Using (and living with) Siglent SDS1000X-E Series Oscilloscopes

[SimonM]

Another new topic? I think it is good to separate out different topics so that we don't go too much off-topic.

This is about using (not buying, choosing, or comparing the SDS1000X-E Series Oscilloscope with other scopes).

It is about owning and living with a Siglent Scope for Home/Hobby/Enthusiast (HHE) Users e.g. someone who isn't necessarily owning/using the scope to derive their income. Other scopes are available^TM...

If most HHE OWners/Users are like me, they will evaluate their needs and buy only one of the scopes based upon how they want to use it. I would be the first to admit that I sometimes overestimate my needs and I'm fine with that - so I don't need to be reminded that I perhaps "got it wrong" and could have gone in a different direction by buying several pieces of equipment and "saving money". That's not to say that I'm not interested in how it goes with one of the other scopes in the series or how to do things in different ways. Because they are different and I can't afford to just buy them all, I am very interested in knowing more about all the scopes in the series that can be used (owned and lived with) and how they differ slightly, although I suspect that they are more similar than different.

The version I have is the SDS1000X-E 4-channel, 100MHz, Dual 1 GSa/s, Quad 500 Ms/s scope. Other versions have variations on this, with fewer channels or higher bandwidth, and these are the first (entry) series of digital oscilloscopes from Siglent. I'm not starting this topic because I have an issue with the scope and I don't have buyer's remorse. My impression is that Siglent does a nice job and creates an excellent piece of kit that will be very useful.

With the scope, you also get four 100MHz probes, the UK distributor includes a UK power cord and there is also a European cord in the box. There is a simple Quick Start Guide and on the web other resources available e.g. https://www.siglenteu.com/resources and https://www.siglenteu.com/service-and-support/ . The manufacturer's production (certification) date is from a few months ago and not surprisingly it has the latest firmware already installed. The products were initially released about three years ago and more recent versions have been released including the newer SDS1000X-U. I like the fact that the Firmware also has Release Notes, so you can decide if an update is really required and also learn about additional features they added. For my series of scope, there are 15 versions of Firmware (current and historical) but closer inspection shows that there are the current and four previous versions for this 4-channel version. There is also one version of the Operating System separately downloadable. The Firmware for the 2-channel was separated out and there is also Firmware for some of the Series' optional extras. As a "newbie" I don't want too much choice, but I do like to see the history, so what's there (in one place) is OK (good).

The main downloadable resources are a User Manual covering 1000X-E and 1000X-U and a Service Manual covering the 2-channel and 4-channel scopes. There is also a Programming Guide and some software which I haven't looked at. Being a bit "nerdy" I read the spec sheet in conjunction with the downloadable User Manual and the Service Manual before deciding to buy the scope. If you aren't "nerdy" then there is no need to look at the Service Manual but it has the advantage of letting you "look inside" without needing to remove the cover - mine had a holographic sticker that prevents prodding around! at first glance, the scopes all look similar but the position of the I/O in the User Manual hints at differences and the Service Manual shows that the layouts are a bit different e.g. placement of the PSU, the fan, and the mainboard being horizontal (2-channel) or vertical (4-channel).

Setting up the scope means plugging it in, attaching the four probes, and calibrating the probes to the scope. each probe comes with light-colored markers for the BNC and the probe to match the yellow, magenta, green, and blue controls, and display trace color. I calibrated the four probes after the unit was powered up with each probe attached and with the colored bands swapped on three of the probes (it may not matter) and with 10X selected on probe and scope. Worth noting is that the 4-channels are matched with four identical probes, so there is no immediate need to go out and (be compelled to) buy additional "stuff", at least when starting out.

Scope Calibration
The scope calibration is something that makes sense to do after the scope has reached a stable operating temperature and before the probe calibration is finalized. It isn't something to do last minute and the whole procedure is time-consuming. It's not simply a "press the button" and wait two minutes. It does a good job of calibrating, although it takes some time - best get a coffee or something.

Probe Calibration
The calibration waveforms to me look either square (when correctly setup) or needing adjustment with overshoot/undershoot (as supplied) that is symmetrical e.g. needing the same correction for the top or bottom. The "nerdy" part of me says this needs to be "spot on", so careful adjustment and close inspection (this might not be absolutely essential). I used the Auto Setup for each probe in turn and adjusted the Horizontal Timebase to show one cycle and a bit. Pressing the Channel button brings up soft menus above the horizontal buttons with the option to set the scope to 10X but also to invert the waveform. It may be obvious, but inverting the waveform also means that the Vertical adjustment can be used to zoom in and for the bottom of the waveform to remain in the same position. Put simply, there is no need to reposition the trace vertically. If all the channels are active, each channel overlays the previous one, which might be confusing, and "zooming in" is possible because there is no detectable DC offset. 

