How do I get 1mv/div on the 1054Z?  I'm only getting 10mv/div - Page 1
Forum section: electronics / testgear

author: NeverDie
author_rank: Regular Contributor
timestamp: August 09, 2015, 10:17:48 pm
content: According to the specsheet, "Vertical Scale 1 mV/div to 10 V/div." Yet, it won't let me set it to less than 10mv/div. If I try setting it lower, it says "Parameter limited", whatever that means.What's worse, if I connect the ground clip to the probe tip, instead of getting a nice narrow flat line as I would have expected, I get a fat line instead (see attached screen shot). Is this scope just not capable of 1mv/div?I'm sorry, but 10mv/div just isn't terribly useful when working with arduinos.

author: Lightages
author_rank: Unknown
timestamp: August 09, 2015, 10:23:05 pm
content: Is your probe setting at 10X?

author: NeverDie
author_rank: Regular Contributor
timestamp: August 09, 2015, 10:33:34 pm
content: Quote from: Lightages on August 09, 2015, 10:23:05 pmIt was. Yet if I flip it to 1X, nothing seems to change. I still get a fat line, and it still won't let me do 1mv/div. Isn't that rather weird? Is there some probe setting I need to toggle somewhere to inform it which way the probe is set or something? Sorry for the bonehead question, but I'm a noob and I barely have any idea what I'm doing.

author: dom0
author_rank: Super Contributor
timestamp: August 09, 2015, 10:35:27 pm
content: You need to adjust the probe attenuation setting in the scope as well, or it will not show the correct vertical scale.

author: rs20
author_rank: Super Contributor
timestamp: August 09, 2015, 10:42:05 pm
content: Yes. Press "CH1" and there should be a probe ratio setting there.Why is 10mV/div insufficient for Arduinos? Normal Arduinos work would be at 5V or 3.3V peak to peak, so 500mV/div or 1V/div seems far more typical.Also, I recommend you watch the EEVBlog video about 1x probes - the frequency response is terrible. You should be sticking to 10x unless your doing work that is both low voltageandlow frequency.

author: NeverDie
author_rank: Regular Contributor
timestamp: August 09, 2015, 10:55:01 pm
content: Quote from: rs20 on August 09, 2015, 10:42:05 pmThanks! I set the probe itself to 1X and then I set it there at 1x as well. Now it let's me do 1mv/div.In answer to your question, I'm trying to measure the transmitter current through an NRF24L01+ module (an inexpensive 2.4Ghz radio module with, allegedly, a Nordic Semiconductor chip on it with that model number) driven by an arduino. Using a 1 ohm sense resister, with the previous settings I was getting the results below (see attached), and the lines were rather thick, making interpretation difficult (well, difficult to these noob eyes).

