Rigol DS 2072 noise problem   - Page 1
Forum section: electronics / testgear

author: playfsx
author_rank: Contributor
timestamp: July 24, 2012, 08:28:43 pm
content: Hi, before i start i must warning you, my english may hurt your eyes !Today i get in my hands the brand new rigol ds2072 , i love it !... forrrr ... aboutttt 40 minutes and then i discovery ... bugs and problems!! i mean whaaatt ?? i play with it only 40 minutes !So let's begin, the first bug it is about the usb host , well if you open the scope with the usb stich already inside, there is not mount it , not even unplug it and plug again. the solution is to open the scope without the usb stick and then plug in , not a big deal but steal annoying to plug an unplug the usb device all the time. I really want it all the time in so i can take print screen and save waves . RIGOL FIXX IT !The second problem is what i see spikes even if i don't have connect the probes and that really piss me off , so i take some pics , maybe you can help me with this one.===========================================================================================================with probe:a closer look:===========================================================================================================touching the tip:a closer look:===========================================================================================================with out probe:and the screen:===========================================================================================================close put not touching:and the screen:===========================================================================================================Hz:===========================================================================================================zoom in:===========================================================================================================I tried to close any other device in the room (including light bulbs ) i move it to another room but noting ... seem the problem to be the inside psu ....so i decide to make a "self calibration", i wait to finish and when it start up, not only there is no have fix it the problem but the expire all the trial version module who i have !! the scope come fully unlock (56Mpts i2c spi ....) for limited time (about 30 hours) ... all gone without even taste it ..next problem is ... well .. i try to measure the noise of the onboard regulator (5v) of my arduino and the give me AC sine with 38volts peak to peak ?!??!??!whhhhhhhhhhaaaatt ? i check my probe i check the configuration in the scope and i get my uni-t 61e to check it ! the uni-t give all most 5v with 10mv peak to peak, i try to get a pic right now and it's reading correctly , soo what going on?next ... this is not exactly a problem... this is a epic fail from the rigol with love :so i tried to install the drivers for this scope , i put in the cd and the only thing who i see is the manual and a readme.txtwith this inside:Setup Explanation:1??Download the USB driver from NI website-"NIVISAruntime.msi".2??Execute "NIVISAruntime.msi" to install the driver program.3??Execute and install the application software.well very convenient , a cd with a txt in it who tells you to download the software ... i mean yeah this what the cd meant for ..so if you can help me with the spikesupdate:I open the scope in the morning and it's working fine !! and the next night the doing the same !! so clearly something happening at the night !!

author: zaoka
author_rank: Frequent Contributor
timestamp: July 24, 2012, 08:36:59 pm
content: Take it to frends home and try to make sure there is nothing in the home that may cause that.

author: KTP
author_rank: Frequent Contributor
timestamp: July 24, 2012, 09:16:21 pm
content: It looks like a nice scope...comparable in specs if not slightly better than the DSOX2002 from Agilent for cheaper $$$.The noise does seem very consistent...I am with you that it is coming from internal and not external. I will be interested in hearing the solution.

author: Rosendorfer
author_rank: Regular Contributor
timestamp: July 24, 2012, 10:19:09 pm
content: Hi playfsxNo idea about spikes.... sorry..But seems You are the first one hire with hands on Rigol DS2000 series...I would love to hear anything good or bad regarding this scope.Rosendorfer

author: playfsx
author_rank: Contributor
timestamp: July 24, 2012, 10:46:26 pm
content: It's nice scope yes , but well i don't like the software , it can make it a lot better, for example the fft is pretty poor and really want to use that future ... im going to make a video review for this scope when i found the problem, so mabe that help you decide if worth the money or notso to the problem now,im gone try to another home tomorrow, but i don't this it going to change anything.. The only thin make me believe that is internal the problem is the freq. of the signal, is 100hz double the ac freq. in my home so probably is some bridge that it's double the freq. but why in day working correctly ? and why when im touch it the amplitude is going crazy, i mean 5v p-p is too much!

author: madworm
author_rank: Frequent Contributor
timestamp: July 24, 2012, 10:57:54 pm
content: If you touch the probe with your finger you get the line frequency sine wave. That is normal.