Attention - read what is on the screen
It may sound obvious, but it is worth reading what is displayed on the screen. An example is using the Utility Menu to check the Firmware level. When it says:

Press the "Single" button to exit

That is exactly what it means. Pressing buttons and rotary controls have no effect until you do press the "Single" button that is with the Trigger Controls on the RHS. Pressing any other button isn't the same! So, the scope hasn't "locked up" and there is no need to cycle the power button unnecessarily. Pressing and holding a button in for two seconds will bring up the Help. It's still a good idea to read the manual e.g. to know that this Help "feature" exists, but this helps too...

With audible feedback (or not)
Perhaps one of the first tasks on getting a new scope is to decide if the "audible" beep is something you want. I decided I could do without it. Putting the scope back to "defaults" can be changed as well. The scope can be restored to "defaults' which can be controlled by the User and there is also a factory default as well.  Because I want to return to "my default", I have the sound turned off and all four channels identically setup, 10X scope/probe, non-inverted DC - that's what made sense to me.

There have been previous topics for this family of scopes, so a lot has been said about it in the past and no need to repeat all that. For a new user, I thought it has some value to look at what you get today when starting out. FWIW, I'm a "newbie" to DSOs. So that's it for now.

Simon

[SimonM]

This is about using (not buying, choosing, or comparing the SDS1000X-E Series Oscilloscope with other scopes).

It is about owning and living with a Siglent Scope for Home/Hobby/Enthusiast (HHE) Users e.g. someone who isn't necessarily owning/using the scope to derive their income. Other scopes are available^TM...

USB ports (front) and (back)
It's the advancing years - I may be getting a bit slow (and gray-haired), but...

My 4-channel SDS1104X-E scope has two USB ports (for memory sticks) one on the front and also one on the back. The internals (according to the Service Manual at least) have internal shielding that will (probably) affect the WiFi direction/range if I plug the (EEVblog suggested TL-WN725N) dongle into the rear USB port. It had me thinking that, although the two USB ports are intended to be used for a USB stick (front) and WiFi dongle (back), they are probably the same and are "interchangeable".

Whilst it makes sense to put the USB stick in the front so that it can be easily removed to take to a computer, for me it makes more sense to keep a USB stick in the back. So that it's always "ready" and I haven't got to search for one. Normal operation is to transfer info back to the computer... I have a small USB stick that is a similar size to the Siglent Wifi dongle, so I doubt the airflow from the fan is altered by switching the use around. So now, when I have something interesting to record, I don't have to hunt down a FAT32 formatted stick - because it's already with the scope. With some of the longer USB sticks, I know that having one in the front will someday be a mechanical (leverage) issue, and being "tucked away" around the corner helps.

LAN cable
I do have a 25' long LAN cable and I wanted to connect the scope (in one room) to my fixed computer (in another room across a hallway) using the cable. Whilst it works, I'm mindful that it's not exactly HSE compliant and the last thing I want is for someone else to nudge the scope or computer onto the floor (or trip up, btw). There may be arguments for using a LAN cable and not WiFi but for this, it makes sense to at least try the WiFi option before it's a trip hazard. If finding a small USB stick is a problem, trying to remember where a WiFi dongle is (they seem designed to be lost), means that I ordered a 2nd (inexpensive) TL-WN725N from Amazon.

Operation with a PC
I have an iMac for normal use and a dedicated laptop with Windows for another use. I don't like to mix the two. I will be using the Windows software for the scope and I use VMWare Fusion to run Windows Applications alongside Mac Apps. That's one of the things on my list to try and experience says it should work just as well on the Mac. Having access to the machine remotely via a web browser is a "neat trick" because it's not operating system dependent, but for using the scope, the Windows S/W seems to be essential. Overall, the scope greatly exceeds my needs and works great!

Simon

[tautech]

Random bits reply......

Installing options generated online by whatever means is so much easier when the scope is connected to a PC of any flavor if instead of EasyScopeX you use the inbuilt webserver. Copy/Paste> Enter, yes it's that simple !

To configure the scope for the webserver unless you know your LAN IP you need turn ON DCHP and let your modem assign an IP for the scope to use or better still have a known block of IP addresses reserved for instruments maybe even on their own subnet.
When LAN or a WiFi connection is enabled just enter the scopes IP into your PC browser and if all is well you will arrive at the scopes Welcome page where you can select Info, Instrument control and SCPI pages.
All that can be done in the scopes menus or front panel control can also be done remotely from the Instrument control page using the webserver.

