time available. With the impedance adapters, the signal is very clean.

My tests - confirm all is OK
On all the channels (triggered + 2nd): 1 + 2, 1 + 3, 1 + 4, 2 + 1, 2 + 3, 2 + 4, 3 + 1, 3 + 2, 3 + 4, etc.

I can observe the traces being in phase and the measured skew averages 20ps across all combinations.

I have added the extra channels, hidden them, and repeated all the combinations I could think of without any issues. I'm manually triggering and getting readings of 10ps, 20ps, or 30ps using the measured skew channel A and channel B. The Siglent dealer had previously set up the scope and triggered it with a 60MHz sine wave with the triggering and measurement of skew for channels 1 & 3 still active when I received it. Initially, the scope showed two power cycles.

Conclusion
I don't have access to the same level of test equipment as my Siglent dealer. I'm getting a good result using the fastest rise time available using my own function generator. Any variations measured by the scope are more than likely an indication of small differences between the BNC cables, which are acting as a filter on the output signal from the FG.

I'm pleased with the outcome and delighted with My Siglent scope and also my function generator.

Simon

So you got it sorted, good to hear.

After all I was right that the scope was the problem.

From rf-loop:
Also I have seen many og SDS1000X-E scopes, 2 and 4 channels. I have never ever seen 10 or 30ns time skew between any channel. Also I ask how it can be FW problem if there 1000 scope without this problem and 1 scope with this problems. Just wake up and  start  thinking...
;)
« Last Edit: July 14, 2021, 12:10:18 pm by Orange »
 

Offline SimonMTopic starter

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Re: Using (and living with) Siglent SDS1000X-E Series Oscilloscopes
« Reply #49 on: July 14, 2021, 02:12:28 pm »
I do not remember/know with most new FW if there is still a total deep reset.
During the whole power-up boot time, toggling very fast Math button.

Yes, I had previously followed the instructions for the Oscilloscope Hardware Reset that are on the EU Siglent website. I also had an email from Siglent in Germany to confirm that a Hardware Reset "sorted" the problem until powering off (it didn't make any difference to the ~29ns skew, except delaying the startup and afterward, suggest a "Self Cal").

There is a very poor simple and dirty method. "Wilderness and desert method. Just for bulletproof verify the problem is or is not."

ETA After saw your video:
You can Connect your BNC T to channel 2 and trigger to CH2. Connect just one of your coaxial from SDG to this T other side. Then take just a very short copper wire and connect it from BNC T other side center as short as possible to the CH3 input center.

Now you have only one coax from SDG and very small, and roughly known, the signal travel time difference between CH 2 and Ch3 input.

With this, because you do not have better things (special time matched cables and good splitter etc) available, you can infinitely prove if there is an error between channels (when they are different ADC).

I appreciate the thought. As you say, we don't all have (so far) all the right test gear. On the new SDS1104X-E scope, I used one BNC cable, with a T splitter and two short lengths of copper hook-up wire. I'm putting the FG output (1 MHz square wave) into channels 1 & 3 and using channel 2 as a ground (see the picture).



The result of using it is also shown and the error is ~-5ps.



The scope traces are intertwined/overlain which is also a good sign.  :-+

Simon



PS one "useful" feature of the scope: after it has triggered, many of the measurements can be determined afterward e.g. I realized that the skew was not measured from the triggered channel (easily corrected) and I added some other useful info e.g. the Pk=Pk voltage and the rise time of the square wave. In the second scope picture, it's the exact same waveform with only the measurements updated.
« Last Edit: July 14, 2021, 02:47:01 pm by SimonM »
 


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