author: playfsx
author_rank: Contributor
timestamp: July 24, 2012, 11:53:04 pm
content: Quote from: madworm on July 24, 2012, 10:57:54 pmyes and ... no , i take the 50 ac main with 100hz spikes, the ac of the main it's ok the spikes is the problem

author: EEVblog
author_rank: Unknown
timestamp: July 25, 2012, 12:31:43 am
content: I was initially going to say it was LCD backlight driver (common issue with scopes), but then I looked at the frequency and it's 100Hz.Clearly it's the full wave bridge rectifier in the mains switchmode, somehow... Maybe the Y class suppression cap is involved?In any case the values are quite small. But when you advertise 500uV/DIV as a standout feature you want to be sure that stuff isn't visible.Dave.

author: playfsx
author_rank: Contributor
timestamp: July 25, 2012, 06:30:42 am
content: well i don't know for the power supply, i stay awake all the night to see what time it going to stop doing that , so i didn't open or close any device, i don't touch the scope and the best off all is, i make a video so you guys can have a clear pictureyou can see it in HDand is about 2 minutesso im thinking maybe the night it's more noise intro the ac lines and the psu can't reject it ? is any easy way to test if that is the problem , i try to measure the peak to peak before and after with the uni-t 61e but i don't see any difference in the ac .dave thanks for your reply , if you see the video im getting 160mv p-p with the probes, this is not small , i want to trigger low voltage signals and the spikes getting in the way, not mansion how bad is for the fft :/

author: armandas
author_rank: Frequent Contributor
timestamp: July 25, 2012, 07:41:41 am
content: Just a sanity check. Is your scope earthed?

author: flolic
author_rank: Frequent Contributor
timestamp: July 25, 2012, 08:50:34 am
content: Plug a BNC terminator and try again.

author: poorchava
author_rank: Super Contributor
timestamp: July 25, 2012, 04:17:49 pm
content: Maybe you've got a neighbor using some heavy duty ghetto construction high power device (like home made welder or something).Such devices are known to generate strong disturbances in AC lines if there is no proper mains filtering. In some countries connecting such equipment to a public grid line isofficiallynot allowed, you need to have permission and a proper high power connection. Of course what peoplke do in reality is whole different thing.

author: robrenz
author_rank: Super Contributor
timestamp: July 25, 2012, 05:24:15 pm
content: Improperly filtered variable frequency drives will also pollute the surrounding area with nasty noise

author: playfsx
author_rank: Contributor
timestamp: July 25, 2012, 05:53:14 pm
content: Quote from: poorchava on July 25, 2012, 04:17:49 pmi don't know about that , but im pretty sure what is some pulse in my ac line doing that , is any way to filter my ac power ? i mean i thinking to try a ups but im not sure if this is good idea, is any problem if i power the scope with out earth reference ? (im gone try disconnected from the ac line ) expect the ups what other device i can use to filter my mains ?

author: sotos
author_rank: Frequent Contributor
timestamp: July 25, 2012, 05:57:34 pm
content: Maybe you have a Dimmer for your lights or electronic transformer for them.They produce a lot of noise.I’m thinking, because you said only in the night you have the problem.

author: playfsx
author_rank: Contributor
timestamp: July 25, 2012, 06:10:34 pm
content: Quote from: sotos on July 25, 2012, 05:57:34 pmim not have dimmer , i don't thing to be any from my device that causing that , i have unplug every single device from all my house include light bulbs and try it, and accusal the spices become some mV more intensive

author: KTP
author_rank: Frequent Contributor
timestamp: July 25, 2012, 07:02:51 pm
content: I think a decent battery backup UPS to power your scope just for testing is a great idea. Those kind that are meant to work with digital equipment and computers (probably still a modified sine wave though). You could make a cable that leaves earth connected and disconnects the AC.