USB A sockets
While these scopes have a very welcome 2 A type sockets sadly that's not enough at times to power the likes of USB drives, STB3, active probes, deskew fixtures and the SAG1021I AWG so some juggling does happen.
USB sticks, WiFi dongle and SAG1021I all must be plugged directly into the scope whereas other devices can be powered from any USB supply.

[SimonM]

Installing options generated online by whatever means is so much easier when the scope is connected to a PC of any flavor if instead of EasyScopeX you use the inbuilt webserver. Copy/Paste> Enter, yes it's that simple!

Instrument Control isn't simply READ ONLY
Thanks, it's a big help to know that the webserver should be interactive and that the Instrument Control isn't simply READ ONLY !!! (User Error).

I did try EasyScopeX - having installed the Visa runtime and Windows .net prerequisites. I did get it to briefly display a picture of the scope (the rotary controls are round) but it's certainly NOT easy. It takes control of the scope (locking it) and it can lose the link (forever). There may be occasions where EasyScopeX is a good thing - but I haven't found them - so I might uninstall Visa and EasyScopeX. 

I wouldn't disagree with some of these descriptions (from EEVblog):

"Has anyone got EasyScopeX working with their Siglent scope at all? Darned if we can get it working, pesky thing".

"Visa seems to work without any problems but EasyScopeX just crashes as soon as we try to run it".

Webserver allows the scope to be remotely used - it works very well
Using the webserver that is built-in to the scope provides a better user experience, by far! I used it previously to issue SCPI commands but my initial impression is that the Instrument Control is READ-ONLY. It continuously updates but the scope controls that can be enabled on the RHS are not visible and making it full screen doesn't help. The Siglent User's Manual describes setting up the webserver e.g. with DHCP but doesn't go to describe how to use it. Fortunately, there is a Siglent NA "demo" video that demonstrates "the click" that enables the controls to be made visible.

Thereafter it works just like using the scope, except the rotary controls are separated out as an LH rotate, click and RH rotate buttons. It really is like using the scope and everything works as you might expect. Using the scope directly is perhaps easier, but it would be OK for remote working.

Unlike EasyScopeX, which takes control of the scope, the real scope can be used at the same time when accessing via the webserver. The scope seems unaware that it isn't being used directly. Saving a picture, saves to the scope e.g. to a USB stick and I haven't found a way to save remotely - probably a limitation of using a browser.

Here are some shots from my Mac of remote operation. The FFT of the scope's 1K square wave updates in real-time and operation of the interface is like the real thing using the webserver (and not EasyScopeX). The scope identifies and labels the peaks, sorts them and what you get matches the theory e.g a square wave is a base with harmonics of 1/3 amplitude at 3x base, 1/5 at 5x, etc. Looking at the FFT, one might realize that the base frequency is what the scope FFT calculates: 954Hz vs real (see RHS displayed: 1KHz).

I could use the "Run Stop" button like the real scope, switch from displaying "peaks", to "markers" and adjust the points to allow measurements at the harmonic frequencies, and use show "Show Delta On" to add extra info to the table. Being remote has its disadvantages e.g. I can add channel 2, but I've not found a way to "remotely" attach the probe...

Finally, looking at the table, the graph, etc., and comparing it to a known square wave FFT, shows it has done an excellent job!

The only way I found to get the data back on the remote Mac, is to take a screenshot (like the two attachments). Clicking the print button is also able to save on the scope e.g. to a USB stick. In a day or so, I will have the WiFi set up, so no 25' cable through the house. I never realized, but modern, ultra-thin laptops no longer have ethernet ports. Perhaps future scopes will automatically include WiFi and not need a dongle?

Simon

[tautech]

Saving a picture, saves to the scope e.g. to a USB stick and I haven't found a way to save remotely - probably a limitation of using a browser.

The only way I found to get the data back on the remote Mac, is to take a screenshot (like the two attachments). Clicking the print button is also able to save on the scope e.g. to a USB stick.

You missed the Save Waveform virtual button at the foot of the webserver page. That grabs a screenshot just like the blue Print button but instead drops it directly into your browsers Download folder. Same small file type PNG screenshot as when using the Print button.

Being remote has its disadvantages e.g. I can add channel 2, but I've not found a way to "remotely" attach the probe...

 
When you find out the way to do that please post it here ! 

