Can Your DSO Do This?  - Page 1
Forum section: electronics / testgear

author: alsetalokin4017
author_rank: Super Contributor
timestamp: February 08, 2016, 12:52:26 pm
content: Vertical mode triggering, allowing stable display of two (or maybe more) unrelated waveforms with different frequencies.....I can't see any way to do it on the Rigol DS1054Z for example. Yet even the basic analog Tek 2213a does a good job of it. I don't think I've seen this mentioned in the various "DSO vs CRO" discussions, and I can't remember if the high end LeCroy and Tek DSOs that I used to use at work could do it.

author: vk6zgo
author_rank: Super Contributor
timestamp: February 08, 2016, 12:58:19 pm
content: If I recall correctly,W2AEW covered this with a couple of Youtube videos.You have to save the display with a DSO to get a similar display,although it doesn't feel as satisfying to me.

author: Mechatrommer
author_rank: Super Contributor
timestamp: February 08, 2016, 01:02:42 pm
content: some modern dso cost $800 a pop, lets just assume thats the norm price nowadays. but some, with the same cost you can get 2 pops, not just you will get 2 FFT albeit slower 16K FFT, 2 decoders etc, but the good thing is, you also will have 2 unrelated trigger circuit, non-to-be-found in any modern dso at the priceits just you need to make a custom rig to stack them together for minimum footprint, even without, still less than the cro's of the yesteryears.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: February 08, 2016, 01:14:08 pm
content: Quote from: vk6zgo on February 08, 2016, 12:58:19 pmYeah, definitely not as satisfying since the saved trace will not be live.

author: Ata
author_rank: Contributor
timestamp: February 08, 2016, 01:57:10 pm
content: Yes.... My DS1102E can do this... Just set the alternate trigger mode, then you can set the horizontal time division and trigger level/type independently on each channel.. simultaneously.My DS1104Z can't do this because this and my other DSO scopes do not have alternate trigger modes.It seems that on modern DSO tes alternate trigger mode has been eliminated..

author: rf-loop
author_rank: Super Contributor
timestamp: February 08, 2016, 03:54:30 pm
content: Quote from: alsetalokin4017 on February 08, 2016, 12:52:26 pmOf course can.Here scope is running and trigger mode ALT. CH1 signal is just sine wave ~270kHz and CH2 signal is ~977kHz frequency sine and AM modulated with ~1kHz and this channel is set for trig this AM modulation freq. (of course without ext trig sync)Both channels have separate trigger settings. Trigger result is rock solid.Bottom window can see both sinewaves (and CH2 there is this carrier ^977.2kHz)Here also trigger ALT. Both channels have separate own trigger. There is two different frequency and different lenght pulses. Here also measurements on + tracking cursors. (here was also tested wfm/s speed. Result, 18kwfm/s)

author: Mechatrommer
author_rank: Super Contributor
timestamp: February 08, 2016, 04:09:51 pm
content: Quote from: rf-loop on February 08, 2016, 03:54:30 pmso thats what ALT is for? this makes me a total newbie. i didnt know i can do that on my DS1052E

author: xygor
author_rank: Regular Contributor
timestamp: February 08, 2016, 04:38:30 pm
content: Quote from: alsetalokin4017 on February 08, 2016, 12:52:26 pmThat doesn't look like a good job of it. Trigger instability? Focus?

author: xygor
author_rank: Regular Contributor
timestamp: February 08, 2016, 04:40:12 pm
content: Quote from: rf-loop on February 08, 2016, 03:54:30 pmSo what model is it?

author: rf-loop
author_rank: Super Contributor
timestamp: February 08, 2016, 05:12:04 pm
content: Quote from: xygor on February 08, 2016, 04:40:12 pmXDS3102A

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: February 08, 2016, 06:11:58 pm
content: Quote from: alsetalokin4017 on February 08, 2016, 12:52:26 pmAlternate trigger is pretty rare on DSOs, and the few that have it are pretty much all entry-level scopes. It's a nice feature but I can't see much need for it, which is probably why it has died out in the first place.