author: A Hellene
author_rank: Frequent Contributor
timestamp: July 25, 2012, 08:21:51 pm
content: Nice scope, playfsx! And welcome to the forum!The oscilloscope seems to be pretty much quiet, with a noise floor level of 520µV! *salivating*Of course, I certainly do not like these 2.5µs wide, 45/90/165mVpp periodical spikes, seemingly coming out of nowhere. They seem to be associated to the mains frequency.This is a long shot but, the scope must have an isolated mains zero-crossing or frequency detector circuitry in its PSU PCB, in order to be able to take readings synchronised to the mains frequency: You can see that signal at the olderRigol DS1000E/D PSU schematic sheetat the end of the first post, and how this signal can be selected as a trigger source (being fed into the fourth input of the LMH6574 multiplexer) at theTrigger/Comparator schematic sheet. So, since that signalisthere, it could accidentally interfere (through dirt, flux remains, a malfunctioning component, etc.) with its surrounding circuitry, and find its way to the display buffer under certain circumstances (temperature, humidity, etc.).Since the spikes seem to have a close relation to the mains frequency, try to power the device by a UPS, whose output frequency will eventually deviate from the mains frequency: Then you will know the source of the spikes, whether they are being induced internally or they are being picked up by the probes and/or the input amplifiers.As suggested previously, try shorting the input with a 50 ohm terminator and see if the spikes disappear. Do not be afraid also of powering the scope by a floating (ungrounded) UPS. Even though you would not be in any danger at all, just try not to touch any of its metallic parts, like the BNCs. Of course, you could always ground the device by grounding the UPS ground line.Try taking readings, making combinations of all the options above, while the scope would normally introduce those ugly but periodical and symmetrical spikes.-GeorgeEDIT: More info on the AC line trigger circuitry.

author: hans
author_rank: Super Contributor
timestamp: July 26, 2012, 02:43:51 pm
content: I've seen issues with oscilloscopes from other mains powered devices before too, like an airconditioning unit. I was debugging issues with some power supplies, AC coupling, 50 - 100mV/div and triggering on an 4-channel Isotek (I consider Isotek a 'B-brand') scope. Everytime to airconditioning unit starts or stops I saw spikes (because I was triggering in normal mode)I don't know how well the things where grounded there with earth, but I imagine quite bad because soldering stations was causing interference with an Aoyue hot air station as well.. If I turned off the Weller solder station, the Aoyue hot air station would briefly pulse on.So I'm pretty sure it's better to power it with earth reference.

author: playfsx
author_rank: Contributor
timestamp: July 27, 2012, 12:52:29 am
content: thanks for your answersI don't have a 50ohm terminator and i don't thing this is going to give any result at all, never the less i try to short the bnc connector with a 47ohm 1/4w resistor, and yeah i don't take any spikes , i don't expect anything else i mean is only 4mv with out the probes and with a so small resistor it is going to disappear.So i try more thinks ! I try to power the scope in another house and sure enough no spikes at all , not in the day not in the night !I power the scope with a ups in the same house and accusal when unplugged from the mains i see spikes and there is not difference if i ground the ups or not.This in not surprising i guess because the ups it's not sine wave capable.this measurement i take with the probe close to ups.So clearly my ac line have the problemI have a idea , what if im gone to accusal measure it, now i can't measure the mains directly but what if i try with a transformer, i mean if i have some spikes going to the primary coil i must able to see it on the secondary right ?The biggest transformer i have is 220 to 24v and sure enough i found some thing !!So let's make some math, the p-p of the secondary is 78.2 and the mains is 625v p-p , so the transformer ratio is 625/78.2 ~= 8The spike in the secondary is 9,28V p-p so in mains is 9,28 * 8 = 74,24V p-pWe now have the reason now how i can fix it ??My devices not cause that so i must some how filter the mains .I don't have try the ups of my friend in my home, so i don't know if the are going to fix anything if i buy one , but im thinking the only type ups it would be accusal work is the on-line ups and this is not cheap , is any other way to filter the mains ? preferably cheaper way ?

author: KTP
author_rank: Frequent Contributor
timestamp: July 27, 2012, 01:09:39 am
content: Wait. You tried a 50ohm termination (or you sort of made a 50 ohm termination using a 1/4 watt 50 ohm resistor with short leads at the bnc to ground) and the problem went away?This sort of points to the problem not being generated internal to the scope, but also means it is not coming into the scope over the mains.Maybe check with the downstairs neighbor and see if he is building a gocart in his bedroom with a TIG welder...