[tttonyyy]

EasyScopeX works fine for me. I can still take control of the scope front panel and ask the software to refresh regularly to reflect what changes. I can see this being useful when doing a Teams conf call to demonstrate something - much quicker than writing an image to usb stick, transferring to a pc and attaching to a chat.

[SimonM]

You missed the Save Waveform virtual button at the foot of the webserver page. That grabs a screenshot just like the blue Print button but instead drops it directly into your browser's Download folder. Same small file type PNG screenshot as when using the Print button.

I hadn't had a chance to explore these additional buttons:

1. Screen Save - saves a .png file locally;
2. Waveform Save - saves a binary file of the waveform;
3. Bin_2_CSV_Tool - provides a Windows utility to convert the binary file.

Screen Save was the virtual button I needed!

Bin_2_CSV_Tool - interesting but not universally executable
The Waveform Save virtual button also saves the waveform as a compressed binary file (13MB). I also used the Bin-2_CSV_Tool Windows Application to convert it to a big .csv file (260MB). I had mixed results with the Bin_2_CSV_Tool. On one Windows machine, it worked fine but on another, I had the usual cryptic Windows messages about compatibility problems. The Bin_2_CSV_Tool also includes (for reference) a Python script. Since I'm mostly on a Mac, using the script would be preferable to running the Windows Application under VMWare Fusion. When I tried to run it, Python complains about uninitialized variables (line 106). The file is interesting and since Siglent also publishes the format of the binary file, I may have another look at the script. Easier to work with it than starting over with just the spec.

Small .bin converts to an enormous .csv file
With the Windows App (on another machine), loading the generated .csv highlights just how much data the scope is working with, which when you are looking at the scope and adjusting it, you mostly take for granted - since it all works. One way to cut back the amount of data that the program produces is to limit the collection e.g. memory depth. There are some Siglent NA videos on how to use it with MS Excel.

MS "solution" to this "compatibility" problem, is to suggest reinstalling the application and trying again, with predictable results. I will probably get a better "solution" by undoing the prerequisites for the Visi program that were introduced - some old .net 2 & 3 libraries. One of the reasons why I try to avoid using Windows.

SDS1000X-E Service Manual - verifying scope's pass/failure criteria
The Service Manual has an interesting (to me) chapter on verifying the mainboard including how to set it up e.g. with/without a 50-ohm termination load (scope doesn't have a switchable input). Measuring the pass/failure criteria e.g. DC gain, offsets, time base, trigger delays, external triggers, noise floor, bandwidth, etc. everything being based on the SDS1202X-E or SDS1204X-E - one (only?) H/W difference being the input capacitance of the 4-channel scope.

I assume a 50-ohm termination is simply a 50-ohm added across the input terminals to ensure that equipment is currently set up to avoid reflections (distortion) and scaling issues (impedance mismatching).

Maintaining the sample rate
The Service Manual repeats a statement: "When a single channel per pair is active, that channel has a sample rate of 1 GSa/s". I had interpreted this to mean that if channel 1 was used without channel 2, the 1 GSa/s would apply to channel 1 when channel 3 and channel 4 were both active. You can see from enabling "dot" rather than "vector" with a Run/Stop (== stopped) and a 2ns/Div timebase, that all the channels drop back to 500 MSa/s (just join/count the dots). So, it is worth remembering that using channel 1 alone, channel 2 alone, channel 1 and channel 3 together, or channel 2 and channel 4 together, provides the highest sampling rate for the 4-channel scopes.

Simon

[tautech]

You missed the Save Waveform virtual button at the foot of the webserver page. That grabs a screenshot just like the blue Print button but instead drops it directly into your browser's Download folder. Same small file type PNG screenshot as when using the Print button.

I hadn't had a chance to explore these additional buttons:

1. Screen Save - saves a .png file locally;
2. Waveform Save - saves a binary file of the waveform;
3. Bin_2_CSV_Tool - provides a Windows utility to convert the binary file.

Screen Save was the virtual button I needed!

Bin_2_CSV_Tool - interesting but not universally executable
The Waveform Save virtual button also saves the waveform as a compressed binary file (13MB). I also used the Bin-2_CSV_Tool Windows Application to convert it to a big .csv file (260MB). I had mixed results with the Bin_2_CSV_Tool. On one Windows machine, it worked fine but on another, I had the usual cryptic Windows messages about compatibility problems. The Bin_2_CSV_Tool also includes (for reference) a Python script. Since I'm mostly on a Mac, using the script would be preferable to running the Windows Application under VMWare Fusion. When I tried to run it, Python complains about uninitialized variables (line 106). The file is interesting and since Siglent also publishes the format of the binary file, I may have another look at the script. Easier to work with it than starting over with just the spec.