author: NeverDie
author_rank: Regular Contributor
timestamp: August 09, 2015, 10:59:19 pm
content: Attached is the test rig with DS1054Z probe attached.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 09, 2015, 11:00:06 pm
content: What about Arduinos makes 10mV/div insufficient? Logic level is 500 divs. If you're doing sensitive DAQ, you're probably better off testing it at larger signals (where distortion will be more exaggerated) and assuming it's fine at lower levels, using the DAQ itself to provide the data for analysis to confirm this (which will probably be easier than measuring it on the scope -- you can do the analysis on the MCU directly, or prepare and copy an array via serial and process a .CSV or what have you).Residual noise (noisy signal chain, switching supplies..?) might still be of interest, but this can at least be measured by the same methods, if not so easily tracked and troubleshooted.To get practical 1mV/div use, you can get a 1x or switchable probe (however: mind the limited bandwidth -- read the spec sheet for that gotcha!), a preamp or probe extender, or connect coax directly to the circuit (assuming it doesn't mind the capacitive load and reflection, or the extra loading if 50 ohm terminated), or using a buffer (to keep the gain but eliminate the loading). Speaking of noise, be mindful that such levels are very sensitive to ambient and conducted radiation (nearby radio stations can peak over 1mV in unlucky situations), so pay very close attention to grounding, shielding and lead dress.Also mind the limitations of bandwidth: typically a scope of that bandwidth will have maybe 0.2mV RMS baseline, mostly from the noise of a 50 ohm source. I believe Rigols aren't usually that good, and have some excess noise beyond that. A preamp in front (even with a low noise factor) will magnify the source noise, only making it worse (though not necessarily worse than the excess noise of the scope already).You can discard a lot of noise by narrowing the bandwidth (lower bandwidth setting, or "hi res" or averaging modes, or analog filtering the signal before the scope), but this may discard useful signal information as well. If your signal is periodic, you should trigger or sync from a much stronger related signal, then use averaging to remove noise unrelated to the signal (this correlates the signal, "pulling it out of" the noise).This is also helpful on older scopes that used software magnification for the lowest ranges (HP 54600B comes to mind). Quantization noise remains, but averaging can remove that noise (just as it works with any other noise source), getting a smooth signal back out. If you were hard pressed for resolution, you probably can't do this on the Rigol itself, but could save a CSV and do the math in a spreadsheet or MATLAB/Octave for the absolute finest resolution. (The latter also has the benefit of quickly and easily doing spectral and statistical studies, like autocorrelation.)Tim

author: NeverDie
author_rank: Regular Contributor
timestamp: August 09, 2015, 11:45:23 pm
content: So, with the 1X settings, I'm now able to get a better picture and can hopefully measure better. Looks like maybe I can go to a smaller ohm resistor and go from 5mv/div down to 1mv/div to get an even better measurement, if that makes any sense.

author: dadler
author_rank: Unknown
timestamp: August 09, 2015, 11:50:57 pm
content: In 10x mode you also better protecting the front end of your scope, by dividing down any transients.Most higher end scopes only come with 10x probes, as 1x use is rarely necessary--in addition to the downsides listed above.Here is Dave's video:http://youtu.be/OiAmER1OJh4

author: NeverDie
author_rank: Regular Contributor
timestamp: August 10, 2015, 12:41:21 am
content: Thanks, I'll watch that tonight.Speaking of noise, I was thinking of hooking the o-scope up to my computer via USB, and then I thought "Nah, that'll probably just inject even *more* noise into a situation where I want *less* noise." Is that likely to be true? I see that the USB cord that came with the Rigol appears to have big ferrite cores at both ends, so I'm thinking maybe there is a concern there, and that's the cheap way of (partially?) addressing it. Would a USB isolator also be worthwhile? If so, would it need to support USB 2.0 "high speed", or would USB 2.0 "full speed" be enough? Anyone know what speed is actually being used between the scope and a computer? It seems that most isolators use the same chip (the ADUM4160), and it doesn't support USB 2.0 in "high speed"mode.Or would the ethernet connection be preferable (or actually worse?) if noise is a concern? I have no idea.Also, would somehow running this scope off battery power rather plugging it into the wall help reduce noise at all? Or would it actually make it worse? Again, no clue, but you gents seem pretty smart and I bet somebody here would probably know.

author: rs20
author_rank: Super Contributor
timestamp: August 10, 2015, 12:51:41 am
content: Quote from: NeverDie on August 10, 2015, 12:41:21 amNot to be blunt, but these seem to be questions that you can easily investigate yourself through experimentation. Plug a USB cable in... see if the noise increases.Having said that, one would expect ethernet to be a more "noise-free" connection because any ethernet connection is galvanically isolated at both ends, eliminating the possibility of the creation of ground loops. But if you can't see the noise from a USB connection, then there's practically no noise from a USB connection either, end of story.

author: EEVblog
author_rank: Unknown
timestamp: August 10, 2015, 01:40:16 am
content: Quote from: NeverDie on August 09, 2015, 10:17:48 pm

author: Fungus
author_rank: Super Contributor
timestamp: August 10, 2015, 02:09:12 am
content: Quote from: NeverDie on August 09, 2015, 10:55:01 pmThe datasheet has a very detailed chapter on power consumption.