author: A Hellene
author_rank: Frequent Contributor
timestamp: July 27, 2012, 01:41:43 am
content: The 24VAC/50Hz transformer is very-very slow in response, and it should filter out those 2.2µs wide (~450KHz) spikes. This means that the spikes are probably created internally by some parasitic element, out of the AC line zero-crossing detector circuitry. Please read my additional material at my previous message.Try to read the 24VAC secondary of the mains powered transformer again, while the scope is powered by the UPS. Let's see if the spikes follow the peaks of the under test transformer waveform or the peaks of the UPS power supply. That is because the mains and the UPS waveforms will most probably be out of phase; and as all your captures show, the spikes follow the AC power supply peaks with a delay of ~1ms.-George

author: vk6zgo
author_rank: Super Contributor
timestamp: July 27, 2012, 04:28:46 am
content: To be quite sure of what you are seeing,you need to eliminate the Rigol from the test setup.Try to borrow another Oscilloscope,have a look at the secondary of the transformer again,without the Rigol plugged in.My guess is that you will see no spikes,Now plug the Rigol in & look for spikes,still with the other'scope.If the only time you see spikes is with the Rigol plugged in,it will point to the Rigol as the source.

author: playfsx
author_rank: Contributor
timestamp: July 27, 2012, 04:45:27 am
content: Quote from: KTP on July 27, 2012, 01:09:39 amI make one with 47ohm(i forget to mansion the 47ohm so i edit the last post) resistor and yes it went away, so if understand correctly that you said is that the probes are pick up this noise ?In my building the are living mostly students and now in the summer it's not here, it is however a small bar close to my house, maybe the have duty speakers doing something, i mean i have login what time the start and what time they stop and so far look like this:day 1: 21:40 - 5:20day 2: 21:48 - 4:20day 3:?? - 4:10Quote from: A Hellene on July 27, 2012, 01:41:43 amGeorge i relay try to understand but i don't have so much knowledge, i will however try again tomorow, maybe the clear head helps,Quote from: A Hellene on July 27, 2012, 01:41:43 ammaybe you have right, but im pretty curies accusal check it , now i don't have a function generation but i can use a 555i can get to 500khz easilyso this is my setup:i power the 555 form a 12v power supply , the output is connected with a 470 ohm resistor to the primary (220v) and i probe secondary (24v) with the ch2in the scope i use a average times 16 because it's not that stableso 590khz and not filterer, im pretty sure that the problem it's is not my scope, if it is im going to sent it back im not going to open it, it take me all most one year to gather the money im not going to lose the warranty ...Quote from: A Hellene on July 27, 2012, 01:41:43 amit's hard to take ups of my friend to my house , but i will try .Quote from: vk6zgo on July 27, 2012, 04:28:46 amnice point here, but i know only one who have a oscilloscope, it's my university and there is not even one at the million to borrow me one !still i don't thin that the rigol is the source, in the other house it working perfectly and in my home at the day .maybe i can try other sensitive device HMMmm .. im thinking my sound card but in not that sensitive and probably i will create a small explosion

author: notsob
author_rank: Frequent Contributor
timestamp: July 27, 2012, 06:33:40 am
content: This is probably a dumb question - "do you have fluorescent lighting ?", if answer is yes, have you tried turning it off. (I'm looking for a source of power spikes within your house)

author: madworm
author_rank: Frequent Contributor
timestamp: July 27, 2012, 07:50:37 am
content: I had a similar problem when toying with a current shunt amplifier (mV signal). Something was injecting spikes (different frequency and rep-rate). After eliminating everything else, it turned out to be my PC's power supply - of course it was running all the time, as I was consulting google.

author: JimmySte
author_rank: Contributor
timestamp: July 27, 2012, 08:16:32 am
content: Hi playfsxLast week I also purchased a DS2072 scope... I love it...I've been playing with it all week and in Dave's latest video he mentioned that someone on the forums was saving issues with their scope,so I powered mine up and ran the same tests as you did in your original post...long story short no issues in the signals on mine...here with the channel B lead floating... at my desk, in front of my pchere with the lead shorted out

author: playfsx
author_rank: Contributor
timestamp: July 27, 2012, 06:30:01 pm
content: thanks very much JimmySte your fist post and you try to help me, im all most sure the is not the scope any moreQuote from: notsob on July 27, 2012, 06:33:40 amyep and here is your answer:Quote from: playfsx on July 25, 2012, 06:10:34 pmQuote from: madworm on July 27, 2012, 07:50:37 ami have test i is one of my devices that doing that so it's no the case, maybe some else in the building doing something .. if this is the case i can not doing anything, only to filter this spikes.i search in google for filtering my mains and i found a device called Power conditioner (http://en.wikipedia.org/wiki/Power_conditioner) is this device going to help ? is anyone have try one of this ?