Small .bin converts to an enormous .csv file
With the Windows App (on another machine), loading the generated .csv highlights just how much data the scope is working with, which when you are looking at the scope and adjusting it, you mostly take for granted - since it all works. One way to cut back the amount of data that the program produces is to limit the collection e.g. memory depth. There are some Siglent NA videos on how to use it with MS Excel.

Yes data files get big quick unless you set trigger conditions to control the size and just work with that capture.

SDS1000X-E Service Manual - verifying scope's pass/failure criteria
The Service Manual has an interesting (to me) chapter on verifying the mainboard including how to set it up e.g. with/without a 50-ohm termination load (scope doesn't have a switchable input). Measuring the pass/failure criteria e.g. DC gain, offsets, time base, trigger delays, external triggers, noise floor, bandwidth, etc. everything being based on the SDS1202X-E or SDS1204X-E - one (only?) H/W difference being the input capacitance of the 4-channel scope.

I assume a 50-ohm termination is simply a 50-ohm added across the input terminals to ensure that equipment is currently set up to avoid reflections (distortion) and scaling issues (impedance mismatching).

Yes Performance verification uses an external signal sources which are typically from a 50 Ohm source so therefore they must be correctly matched with a 50 Ohm pass through termination otherwise scope performance can't be accurately judged.

Maintaining the sample rate
The Service Manual repeats a statement: "When a single channel per pair is active, that channel has a sample rate of 1 GSa/s". I had interpreted this to mean that if channel 1 was used without channel 2, the 1 GSa/s would apply to channel 1 when channel 3 and channel 4 were both active. You can see from enabling "dot" rather than "vector" with a Run/Stop (== stopped) and a 2ns/Div timebase, that all the channels drop back to 500 MSa/s (just join/count the dots). So, it is worth remembering that using channel 1 alone, channel 2 alone, channel 1 and channel 3 together, or channel 2 and channel 4 together, provides the highest sampling rate for the 4-channel scopes.

4ch X-E are one of few in this class/price point that use 2 ADC's each 1 GSa/s so channel use management is required to maintain best sampling rates for when it might matter.
1&3, 1&4, 2&3 or 2&4 channel usage combinations all return 1 GSa/s max sampling rates by using one channel on each 1 GSa/s ADC whereas if using any 2 channels on either ADC reduces the max sampling rate to 500 MSa/s.
The user should also be aware each ADC has 14 Mpts of memory support that is halved when any 2 channels are used on one ADC however if just one channel is used on each ADC memory max depth remains at 14 Mpts/ch.

[DEV001]

Another tip for new 1104X-E users, RF-Loop's various posts on how the unit works and the linked post from Performa01 which contains several PDF documents that detail almost every function the 1104x-E has.

IMO, the official Siglent user manual while adequate doesn't provide nearly as much detail as the analysis below.

https://www.eevblog.com/forum/testgear/siglent-sds1104x-e-in-depth-review/

Just one of the many write-ups from RF-Loop on the 1104x-E.
https://www.eevblog.com/forum/testgear/siglent-sds1x04x-e-bodeplot-ii-(sfra)-features-and-testing-(coming)/

[SimonM]

I really have to change my SSID just to configure and use the TL-WN725N WiFi dongle?
If I read it correctly (Jason from SiglentNA) advises: "XE firmware being incompatible with SSIDs and PSKs that have spaces or special characters" and the solution is just to not use them.

Perhaps I don't read the 802.11 standards correctly, because using English-like characters (other languages too) is a "convenience" but not a "requirement" and an SSID can be up to 32 octets of just about "anything", so "do not have spaces or special characters" doesn't begin to describe the problem...

Simon

[DEV001]

I really have to change my SSID just to configure and use the TL-WN725N WiFi dongle?
If I read it correctly (Jason from SiglentNA) advises: "XE firmware being incompatible with SSIDs and PSKs that have spaces or special characters" and the solution is just to not use them.

Perhaps I don't read the 802.11 standards correctly, because using English-like characters (other languages too) is a "convenience" but not a "requirement" and an SSID can be up to 32 octets of just about "anything", so "do not have spaces or special characters" doesn't begin to describe the problem...

The TL-WN725N was supposed to arrive today. Tomorrow's task - explain why the home WiFi might be broken and how to "fix it" for a small array of WiFi widgets we have that was working just fine until now.