author: Fungus
author_rank: Super Contributor
timestamp: February 08, 2016, 06:13:10 pm
content: Quote from: Wuerstchenhund on February 08, 2016, 06:11:58 pmDoes the R&S HMO1202 have it?

author: rf-loop
author_rank: Super Contributor
timestamp: February 08, 2016, 06:32:49 pm
content: Quote from: Wuerstchenhund on February 08, 2016, 06:11:58 pmI need it very often.Are these examples of entry level scopes: Keysight, InfiniiVision 3000X, 4000XOr is this comment something like this:Fox says he does not want rowan berries, they are acidic. Bird says that of course we want rowan berries. they are a great delicacy.

author: Gyro
author_rank: Super Contributor
timestamp: February 08, 2016, 06:52:53 pm
content: The humble Owon VDS series have it too.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: February 08, 2016, 07:06:32 pm
content: Quote from: rf-loop on February 08, 2016, 06:32:49 pmWhat for (just curious)?QuoteThe DSOX3k is an upper entry-level scope, the DSOX4k is a lower mid-range scope.Why?QuoteAnd your point is?

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: February 08, 2016, 07:19:08 pm
content: Quote from: Fungus on February 08, 2016, 06:13:10 pmFind out yourself:https://cdn.rohde-schwarz.com/pws/dl_downloads/dl_common_library/dl_brochures_and_datasheets/pdf_1/service_support_30/HMO1X02_bro-en_3607-0152-32_v0200_72dpi.pdf

author: Muxr
author_rank: Super Contributor
timestamp: February 08, 2016, 07:34:37 pm
content: I do not think HMOs have it. RTM has the B Trigger, but I didn't see it in the HMO user manual.

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: February 08, 2016, 08:01:33 pm
content: Quote from: Muxr on February 08, 2016, 07:34:37 pmAt least the HMO723..2024 have a so called B trigger. But this is a trigger on the same channel. Like 1st edge is rising edge at 0.5V, 2nd edge is either at 2V within 100ns.Not useful for the dual triggering discussed here.

author: Muxr
author_rank: Super Contributor
timestamp: February 08, 2016, 08:07:45 pm
content: Quote from: 0xdeadbeef on February 08, 2016, 08:01:33 pmInteresting, the RTM has the source setting under B trigger, where you can pick the channel. I guess HMO doesn't have that ability.

author: xygor
author_rank: Regular Contributor
timestamp: February 08, 2016, 09:03:09 pm
content: Even on the (older) RTM1054, isn't B trigger just the second in a sequence? Either channel can be picked for trig B, but neither channel is triggered until trig A is followed by trig B, then both are triggered simultaneously. Is my understanding wrong? Is latest RTM different?

author: Muxr
author_rank: Super Contributor
timestamp: February 08, 2016, 10:16:11 pm
content: Quote from: xygor on February 08, 2016, 09:03:09 pmI think you might be right, I will have to look into it.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: February 09, 2016, 03:15:29 am
content: Quote from: xygor on February 08, 2016, 04:38:30 pmHandheld camera and slow shutter speed. Here's a better photo using a tripod.But it appears that some lower-end DSOs can do this after all. The Owon is impressive, I would not have expected that.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: February 09, 2016, 03:21:11 am
content: Ok..... how about this?(In this case the Rigol DS1054Z makes a pretty good effort...)

author: C
author_rank: Super Contributor
timestamp: February 09, 2016, 05:38:18 am
content: Analog scopesALT & CHOPPED modesWhy have them, Most scope CRT's only have one electron beam so only one spot screen can be created at a time.Chopped is a fast switch between inputs while horizontal sweep happens.ALT is one input for each hormonal sweep.Working with just one beam is foundation for a lot of analog scope modes.Digital scopes have no limits like this for display.The limit in a digital scope is how many ADC's and how many channels.One ADC and two channels: you have to time switch between channels.Two ADCs and Two channels: you can have same time samples which is important for some things.