author: TerminalJack505
author_rank: Super Contributor
timestamp: July 27, 2012, 07:28:12 pm
content: You might try an appropriately rated (voltage/amps) line filter. A line filter is just a common-mode choke and a couple of capacitors so they're not terribly expensive. You might also clamp a ferrite core onto the power cable just for grins since they're even cheaper.

author: playfsx
author_rank: Contributor
timestamp: July 28, 2012, 02:11:35 am
content: Quote from: TerminalJack505 on July 27, 2012, 07:28:12 pmI have one nice big ferrite and i try it , the is seems to be not any difference, i gone find more details for the line filter and maybe try one,meanwhile i get the ups in my home for more testing, i make a video so you can see more details and i recommend to see it, maybe you can pick up something who i miss.but in short , if i power the scope from the ups (with out earth connection) and the probes is away from the mains i get only the noise from the ups. with ground connection i still getting spikes.If the probes is close to the mains and even is not power in the cable the probes can pick up the spikes, i tried to going the probes close only to the earth (ground cable) and i can still pick up noise.So i tried to measure the transformer while the scope is power from the ups as the A Hellene suggested , and i get the spikes , but this is not mean that this spikes existing on the ac line because the probes are probably pick up directly from the mains cable ( maybe can get it from the earth cable or maybe not ) , so my measurements probably are incorrect .so now im in dead end, if i must filter my mains i must do it for all the room , and maybe this is not going to work at all , maybe the noise coming from the gound( earth) cable and how i can filter that ?

author: zaoka
author_rank: Frequent Contributor
timestamp: July 28, 2012, 04:01:29 am
content: I think that you have problem with home grounding. Scope have filters built in for sure so there is no need to make new one.I would try to get isolation transformer and power scope with it,with ground lead disconnected, than measure your AC line and see what is going on. (just be carefull not to tuch metal parts during this measurement). try to measure between all combinations (neutral - ground, neutral -hot and hot - neutral)Also measure voltage between ground and neutral with AC multimeter when there is no problem as well as when problem appears.

author: T4P
author_rank: Super Contributor
timestamp: July 28, 2012, 04:16:09 am
content: I think you have an issue with a floating ground somewhere

author: tom66
author_rank: Super Contributor
timestamp: July 28, 2012, 11:13:15 am
content: Something I notice, the noise isn't at the peak of the waveforms, but slightly offset to the right: it is leading the voltage waveform. This makes me think the thing producing the noise is some kind of system with a PFC capacitor, perhaps a large motor installation? Maybe some kind of commutator arcing?