author: NeverDie
author_rank: Regular Contributor
timestamp: August 10, 2015, 03:45:09 am
content: Quote from: Fungus on August 10, 2015, 02:09:12 amTrue, but it turns out to be very hard to know if you actually have a genuine Nordic Semiconductor NRF24L01+ chip on your module or instead have one of many different counterfeit chips that are being passed off as genuine, when they're not. In some circles there's growing consensus that if you purchased your modules on Ebay or through AliExpress or similar, you very likely received counterfeit chips--and generally you can't tell by their appearance alone which are fake and which are not:http://hackaday.com/2015/02/23/nordic-nrf24l01-real-vs-fake/In a perfect world, though, you're right: I wouldn't need to do this measurement, I could just look at the datasheet. I'll grant you that.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 10, 2015, 03:46:23 am
content: Quote from: NeverDie on August 09, 2015, 11:45:23 pmBetter in what sense? You're trading signal strength (volts for a given current flow) for noise (noise floor of the scope, stray noise from the radio, other circuits and surroundings), and for no advantage:For a given change in supply voltage deltaV, the change in power draw will almost certainly be less than deltaI = 2*deltaV*Io.Which for VCC = 5V and Io = 100mA (just WAGs here), means your ~50mV signal shown above is making a 1% difference in supply, and maybe a 1% difference in current, or out of 500mW load, 2% or 10mW. Which is a tiny amount, probably less than your combined resistor tolerance plus measurement error.You always want to use the largest shunt you can get away with, given limitations on peak current demand, desired accuracy, acceptable power dissipation and so on.Tim

author: EEVblog
author_rank: Unknown
timestamp: August 10, 2015, 07:00:36 am
content: I just did a video answering this question, as I see it a lot. Rendering now.

author: vk6zgo
author_rank: Super Contributor
timestamp: August 10, 2015, 10:11:17 am
content: Once upon a time,Oscilloscopes did not haveanyway of changing the volts/div setting to match a probe,so if you used a "X10" probe.the displayed voltage would be a tenth of that which the user might expect.At that time,however,Engineers & Technicians were equipped with a very useful accessory,called "a functioning brain".Using this amazing device,they were able to multiply the reading by 10in their heads,& had very little difficulty in using X1,X10,or even X100 probes.This was obviously an unsatisfactory state of affairs,so 'scope manufacurers devised probes which told the Oscilloscope to multiply the reading so the user didn't need to!This brought about confusion,as people persisted in using the old style probes,& having switched off their brain,started to get confused,as they expected the Oscilloscope to do their thinking for them!

author: EEVblog
author_rank: Unknown
timestamp: August 10, 2015, 10:32:53 am
content: Quote from: vk6zgo on August 10, 2015, 10:11:17 am*snort*

author: tautech
author_rank: Super Contributor
timestamp: August 10, 2015, 11:03:53 am
content: Quote from: vk6zgo on August 10, 2015, 10:11:17 am+1And many that acquire CRO's as their first scope quickly learn this is the case and many threads here attest to this fact. That some also have this affliction with a DSO that does all the work for them I also find amusing.But we have all done it ourselves in our early days, those that haven't are liars or have bad memory.I still find myself counting graticules and portions of.A reminant of times past I guess.

author: mcinque
author_rank: Unknown
timestamp: August 10, 2015, 11:19:51 am
content: Quote from: NeverDie on August 09, 2015, 10:17:48 pmDon't be offended, but it seems like you're never touched the manual of the scope you've bought. Not even with a 6ft pole.As a suggestion, it's always good to read carefully every manual of every instrument you own. This not to avoid asking advices, but to really understand your instruments and what you can do (and most important what youcan notdo) with them. I'm talking about safety for example.Quote from: NeverDie on August 09, 2015, 10:17:48 pmHmmm... why? If you're working with arduinos, I guess you debug logic levels (TTL, I2C, PWM etc), so why you should need 1mV/div?