author: tautech
author_rank: Super Contributor
timestamp: February 09, 2016, 06:43:50 am
content: Quote from: C on February 09, 2016, 05:38:18 amBut we're discussing Alt channel triggering, completely different to Alt trace display modes.

author: nctnico
author_rank: Super Contributor
timestamp: February 09, 2016, 04:00:08 pm
content: On a DSO an alt triggering mode is of very little use because the signals will need to be sampled independantly which make the 2 traces unrelated in time. IOW: you won't be able to see how a single glitch on channel 1 affects the signal showed in channel 2. The strong point of a DSO is that all channes are sampled synchronously and each channel shows the result from the same circumstances (the signals have a perfect time relation).I do have to note that I have heard about certain (older) Tektronix DSOs which using alternate sampling so they can show unrelated signals as well.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: February 09, 2016, 05:22:13 pm
content: Quote from: nctnico on February 09, 2016, 04:00:08 pmI'm still not sure what the real-world value of Alt Trigger is. Usually when looking at multiple signals at once they are all time-related in some way (which is usually the reason why you'd want to have them together on the screen in the first place).I'd be curious in which situations Alt Trg was of value. My guess is that there aren't many.

author: nctnico
author_rank: Super Contributor
timestamp: February 09, 2016, 05:30:43 pm
content: I can imagine it may be handy to have 2 time unrelated signals stable on screen for some tests.BTW: On the Tektronix scopes I mention earlier the alternate sampling had the unwanted side effect that timing relation between signals wasn't there which confused the hell out of unsuspected users especially since this wasn't documenten. Free_electron knows more details since he brought it up a long time ago.

author: CustomEngineerer
author_rank: Frequent Contributor
timestamp: February 10, 2016, 02:29:01 am
content: When I first purchased a scope I made the mistake of getting the Hantek MSO5102D. It had an "Alternative Trigger" that allowed you to alternate triggering off of channels 1 & 2. I played around with the Alternative Trigger a bit but ended up returning the scope because of constant lock ups. I ended up getting a Rigol DS2072A instead. When I first got the Rigol I was a little disappointed that it didn't have an equivalent trigger type, but I have yet to run into a situation where I actually need it.

author: vk6zgo
author_rank: Super Contributor
timestamp: February 10, 2016, 03:58:46 am
content: Quote from: Wuerstchenhund on February 09, 2016, 05:22:13 pmI've never had occasion to use it.All the possibilities I try to think of all fail the "why would you need to do that" test.

author: Smokey
author_rank: Super Contributor
timestamp: February 10, 2016, 04:48:41 am
content: Didn't single shot mode and deep memory on DSOs effectively make all this obsolete?

author: alsetalokin4017
author_rank: Super Contributor
timestamp: February 10, 2016, 05:50:13 am
content: Why build it in to an analog (or digital) scope if it's not useful?Just because you or I can't think of situations where it would be useful, doesn't mean that there aren't any. And those situations must come up often enough so that even a "beginner" 2-trace analog scope like the Tek 2213 series had Vertical Mode triggering designed in.

author: vk6zgo
author_rank: Super Contributor
timestamp: February 10, 2016, 06:15:54 am
content: I was thinking,perhaps to look at a gated signal,where that signal isn't synched to the gating frequency.One case would be a Morse Code letter keying an RF carrier.Attack & decay time of the envelope may do strange things to the first few cycles of the RF envelope,which would be interesting to know,as they would indicate if the RF cycle was likely to produce spurii.Another,I guess,would be plain old AM,where you might want took at phase changes in the RF with modulation.I'm not sure that either would be that easy to do,& there are other ways to look at them.For instance,with Morse keying,as long as the envelops shape is OK,the generation of spurii is minimised.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: February 10, 2016, 06:23:02 am
content: Quote from: alsetalokin4017 on February 10, 2016, 05:50:13 amWho knows, maybe because technology back then was different than it is today, and with that the type of signal that most engineers had to deal with. Today digital stuff is almost everywhere and in digital systems signals are usually time-related, which often wasn't the case in analog systems.QuoteWhich is exactly the reason why I asked for any real-life examples...