author: A Hellene
author_rank: Frequent Contributor
timestamp: July 28, 2012, 01:25:27 pm
content: playfsx, from your second video demonstration of the noise problem, and from thewalking spikesparts of it in particular, it seems that the mains line trigger circuitry of your scope is not responsible for the depicted interference, asI initially suspected.Now, here is an interesting waveform I captured, using my 100 MHz DS1052E:Ch1 to the mains line; Ch2 floatingChannel 1 was reading the mains voltage directly1, using a 100x probe, andChannel 2 was reading whatever it could pick up while unconnected, using the standard 10x probe, floating.Please note that it made no difference at all turning ON or OFF the 75W monitor (a DELL U2410) right in front of me, or the 250W halogen roof lamp (driven by a traditional and noisy phase-control TRIAC dimmer), or the 1.3KW room air-conditioning unit (the thermometer outside my window now reads 37 deg.C!). The captured waveforms were exactly the same, either the noisy units above were powered on or off.For those who will notice it, the mains voltage was externally measured to be 228.7 VAC RMS, while the DS1052E measured it to be 218 VAC RMS (DS1052E error: -4.7% or -3bit); in defence of the DS1052E, I will have to state that I did not warm it properly up before taking these readings, neither have I recently run auto-calibration2.The interesting parts in the captured waveform above are the time points -1.7div (-3.4 ms) and +3.3div (+6.6 ms), where Ch1 captures a couple of seemingly innocuous mains disturbances, which are absolutely synchronised to the Ch2 obvious spikes. The problem is that, though the Ch1 and Ch2 waveforms are out of synch by ~1.4div (~2.8 ms), the Ch1 and Ch2 spikes are in perfect synchronisation.Channel crosstalk, do I hear some of you murmuring? Well, maybe. But, by disconnecting the Ch2 probe, the second trace became a nice and clean flat line while the spikes at the first trace remained as they were exactly, and of the same shape and amplitude. So, I suppose that my scope is not really lying to me...This means that:1. The depicted spikes are probably generated erroneously within the oscilloscope front-end amplifiers.2. Our mains lines are actually that dirty.3. We are both being bombarded by who-knows-what kind of electromagnetic weapons(I am kidding!).What I can only say is that, in order to trust what my DS1052E tells me about my mains line spikes, I would have to repeat those readings with a higher class oscilloscope and not with another entry-level one.-GeorgeEDIT:1. DO NEVER TRY doing that if you are not absolutely sure of what you are doing, because the probe ground clip is the instrument's ground, which is hardwired to the mains power supply ground! Be very careful when messing with the mains line.2. More than half an hour later, the mains line was reported by the DS1052E to be 221 VAC RMS, while it was measured to be 223.2 VAC RMS.

author: Wim_L
author_rank: Regular Contributor
timestamp: August 03, 2012, 02:44:47 pm
content: I had a similar problem a while ago, with a bad Volcraft DSO-8104 (though probably a relabeled Instek GDS-2104). Lots of junk visible with a 100Hz period. I'll attach some old screenshots. The big dirty band was really a lot of tiny spikes, with some ringing.Confirmation came when I tested with another scope nearby. It measured a flat line on the same system (just a voltage source connected over a 100 or 180 ohm resistor, not an open probe!) but when the DSO-8104 was nearby and turned on or merely in standby (not connected to the same device being measured, just sitting on the same table plugged in), the analog scope also saw the same spikes! The power supply in that scope must have been causing some rather impressive EMI. Sent the thing back and got a different model of scope.And yes, grounding quality definitely can affect how heavily a power supply radiates. But some supplies are inherently better than others. An old Philips PM3206 or a newer (well, also discontinued now) Hameg 1508-2 never did it on those same power outlets.I'd definitely try getting another scope, perhaps some oldie analog, and seeing if you can measure the same spikes (for seeing short low repetition rate spikes on an analog, keep in mind Turning the trace brightness up and darkening the room may be required).

author: Teneyes
author_rank: Frequent Contributor
timestamp: August 25, 2012, 06:56:05 pm
content: QuoteHi All , Yes the DS2072 : Self-Cal has a bug that expires Options(Rigol confirms), BUT Rigol has sent me the options codes to restart the Trial Options,...I haven't try it yet.

author: Dread
author_rank: Regular Contributor
timestamp: September 07, 2012, 11:40:43 pm
content: Stop wasting time and send it back. From what I see in your videos there is something wrong with the switching power supply or some filter component has failed.

author: playfsx
author_rank: Contributor
timestamp: September 14, 2012, 10:33:47 am
content: Quote from: Dread on September 07, 2012, 11:40:43 pmThis is not the case, my mains is the problem i have confirm that look the second video, i only hoping now that the device that cause that they stop working now that the summer is over , one night accusal i don't get any spikesOverall im very happy with the scope, it have some software bugs but it's fixable .btw i upload a video to show the X Y capability's of the scope

author: hgjdwx
author_rank: Regular Contributor
timestamp: November 06, 2012, 05:35:42 am
content: Your Rigol DS2072 noise problem solved?