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: August 10, 2015, 12:10:03 pm
content: Quote from: NeverDie on August 09, 2015, 10:55:01 pmFor this sort of thing, use avaraging or high-res acquisition mode, whatever it's called on your scope - on lower rate timebase settings it avarages multiple samples to produce each sample point. (not trace-to-trace avaraging, though for regular waveforms this can also sometimes be useful)Also use bandwidth limiting on the input.Bear in mind that at high sensitivites, the length of the probe ground wire can be a major issue, so you need to ground at the tip ring, or just use a length of coax with short ends soldered across the resistor instead of the probe

author: NeverDie
author_rank: Regular Contributor
timestamp: August 10, 2015, 02:42:29 pm
content: Quote from: EEVblog on August 10, 2015, 07:00:36 amI just now saw the new video you made. Fantastic! A+ Thanks!

author: Howardlong
author_rank: Super Contributor
timestamp: August 10, 2015, 02:51:37 pm
content: Quote from: vk6zgo on August 10, 2015, 10:11:17 am+10. (or is it +1 or maybe it's +100, not sure, I need to refer to some online help).Pretty sure many old farts like me still regularly still do so when using non-readout probes on older scopes, or indeed scopes without any probe readout facility or probe correction. Pretty sure they sent men to the moon without much in the way of probe correction too.

author: dom0
author_rank: Super Contributor
timestamp: August 10, 2015, 04:24:44 pm
content: Quote from: Howardlong on August 10, 2015, 02:51:37 pmDepends on the appreciation attenuation factor.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: August 10, 2015, 04:27:14 pm
content: I've seen people who have only used DSOs actually not even be able to calculate a frequency of a regular signal on their DSOs by using the graticule grid and timebase settings. Nor can they read a voltage value off the trace. They depend on "numbers in boxes" for their data, and use the "Auto" button far more than they should be doing.But that's really beside the point of this thread, I think. DSOs vs CROs... well, I'd say one should either learn the basics of scoposcopy using a CRO, or pretend that your DSO is an analog scope until you understand how to read the traces directly using the graticule and the horiz. and vert. settings. Use of the "Auto" button should be forbidden entirely until the fledgling scoposcopist can read frequencies and voltages from the trace alone, then rarely used afterwards.On the Rigol 1054Z you can make a noisy trace look a lot "Better", that is, thinner, by using the Average acquire mode and choosing a suitable number of averages. You can also turn down the Display intensity.And as others have pointed out, using a 1x probe (with the correct probe attenuation setting in the Channel menu of course!) is rarely appropriate and has problems of its own.

author: vk6zgo
author_rank: Super Contributor
timestamp: August 11, 2015, 02:58:30 am
content: Quote from: tautech on August 10, 2015, 11:03:53 amWith the old style CROs,any confusion was usually only for a few minutes,as commonsense asserted itself(or the Boss slapped you over the ear!).The first thing you did if you got a "funny" display amplitude was to look at "Cal Out" on the 'scope.If that was wrong,too,suspicion went straight to the probe.Of course,switchable 1X/10X probes were pretty much unknown in those days!Rigol,obviously meant well in making the X!/X10 function switchable on the 'scope,but they may have been better to have left the "volts/div" unchanged.Alternatively,they could have included "X10" or a distinctive colour in the "volts/div" display,or lit up an LED alongside the BNC input for whichever channel is selected as "X10".Unfortunately,people see more expensive 'scopes with automatic "volts/div" switching from the probe,& naturally assume their cheaper unit has it as well.I don't really like the Rigol display,with so many parameters shown on screen.It seems "cluttered",with no parameter seemingly given any priority .Of course,this is from screenshots---using it in "real life" may be very different,as you quickly learn to ignore what isn't of immediate concern.