Simon

Another inexpensive option is to use an wifi router/extender/wireless bridge to authenticate to your wireless network and connect the scope ethernet port to one of the ethernet ports on the access point. You can use many inexpensive wifi routers to do this or flash OpenWRT/DD-WRT/Tomato, etc... to an older wifi router and you should be good to go until Siglent corrects the issue in firmware.

It isn't ideal but if all you have is WIFI access and you don't have the ability to change the SSID this may be an alternative option.

An example, this router looks like it supports wireless bridging for $19.98
https://www.amazon.com/TP-Link-TL-WA901ND-Wireless-450Mbps-Repeater/dp/B0857K4KVZ

[tautech]

Dropping a link to this post with an excellent illustration of LAN connection and explanation of DCHP principles for reliable connections:
https://www.eevblog.com/forum/testgear/siglent-ethernet-and-wifi-connection/msg3594083/#msg3594083

[SimonM]

I really have to change my SSID just to configure and use the TL-WN725N WiFi dongle?
If I read it correctly (Jason from SiglentNA) advises: "XE firmware being incompatible with SSIDs and PSKs that have spaces or special characters" and the solution is just to not use them.

Hyphens are OK but spaces and a few other characters are not)
My SSID includes by default hyphens e.g. BT-XXXXXXX. That's OK and the scope and WiFi adapter connects OK. If I change it, spaces and some of the other restricted characters won't allow WiFi to connect. The router has its own set of restrictions e.g. spaces at either end of the SSID are excluded and well documented by the BT Help.

So, it turned out to be a non-event (for me) because hyphens are accepted and the scope WiFi connection works great. With five WLANs at home (and each defaulting to hyphens (-) in the SSID), that's good.

Scope and WiFi adapter seem to "play well" with a home router
I'm only using a "cheap" tp-link TL-WN725N adapter (about £8 from Amazon) that is restricted to the 2.4GHz band, with excellent range and speeds up to 150 Mbps that works perfectly. tp-link also has a dual-channel adapter TP-Link AC600 (Archer T2U Nano), but no real advantage using the 5GHz band that can be more "range restrictive" and some users report needing a separate Windows driver that's not required with a TL-WN725N adapter, so is most likely incompatible with the scope. Confirmed: TP-Link AC600 (Archer T2U Nano) is 2.4GHz/5GHz is definitely NOT compatible with the scope.

The shielding on the scope doesn't seem to be a problem e.g. it works well enough, with the adapter in the rear USB slot and any shielding by the metalwork of the scope doesn't obviously impact the performance, unduly.

Mostly I will try to use a LAN cable, but it's good to know that, if required, it also has a good WiFi range and I can now say "goodbye" to a 25' trailing LAN cable that goes between two rooms at home - that seems to be unpopular, for some unknown reason!

Can you keep a secret?
I noticed that the pre-shared keyword (PSK) secret password isn't quite so secret - see the screenshot:



WiFi connect (and future reconnects after a power cut are good)
Once the WiFi is ON (connected) the scope will be ON (connected) the next time the scope is powered up. That's a good thing e.g. if the scope is configured to start after a power cut, then the WiFi connection is restored automatically, even if there is a delay as the router restarts and it keeps retrying the connection until it succeeds. 

Simon

[SimonM]

Adding SDG1032X Function Generator - phase angles
Having just bought the Siglent SDS1104X-E scope, and being pleased with it, I decided that I needed a 2 channel signal generator...

I have just bought and started to use a Siglent SDG1032X Function Generator.

We all make mistakes
Being somewhat new to having a signal generator, I connected Function Generator to the scopes using a BNC cable and a 50-ohm terminator at the scope end for channel 1.

I don't have a second BNC cable, so I have the second channel of the Function Generator with another 50-ohm terminator and a probe to scope 2nd channel.

With both channels on and triggering on channel 1, I can only "see" channel 2. The Function Generator defaults to locking both outputs.

Recognizing my "rookie" type mistake, I realize that the output from channel 1 is being exactly overlaid by channel 2.

How to fix a phase angle?
I now have changed the setup to have channel 1 and channel 2 of the Function Generator locked so that only channel 1 can be varied.

Both channel outputs are terminated with a 50-ohm terminator and the FG is set on both channels to 50-ohm.

I have two scope probes in 10x connected from channel 1 and channel 2 of the scope to the output of both 50-ohm terminators.

The Function Generator is now set at 10MHz with a sine wave. That's about the upper end of what I want to use the FG for, hence the purchase of an SDG1032X.