author: WLUWLU
author_rank: Newbie
timestamp: December 15, 2012, 10:26:44 pm
content: To my believe you don't have to fault the Rigol DS2000 series for the spikes you see. Don't forget the higher the sensitivity in the fronend the more the likelyhood of picking up unwanted signals. I have these for instance too but to verify ran a crosscheck with a Tektronix TDS1000 & TDS2000 series and exactly the same thing. Just a bit less visible since the TDS series don't have the fasted wfm update rate. This I think is more related to incoming via your probes and I would not make a snap judgement like "this is coming from within your DSO". I just e.g. plugged in the laptop charger into my HP Compaq 2510p (fairly old machine but used as my beater). As soon that switched mode PSU has to charge the laptop (thus being loaded) I see a big jump of "dirt" on my Rigol DS2102. That charger for my HP I bought last year from some chinese company as an OEM part but I doubt the quality. Once the HP has a fully depleted battery and I do switch it on (charging & running the same time) for the first 30mins or so that charger makes some really funny chirping noise which then disappears as soon a certain charge has been performed and it has to work a bit less. Me running about at least 2 laptops and some other goofy equipment (2 phonechargers & 1 DECT phone station) plugged in my noise floor in general is pretty high. Going higher in the mV input stage of the Rigol gets rid of it. If I run my other testkist along, like a Tek DSO, 2 bench lab DMM's, 1 Omnicron CMC net simulator, 1 Agilent 33120A, soem Grundig Digimess stuff nothing really happens because more decent testequipment usually employ better quality internal PSU circuitry vs some real cheapo consumer stuff.You could maybe try getting your lab EMI safe and improve general earth grounding and so forth but than you could as well spend thousands of $$ just trying to get it right.

author: marmad
author_rank: Super Contributor
timestamp: December 15, 2012, 10:39:26 pm
content: I believe he solved the problem with his mains supply months ago already. Perhaps he should mention it here - or else lock the thread.Oh, he did actually kind of mention it a couple of posts back.

author: tigerwillow1
author_rank: Contributor
timestamp: February 23, 2013, 11:27:46 pm
content: I see what looks like an unreasonable noise problem with the DS2072. I'm also new to DSOs so maybe there's something I don't understand. No matter what vertical sensitivity I'm on, I always have 3 or 4 bits of noise. I know to expect LSB error, but I thought that would only introduce one bit's worth of noise. For example, if I'm set to 1 volt per division with no input signal, the scope says and shows a 120 or 160 millivolt gap between the min and max level. It's not analog noise because it's proportional to the vertical sensitivity setting, always 3 or 4 bits. The result is the same if I leave the BNC input unconnected, shorted to ground, or terminated. The attached picture is a sweep captured at 1 volt/div with 75 ohm terminators connected, then expanded to 50 mV/div. Each A-D step at 1 volt/per div is 40 millivolts, which is what the picture shows. I expect the trace to "flop around" one bit, but not the 3 or 4 bits that I consistently see.Just to rule out electrical interference, I hauled the scope a hundred feet from the house and powered it from an inverter generator with identical results.

author: Hydrawerk
author_rank: Super Contributor
timestamp: February 23, 2013, 11:35:09 pm
content: This is weird. Write a message toDrieg, he sells those scopes and knows them well. He can give you an advice. There is something wrong with your DS2072, I think... But IMHO this fault is very rare.https://www.eevblog.com/forum/blog/the-dark-side-of-the-rigol-hack-bricked-scope-how-to-fix-it/

author: marmad
author_rank: Super Contributor
timestamp: February 24, 2013, 12:09:41 am
content: Quote from: tigerwillow1 on February 23, 2013, 11:27:46 pmMy DS2072 has the same noise characteristics as yours - and people seem to feel it's good for it's class. I'm no expert about these things, but from what I understand, many things contribute to the noise floor of an oscilloscope - the LSB error of the ADC being just one contributing factor. The front end of an oscilloscope is comprised of an attenuator, pre-amplifier and all of the path routing before the ADC - any one of which can introduce noise. And one other thing to consider - the DC gain accuracy for the DS2000 series is listed at ±2% full scale - which means, in essence, that signals smaller than 8 vertical divisions (in this case, noise) will have proportionally larger possible errors.

author: marmad
author_rank: Super Contributor
timestamp: February 24, 2013, 12:26:47 am
content: BTW, if you use the 'High Res' acquire mode, the pk to pk noise level will drop - sometimes significantly depending on the timescale.