author: Smokey
author_rank: Super Contributor
timestamp: February 10, 2016, 06:34:50 am
content: Quote from: Wuerstchenhund on February 10, 2016, 06:23:02 amGives people something to talk about on the internet...

author: miguelvp
author_rank: Super Contributor
timestamp: February 10, 2016, 06:37:11 am
content: Couldn't the DS2000 and DS1000z do that with the Delay trigger type?

author: vk6zgo
author_rank: Super Contributor
timestamp: February 10, 2016, 06:49:19 am
content: Analog TV was all time related,(except the actual RF channels in most places except France,where they locked the vision & sound carriers to line syncs).As I did a lot of my "scoping" on TV related stuff,I didn't need to use this function.

author: markone
author_rank: Frequent Contributor
timestamp: February 10, 2016, 01:58:46 pm
content: My spanking new GDS-2072E does :

author: nctnico
author_rank: Super Contributor
timestamp: February 10, 2016, 02:20:24 pm
content: Cool! I have seen the alternate option on mine as well but until now had no clue what is was for but I'll admit I did not bother to look it up in the manual. Let's give it a try with 4 channels...

author: Fungus
author_rank: Super Contributor
timestamp: February 10, 2016, 02:38:27 pm
content: Quote from: Smokey on February 10, 2016, 04:48:41 amNope. Simultaneously watching two different signals with low frequency modulators isawesome(dude!)

author: C
author_rank: Super Contributor
timestamp: February 10, 2016, 05:03:30 pm
content: OscilloscopeQuoteIf you use the same probe to look at a reference signal and then switch the probe to look at a second signal, the differences you see will be the signal differences.The Oscilloscope does not even have to be in calibration for this.A smart user of the scope would use the UN-cal Volts/div knob & the UN-cal sweep time knob to set the reference signal to be an easy to look at and check on the display.Having more than one channel and or scope that you can use, just reduces the number of setting changes needed.Some adjustments can effect more than one signal. Having more inputs saves time if you have to adjust a signal that also effects a previous signal in some way.A system that uses many matching signal channels each with many test points per channel that have to be correct.A simple case is a 14 channel reel to reel tape recorder. A nice one where you have separate record and playback heads. After you have one recorder working, you then need to get the ability to swap tapes between recorders.With just 8 recorders that is 112 signals to match up per test point.The tape heads do wear which causes signal changes. So for a final result you want record input= tape = playback output.For those of you who have worked with something like this, add two little things.Reduce the designed recording speed by 1/2 and switch to very thin tape with out losing needed BW.14" glass reels with I think it was 6000 feet of tape.The recorders I am thinking of were $200,000 in the early 1970's before the changes needed for 1/2 speed and thin tape. One of a pair was always running 24x360, with the 360 often increased.

author: Bryan
author_rank: Frequent Contributor
timestamp: February 11, 2016, 02:17:15 am
content: My older DS1052E has alternate triggering. Surprised the newer DS1047 doesn't

author: alsetalokin4017
author_rank: Super Contributor
timestamp: February 11, 2016, 02:56:58 am
content: Quote from: miguelvp on February 10, 2016, 06:37:11 amNot as far as I can tell. If you can get a 1000z to do it, please post your technique and results.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: February 11, 2016, 02:59:43 am
content: Quote from: C on February 10, 2016, 05:03:30 pmWhat? How is this relevant to the present question, which involves displaying two or more frequencies stably at the same time?