I see that the signal from channel 1 is being exactly overlaid (almost exactly) by channel 2.

Knowing that there are two groups of channels on the SDS1104X-E, I have started to use channel 1 and channel 3 as my two inputs. With both probes, are set to 10X and calibrated to the 1KHz square wave test. The scope has been reset to factory defaults and then all four probes set to 10X. The scope has been switched on for at least an hour and calibrated (takes about 5 minutes).

Triggering on channel 1 and connecting the "same input" to channel 2 where it's in phase:



Triggering on channel 1 and connecting the "same input" to channel 3 or channel 4 it's not in phase:




I can repeat this, triggering on channel 3 and connecting the "same input" to channel 4 where it's in phase:



Triggering on channel 3 and connecting the "same input" to channel 1 or channel 2 it's not in phase:




When I say "same input", I had initially set up the scope like the 1KHz setup. Thinking that the FG might not produce a signal that really was in phase, I connected both probes to the same 50-ohm output. That makes no difference. I have also switched the probes around to see if there is a phase difference between any of the four probes - they are the same.

So I have come to the conclusion that for the "same input":

Scope shows, (triggering on channel 1):

1. Channel 1 and channel 2 in phase;
2. Channel 1 and channel 3 not in phase;
3. Channel 1 and channel 4 not in phase (with the same phase difference at 10MHz).

Similarly, scope show, (triggering on channel 3):

1. Channel 3 and channel 4 in phase;
2. Channel 3 and channel 1 not in phase;
3. Channel 3 and channel 2 not in phase (with the same phase difference at 10MHz).

I'm not reliant on probes or the FG outputs to introduce the phase problem.

Would I be wrong to think that the scope needs some extra adjustment to bring everything back "in phase", or am I expecting too much?

NB I can show that the probes and the FG provide the same or an identical in-phase signal back to the scope.

Simon

[tautech]

Would I be wrong to think that the scope needs some extra adjustment to bring everything back "in phase", or am I expecting too much?

Yes
Channel Phase locking is done in the SDG.....investigate the settings. 

Another tip if/when you need to trigger on a channel but don't need to see that waveform is to hide that channel and that functionality is in every channel's menu on P2.

[StillTrying]

Are you saying that the scope's CH 1+2 are not in phase with CH 3+4.

If that have a look at SKEW while you're there.

[bdunham7]

Keep it simple and use two probes, one for CH1 and one for CH3 and display only CH1 and CH3.  Offset them a bit if it helps.  Connect both probes to the same channel of your SDG, eliminating all doubt as to phase.  Pick one to trigger from and then observe which one leads.  Leave the probes connected at the SDG and swap them at the scope.  If the same channel still leads, your scopes two acquisition units are not aligned, which is appears to be the issue.  If the channels change relative positions, the issue is in the delay characteristics of your probes. 

Now press CH1 and then Next Page.  The second button should read DESKEW and a time indication.  If this reads 0 and the channels are that far off, IMO your scope is defective, unless there is some way to calibrate the base deskew number.  You can press the DESKEW button and turn the small universal knob to adjust the position of the traces, but you should not have to do that with identical probes, certainly not for a correction of several nanoseconds.  Do check the DESKEW setting on all 4 channels to make sure someone hasn't set them this way.

FWIW, a quick check on my SDG2042X-E and SDS1104X-E show that the scope has a 1-3 skew of about 90ps and the sig gen about 270ps when the channels are copied but not coupled.

EDIT:  After a 30-minute warmup and a self-cal, my scope's 1-3 skew seems to have gone away altogether, best match is at zero now.  The sig-gen still is 270ps, which is about 12 degrees phase difference at 100MHz.  I'm not sure why that would be.

[SimonM]

Would I be wrong to think that the scope needs some extra adjustment to bring everything back "in phase", or am I expecting too much?

Yes
Channel Phase locking is done in the SDG.....investigate the settings. 

Another tip if/when you need to trigger on a channel but don't need to see that waveform is to hide that channel and that functionality is in every channel's menu on P2.

Thanks. I can confirm:

I have channel 2 locked to channel 1. So I cannot change channel 2.

If I probe to channel 1 and channel 2 of SDG using scope channel 1 and channel 2, then they are both "in phase".

I can, of course, turn channels on and off, but I left them all on to show that the settings are the same and only switching inputs, to show a phase change.

I now have channel 2 of SDG off and both probes 1 & 3 on SDG channel 1 after a 50-ohm terminator. I get a phase shift.

So with two probes on the same source, I wasn't expecting any phase shift.