author: drieg
author_rank: Regular Contributor
timestamp: February 26, 2013, 05:08:44 pm
content: Quote from: tigerwillow1 on February 23, 2013, 11:27:46 pmWhat you experience is normal on digital oscilloscopes, it is like digital zoom on your camera. What you see is a noise fluctuation betwen 3-4 quantization levels which is 1-2 bits, not 3 or 4 bits. You can see how the number of levels changes (usualy from 2 to 4) as you move signal up and down (with fine vertical offset), so the noise looks sometimes bigger (4 levels) and sometimes lower (2 levels). 1-2 bits are normal and usual on these units, so nothing wrong with your scope

author: tigerwillow1
author_rank: Contributor
timestamp: February 27, 2013, 02:36:20 am
content: Thanks all for the feedback about the A-D noise (not sure if that's the proper term here, but whatever is behind it, it has the appearance of noise). I'll say I'm disappointed, having assumed I'd be seeing the +/- 1/2LSB inherent in A-D converters. I also have to realize that even though paying for the DS2072 hurt, it's still at the low end of the DSO world. Its capabilities for what it costs are nothing short of mind-boggling, however that doesn't stop me from hoping for perfection. If anybody here has a different brand DSO and is curious enough to take the time, I'm very interested in finding out how the competition stacks up, i.e. how many different A-D steps it resolves a steady zero input to.

author: Teneyes
author_rank: Frequent Contributor
timestamp: February 27, 2013, 05:57:32 am
content: Quote from: tigerwillow1 on February 27, 2013, 02:36:20 amDoes anyone Know how the DS2000 is configured when the the input is set to GND with AC-DC-GND switch, as this quantisation level jumps does not show in this Stopped Frame digital Zooming?BTW Analog zooming works better than most DSO down to 500uV

author: drieg
author_rank: Regular Contributor
timestamp: February 27, 2013, 08:38:00 pm
content: @tigerwillow1: Here is my LeCroy DDA-120 / LC584AXL (8GSa/s, 1GHz, 16Mpts)

author: tigerwillow1
author_rank: Contributor
timestamp: February 28, 2013, 06:24:20 pm
content: Drieg - Thanks for that picture. It's looking more and more like I have an unrealistic expectation about the A-D resolution. This all started when I was looking at a rock-solid 13.5 volt input and the peak voltage readout said 15.1 . With the features come added responsibility in learning how to interpret them.Teneyes - I've concluded, rightly or wrongly, that the GND setting is a software feature. In the context of the live inputs, it's too perfect.

author: Teneyes
author_rank: Frequent Contributor
timestamp: March 01, 2013, 10:12:01 am
content: Quote from: tigerwillow1 on February 28, 2013, 06:24:20 pmNot sure what you were using to measure, As the DSO has Vpp, Vtop, Vamp Vavg measuring functionsand also CursorsCan you Capture the Display and PostAs for Noise the DSO is good and also is Sensitive ( with 500uV )Below I show a Scope Probe grounded to probe gnd in a Picture and a capture DisplayThenI show how this simple 8cm loop picks up signals and when I put my finger in the Loop the DSO gets a Larger signal. The Signal is a 94.9 FM radio station in the area (see cursor readings)With this scope you need to be aware of EMI signals ( lots of mains power)

author: tigerwillow1
author_rank: Contributor
timestamp: March 03, 2013, 05:02:20 pm
content: Maybe I can learn something here. These are pictures of what I was originally measuring. It's a steady DC level with a transient when it's shut off. The 10 ms. and 500 us. pictures are from the same single sweep, displayed at a different horizontal rate. I need a large vertical scale to capture the transient. In the 10 ms. picture the first unexpected item is the horizontal line being so "fat", which I didn't understand at first, and the second item is the max voltage reading of 15.2, when I knew darn well it was 13.5 . With the display changed to 500 us. the vertical noise starts to be evident. The 3rd picture, 1 us. sweep rate, is a different capture but shows the noise more obviously.I was expecting to measure the starting DC level using the peak voltage display. Average voltage doesn't work because of the level change. I could combine average voltage with cursors, but in this particular setup, it's a whole lot easier to just use a voltmeter. I first assumed I was picking up some kind of environmental or power line noise. When I ran the scope with terminators on the inputs and from a different power source I began to realize that the inaccurate reading is from the scope itself.