author: rs20
author_rank: Super Contributor
timestamp: August 11, 2015, 04:32:35 am
content: Quote from: vk6zgo on August 11, 2015, 02:58:30 am+1, this is really good advice. The very moment you're confused about what's going on on your oscilloscope screen, move the probe over to the compensation/cal posts. The worst mistake you can make is to assume that your test equipment is perfect and/or omnipotent.If the OP had done this, the question would have instead been "why is my oscilloscope reading 50V p-p on a 5V p-p input?", and it's possible with such a strong hint he/she may have figured it out without asking the question!

author: fivefish
author_rank: Frequent Contributor
timestamp: August 11, 2015, 04:40:57 am
content: On a related 1X/10X note... My scope is currently at Rigol (Oregon) being repaired.The 10X readings are correct.But my 1X readings are 0.16Volts short for every volt of input.So I don't think it's a simple multiplication factor being done in software?For a whole week, me and Rigol engineer were going back and forth with me telling him there is a problem with my scope, and showing him proof/screenshots. And him reporting the readings he's getting are correct and within tolerance.So today, I said "okay, if you can't find problem, just ship it back... btw, what are the readings on 1X settings?"A few minutes later He came back with "It failed at 1X. That was a surprise. Not sure we have seen that before but we'll get it repaired"

author: rs20
author_rank: Super Contributor
timestamp: August 11, 2015, 10:25:22 am
content: Quote from: fivefish on August 11, 2015, 04:40:57 amYou're not describing the problem properly. Is the problem when thesoftwareis set to 1x, or when theprobeis set to 1x? I'd be astonished if changing the software settings did anything other than just modifying the on-screen voltage annotations and readouts, it shouldn't do anything to the trace.

author: fivefish
author_rank: Frequent Contributor
timestamp: August 11, 2015, 02:53:04 pm
content: Quote from: rs20 on August 11, 2015, 10:25:22 amWhen the scope/software is set to software 1X, my 1054 scope is showing wrong voltage readings, both on the vertical trace and the Measurement stats.I'd be astonished if changing the software settings did anything other than just modifying the on-screen voltage annotations and readouts, it shouldn't do anything to the trace.Well, join the club... Rigol engineer was surprised too and emailed me back"That was a surprise. Not sure we have seen that before but we'll get it repaired"Update: just want to add, only my CH 1 is affected by this software 1X accuracy problem.... if it's software I would think all my channels should have been affected on my unit, but CH2, 3, 4 shows the correct voltage readings at software 1X setting. So maybe some hardware in my CH 1 (voltage reference maybe) was the problem. I'll know more when Rigol ships the unit back to me.

author: rs20
author_rank: Super Contributor
timestamp: August 11, 2015, 08:18:48 pm
content: Quote from: fivefish on August 11, 2015, 02:53:04 pmDidn't answer my simple "Is it A or B" question!! So you didn't try setting only the probe to 1x, leaving the oscilloscope at 10x? And you didn't try setting the probe to 10x, and switching only the oscilloscope to 1x?Also, did you try swapping probes around to see if the problem was attached to the scope channel or the probe?

author: fivefish
author_rank: Frequent Contributor
timestamp: August 11, 2015, 08:46:39 pm
content: And you can't understand what I posted? My scope at 1x setting is giving wrong voltage measurements. I'm not even using a probe. Straight BNC and alligator clips connected to power supply. Seems like a hardware problem with Channel 1, 1x setting on my scope.At 10x setting (which the Rigol engineer was using to replicate my problem), it was giving him correct voltage measurements. So he's at a loss for explanation either. -- that's why it took us so long to really pin down the exact problem. Because initially he can't duplicate the problem I'm reporting. Only when I told him to try it at the 1X did he see the problem.QuoteDidn't matter. Scope was giving wrong answers at 1X. Rigol thinks it's a hardware problem. They're fixing it right now.