SDG 1020
Software Version: 1.01.01.27
Hardware Version: 0f-00-00-21-22
Serial Number: SDG00001120xxx
1 Hz square wave with 50% duty cycle on channel 1:
All we know that electronics is art and it also can be and need be fun.
Square risetime is <10ns (typically 6-8ns in this Siglent model)
In your image you perhaps have one sample every 2us. 2us is 2000ns.
(with 16k sampling buffer your Rigol have 0.5MSa/s with 500us horizontal speed)
It can draw straight line between 2 sample points (just as your rising edge in zoomed window if there is good luck that real rising edge is just between these sample points)
You really can not see any glitches there due to this extremely low samplerate.
And for jitter. You are looking same rising edge where is your trigger. Yes you can test your oscilloscope trigger quality/jitter but not signal source timing jitter with this method.
This 0.5MSa/s sampling rate is too low for all this kind of purpose. But yes, it produce nice art draw on the screen. For analyzing 1Hz square wave timing jitter: nearly impossible with your scope.
You need reliable trigger on rising edge and then go to look next riring edge! 1 second! How you do it if thewre need enough resolution for reliable jitter measurement. You have max 1M memory. With 1s period theoretical maximum is 1MSa/s. With 500ksa/s you have 2 second. Can you set trigger to rising adge and take next rising edge on the screen... and there you have 2us time resolution. Is it enough? Yes it is if think that specified jitter for Sqrwave is 0.1% of period (@ 1kHz typical) But wait... 50ms/div and more slow your Rigol go to scroll mode!
So, game over for real jitter measurement with Rigol DS1000E for 1Hz square.
Btw.. you are looking 1Hz square and your input is AC coupled. (yes you can see this rising edge but if you turn to speed where you can see whole cycle... well you see only peaks up and down where is rising and falling edges. But yes with only this short time period it can do.
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This your SDG1020 is old version.
I have not tested this version SDG10
20 but I have tested this same version SDG1010 and 1025. They did not have this special CH1 square wave problem where it out "burst" of pulses before real edges using low frequencies + high level of glitches near rising and falling starting corners. (when these glitches duration is enough long and high they make siggle or several random burst of real flat top pulses.
Strange here is that these new glitches with high level can see in different time position than this other "glitch" issue what is talked earlier an where PECL comparator hysteris setting was wrong (too narrow). Typically this was common to both channels and around same. Also these special glitches looks reduced in these new versions.
It looks more and more like it is in SDG1020 and if it is PCB version 02. (until find opposite information) and they are made 2013.
I have tested several SDG1010 with this new PCB 02- version and no any sign about this issue.
Also new SDG1010 where is PCB version 02-: it looks that square corner glitches level is more low than units what I have tested before. (dependent of FW there may read HW 0f- or 00-)
PCB version is first two digits in HW version string.
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But for low frequencies. WHY use square wave function at all? There is pulse function up to 5MHz.
After 5MHz up to 20 or 25MHz there can use Square function typically without problems.
Perhaps Siglent can shut off this Square function example under some some frequency... example 100kHz or something like it.
Btw, with higher frequencies timing jitter is less than pulse mode what have always 8ns due to 125MHz clock and simple machine principle.
Example. How much is 1MHz square wave timing jitter? (even with these units what have problem)
1ns or something like this from ideal edge time?
With pulse function 8ns
1kHz
square wave (in good condition normal unit)
0.1% from cycle time 1us = 1000ns (and becouse not explained, it can not say if it is from ideal time point or peak-peak. (my measurements looks like from ideal time point)
1kHz
pulse 8ns p-p (+ some small other kind of jitter if look more deep in practicde and theory)
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Open recommendation to Siglent:
Simple free solution what may solve many problems:
Please: In next FW update, shut off Square wave function example <100kHz freq.
And then write new specs sheet.
Square wave: 100kHz - 5, 10, 20, 25MHz depending model.
There is no any need for special square wave function under 100kHz.
For under 100kHz there can use Pulse function.