author: alsetalokin4017
author_rank: Super Contributor
timestamp: February 11, 2016, 03:02:43 am
content: Quote from: nctnico on February 10, 2016, 02:20:24 pmThat looks great! Now I'm _really_ jealous...

author: miguelvp
author_rank: Super Contributor
timestamp: February 11, 2016, 03:40:44 am
content: Quote from: alsetalokin4017 on February 11, 2016, 02:56:58 amNot too stable and only had a little play with it. I don't have a DS1000z but it also has Delay trigger.But as I said, sometimes it looses lock, but didn't play with all of the comparison types and values.I used the same frequencies as markone's first image. 1MHz and 775KHz and this is the result on my DS2000 series:Note: looking at the DS1000z programmer manual, the Trigger type Delay only works with two signals as well, so no alt on 4 channels, sorry. But you can choose two of all four channels.Edit: But it's tricky to get the right Time value to get both channels in sync.Edit2: maybe the less than greater than, or greater than less than will work best, they have an upper and lower time limit.

author: miguelvp
author_rank: Super Contributor
timestamp: February 11, 2016, 04:49:01 am
content: Explanation of the Delay Type options on the DS1000z (Edit, it should be similar for the DS2000) according to the programmer reference manual (after correcting some minor misspellings):> GREater: trigger when the time difference (Delta T) between the specified edges of trigger source A and trigger source B is greater than the preset time limit.< LESS: trigger when the time difference (Delta T) between the specified edges of trigger source A and trigger source B is lower than the preset time limit.>< GLESs: trigger when the time difference (Delta T) between the specified edges of trigger source A and trigger source B is greater than the lower limit of the preset time and lower than the upper limit of the preset time. Note that the time lower limit must be lower than the time upper limit.<> GOUT: trigger when the time difference (Delta T) between the specified edges of trigger source A and trigger source B is lower than the lower limit of the preset time or greater than the upper limit of the preset time. Note that the time lower limit must be lower than the time upper limit.I think I got the symbols rightEdit: left the sweep on Auto and didn't change the holdoff value, maybe those can help too.Also this is more cumbersome than just pressing the ALT button or CHOP like I have on my two Tek scopes and I can get 4 channels on those.But I really never had the need to do an ALT because then you don't see the signal in relation to the other signal.At least the Delay Trigger puts them in relation with each other, which might be more useful.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: February 11, 2016, 08:51:10 am
content: Well... shiver me timbers, it worked! Thanks, friends. The first times I tried it I didn't have faith, I guess, because I couldn't get it to work. But with the knowledge that it _could_ be done, I was able to get the settings right (for similar frequencies as used above).ETA: I think I've got the hang of it now... Thanks again!

author: miguelvp
author_rank: Super Contributor
timestamp: February 11, 2016, 08:59:55 am
content: Now try with not being on STOP mode, it should work too

author: alsetalokin4017
author_rank: Super Contributor
timestamp: February 11, 2016, 09:01:16 am
content: Quote from: miguelvp on February 11, 2016, 08:59:55 amOf course, I just use "STOP" so that saves to the USB will go faster. It's not necessary to have the scope Stopped to have the stable signals, but it sure does make screensaves a lot faster, especially when there are lots of things going on in the display.

author: miguelvp
author_rank: Super Contributor
timestamp: February 11, 2016, 09:15:00 am
content: Well, you are welcome, actually I wouldn't have looked for multiple triggers if you didn't post in the forum.I did recall seeing the delay trigger in the past but never really needed it for anything.It's more cumbersome as I mentioned before, but at least it gives you a true representation of the relations of both waves instead of just triggering without correlation.Not sure if that adds value or not.

author: glicos
author_rank: Regular Contributor
timestamp: February 11, 2016, 02:31:10 pm
content: Tried it on DSO4102C. It has Swap (Alter) Trigger option

author: Alfons
author_rank: Regular Contributor
timestamp: February 11, 2016, 04:21:18 pm
content: Here a picture without "Stop".