I can also replace probes 1 & 3 with probes 2 & 4 (all set to 10x) to show the same phase shift. Or swapping 2 & 4 to get the same phase shift.

So, I'm sure it's not the probes and there is only one channel of the SDG being used.

FWIW, SDG with one or two channels works very well - that's why I bought it!

Simon

[SimonM]

Are you saying that the scope's CH 1+2 are not in phase with CH 3+4.

If that have a look at SKEW while you're there.

Thanks.

Yes, I'm saying 1 & 2 of scope are in phase and 1 & 3 or 1 & 4 are not in phase.

I didn't know about the skew... until now.

I can get 1 & 3 to be in phase by adjusting the skew of channel 3.

The two traces appear to be completely aligned when it is set to -29.35ns.

I can also measure the skew difference, which averages about 400ps.

The skew can be set to a number by depressing the adjust button. There is also a default, or clear, that puts the skewback to 0.

On the function generator, I can increase the frequency e.g. from 10MHz, by 1MHz increments, to 15MHz.

When I change the frequency, the scope trigger still functions and the sine waves get closer together, as you would expect.

They also stay in phase (with skew set to -29.35ns) across different frequencies (10MHz, or lower and up to 15MHz).

If I switch to using channels 1 & 4, I can set the skew of 4 to stay in phase and it's also -29.35ns to get them in phase.

Simon

[SimonM]

Keep it simple and use two probes, one for CH1 and one for CH3 and display only CH1 and CH3.  Offset them a bit if it helps.  Connect both probes to the same channel of your SDG, eliminating all doubt as to phase.  Pick one to trigger from and then observe which one leads.  Leave the probes connected at the SDG and swap them at the scope.  If the same channel still leads, your scopes two acquisition units are not aligned, which is appears to be the issue.  If the channels change relative positions, the issue is in the delay characteristics of your probes. 

Now press CH1 and then Next Page.  The second button should read DESKEW and a time indication.  If this reads 0 and the channels are that far off, IMO your scope is defective, unless there is some way to calibrate the base deskew number.  You can press the DESKEW button and turn the small universal knob to adjust the position of the traces, but you should not have to do that with identical probes, certainly not for a correction of several nanoseconds.  Do check the DESKEW setting on all 4 channels to make sure someone hasn't set them this way.

FWIW, a quick check on my SDG2042X-E and SDS1104X-E show that the scope has a 1-3 skew of about 90ps and the sig gen about 270ps when the channels are copied but not coupled.

EDIT:  After a 30-minute warmup and a self-cal, my scope's 1-3 skew seems to have gone away altogether, the best match is at zero now.  The sig-gen still is 270ps, which is about 12 degrees phase difference at 100MHz.  I'm not sure why that would be.

Thanks. I do have it all simplified down to only using one source which is SDG channel 1. channel 2 is off.

I was using both channels of the SDG to avoid having to put both probes into one BNC and hold them there.

With only one SDG output enabled, I can manually de-skew (is that a verb?) to align them.

I can swap the probes to show that it is independent of a phase shift in the probes.

I can switch off unused channels.

-29.35ns seems a lot to adjust something. A few 10's ps would be acceptable.

So, is there a way to "calibrate" the skew, so that the channels are in phase with a skew on all channels set to 0?

That's also how I would expect it to come from the factory.

There is also a "Quick Cal" in Utility, that is set to "On". Setting it to "Off" doesn't seem to make a difference.

Simon

[bdunham7]

-29.35ns seems a lot to adjust something. A few 10's ps would be acceptable.

Agreed, that sounds broken.  I have no idea how it is broken or what malfunction would cause that.  29ns is roughly the equivalent of 20 feet of coax.  It is possible that there is some calibration setting that is grossly off, so contact Siglent to see if they have some method of changing that or if they want to exchange it.

de-skew (is that a verb?)

delime, delouse, deskew....sounds good to me.

[StillTrying]

It's odd, we've never seen that one before, with 4 near identical probes all the 4 channel skews on 0 should do.
Did you remove all 4 probes for the warmed up self-cal.

[SimonM]

It's odd, we've never seen that one before, with 4 near identical probes all the 4 channel skews on 0 should do.
Did you remove all 4 probes for the warmed-up self-cal?

Thanks. All the probes are the ones supplied and the type is pp510. For the warmed-up self-cal, I followed the instructions to remove all the probes. I would assume that, if the skew between different channel pairs can be set up and measured, then it can also be calibrated down to close to zero during a self-cal.

Simon

[tautech]

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.

[SimonM]

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):



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

Simon