Need help with Siglent 1102CML. Weird Stuff happening - Page 1
Forum section: electronics / beginners

author: Gurpreet
author_rank: Contributor
timestamp: May 06, 2016, 01:41:20 am
content: Just got a new Siglent 1102CML and I was tinkering around with it. Then I hooked up the 1Khz output that is on the scope to channel 1 and got the output as shown in the PIC1 attached below.I decreased the Volts/div to 500mV and i got the waveform as shown in the PIC2. Then I further decreased the Volts/div to 200mV and the waveform shifted below 0 reference by about 400mV and that you can see in the PIC3... after this I tried to move the waveform up using the position knob and to my surprise I cannot move it, though I can see the position of zero reference changing, u can see this happening in PIC4, also the wave keeps on getting more slanted at the bottom. I can't understand why.When I changed the Volts/div to 10V, I am getting 4V peak to peak as seen in PIC5 as compared to 3.16V in PIC1, 2.52V in PIC2, and 1.32V in PIC3I have DC coupling set on channel 1 at 1X. Probe I am using came with the oscilloscope. I have already compensated the probes properly.Is there something wrong with oscilloscope?? Help me to figure it out guys.

author: RobertHolcombe
author_rank: Frequent Contributor
timestamp: May 06, 2016, 03:30:37 am
content: The scope is only measuring what is displayed - if you count the number of divisions you will arrive on the same peak to peak value that the scope does.EDIT - not sure whats going on with the 500mV per division measurement though, should be ~2.00V peak to peak,

author: alsetalokin4017
author_rank: Super Contributor
timestamp: May 06, 2016, 04:30:18 am
content: Congratulations! You've discovered that using wrong or inappropriate settings on the scope produce garbage outputs!1. Use the 10x probe and channel settings unless your signal requires using 1x. For a 1 kHz square wave/pulse train at around 3 volts.... 1x is not appropriate.2. Don't overdrive your inputs by selecting too sensitive a V/div range for the signal you are measuring. The odd waveshapes are due to overdriving the input amplifier/attenuator stages in the scope's front end.3. Don't use too _insensitive_ a V/div setting either. The scope can probably only display 8 bits of vertical information, that is, 256 discrete levels of voltage. At 10V/Div this means that the full screen is 80V vertically (with some extra range not displayed at the top and bottom for slight excursions) so the voltage resolution is (approximately) 100/256 = 390 mV. So an error of 400 mV is only a single voltage step at that setting.4. The scope's automatic measurements are taken from what is actually shown on the screen, so if much of your signal is off-screen, it isn't taken into account in the automatic measurement computation.In short -- GIGO.(This topic is also discussed wrt the Rigol DS1054z in another thread....)

author: k4show
author_rank: Newbie
timestamp: May 06, 2016, 05:18:41 am
content: Quote from: alsetalokin4017 on May 06, 2016, 04:30:18 amWhen would you use the 1X setting?EDIT: Nvm, just read this:http://www.ni.com/white-paper/14825/en/

author: tautech
author_rank: Super Contributor
timestamp: May 06, 2016, 06:29:53 am
content: Quote from: k4show on May 06, 2016, 05:18:41 amCommonly when checking a PSU or power rail for ripple.1:1 probes introduce capacitive loading to the DUT but there's little effect on low frequency low impedance circuits.Use the 10:1 settings as much as possible.Quote from: alsetalokin4017 on May 06, 2016, 04:30:18 amThis one, have a good studyhttps://www.eevblog.com/forum/testgear/ds1054z-distortion-issue/Quote from: Gurpreet on May 06, 2016, 01:41:20 amIf you've adjusted probe compensation for 1:1 probes settings that won't be of much use, they only need adjusting for 10:1 use.