Author Topic: eevBLAB #5 - Are Mixed Signal (MSO) Oscilloscopes Worth The Money?  (Read 18413 times)

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Offline EEVblog

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Re: eevBLAB #5 - Are Mixed Signal (MSO) Oscilloscopes Worth The Money?
« Reply #25 on: January 19, 2015, 01:05:00 pm »
As for the other poster who said "This is probably long enough to be a full EEVblog episode, and I agree.  The 15-20 min episodes are often quite useful; and I don't really think it's worth splitting the blabs out, they've been good watching so far.

The problem is one of a production difference between a blab video and a regular video. Blab videos are designed to be a zero thought, grab camera, press record, one take, upload.
They are designed to be quick and efficient, and expectations of them are low.
On the other hand once a decide to do a regular video, I go into regular video mode and start to think about stuff to include, experiments, demos, and extra tangent information that is appropriate etc. And a shoot it in an entirely different with dozens and dozens of different shorter clips.
It essentially takes all day to shoot and edit and muck around with even the simplest one of those.
And for a simple question like this I wanted to answer, if I decided to make it into a regular video it most likely wouldn't have because:
a) I didn't have enough time that day, and I hate shooting stuff over multiple days and avoid it wherever possible.
b) It would have screwed up my timeline because I would have to finish it today (Monday) so I probably would have done it in lieu of a Mailbag (yet again)

So I hope that gives some insight into how and why I shoot certain video. It was likely either a quick blab, or it was nothing.
 

Offline open loop

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Re: eevBLAB #5 - Are Mixed Signal (MSO) Oscilloscopes Worth The Money?
« Reply #26 on: January 19, 2015, 07:39:43 pm »
Thanks Dave for the video  :-+

This is what I was asking myself exactly a couple of months ago and actually had a play with a couple of Rigol scopes at the Rigol vendor in my area. One was the MSO2000 series and the other was an MSO1074z. And I came to exactly the same conclusion that Dave did, if you really need the MSO capability then sure go spend the extra money. Otherwise use the extra few hundred $ to get a decent USB based LA.

One thing I did notice (as was pointed out to me) was that the LA probes of the MSO2000 were far better than the ones used on the MSO1074z. Not that the MSO1000z probes were bad as they are great for ocasional use.

I think that these days it is more important to have serial decoding and a JTAG tool to hand.
 

Offline alank2

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Re: eevBLAB #5 - Are Mixed Signal (MSO) Oscilloscopes Worth The Money?
« Reply #27 on: January 20, 2015, 12:44:13 am »
There were tons of false transitions shown on the traces that did not exist in reality, and that prevented me from using it at all.
What's the current state of affairs in this regard? Are there any inexpensive logic analyzers with the shielded coaxial probes? This is usually not listed in the specs, and it is hard to tell from the product photos.

It can be a problem, one that can be mitigated by having a configurable threshold and also more grounds, best is one per channel.  Another technique might be to ground channels and use a signal channel every other channel.

Setting a proper threshold can eliminate a lot of noise.  LogicPort does this very well by having a variable threshold you can adjust.  Others like the Saleae allow you to set the threshold for the logic you are using such as 3.3 or 5, etc., but know that sometimes what they might give you for 5v is not a true 2.5v threshold, but something different.  This is where it is worth digging into the specifications a bit.

Having more grounds, hopefully one per signal near the signal is really ideal.  The newer Saleae's have a ground for each channel for example.

You can ground unused channels so they aren't floating and toggling which could eat up your buffer memory if compression is used.

Honestly this was a problem for me initially with LA's to the point where I questioned how useful they could actually be, but I found the issue was the cheap models I was using.  In the end I ended up with a Saleae Logic16 and also a Intronix LogicPort and have found that this isn't a problem on either one of these if I have it configured right.
 

Offline SteveyG

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Re: eevBLAB #5 - Are Mixed Signal (MSO) Oscilloscopes Worth The Money?
« Reply #28 on: January 20, 2015, 12:47:35 am »
Thanks for taking the time to make a video on my question  :-+ It's an interesting discussion, which a lot of people will have a different opinion on. For me, the Rigol opens the question to potentially a different array of answers because of the price point - It's probably the only scope where you pay twice as much for the LA option. Buying the Keysight 2 or 3000 it's almost a no brainer to opt for the LA option.

The trigger output is something I'd not considered, so very useful tip!
« Last Edit: January 20, 2015, 12:55:44 am by SteveyG »
 

Offline alank2

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Re: eevBLAB #5 - Are Mixed Signal (MSO) Oscilloscopes Worth The Money?
« Reply #29 on: January 20, 2015, 01:02:07 am »
I also think one more thing comes into this discussion and that is the way a scope is meant to trigger - over and over again on a repeating signal.  I found this not intuitive when it comes to trying to "analyze" logic signals.  Yes, you can set the scope to trigger once.  Yes, you can set the timebase to that everything you want to capture will end of up one screen.  Yes, with deep enough memory you can zoom into the places where you want to see what happened.

One thing that was mentioned with the Rigol's specifically is that it decodes what is on the screen - so if you scroll the screen in such a way as to push off the first few bits of some serial being decoded, it will decode wrong.  That is an issue that Rigol should fix especially given the price point they charge for their decoders.  I think they should decode from the beginning of the stream to the end and then let you scroll around without affecting the decoding...
 

Offline kevinpt

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Better triggering
« Reply #30 on: January 20, 2015, 05:06:29 am »
You missed that dedicated LAs have much better triggering options than the MSOs. The primitive pattern trigger in them is often not enough for capturing exactly what you need in a complex sequence.
 

Offline Howardlong

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Re: eevBLAB #5 - Are Mixed Signal (MSO) Oscilloscopes Worth The Money?
« Reply #31 on: January 20, 2015, 07:04:32 am »
One thing i missed in the blab or teardown /review (or i missed it) no mention of protocol triggering capabilites.

For examlle : trigger on a missing acq in i2c, or trigger on a write of a specific register in 82c , or a soecific address.


Yes, it will do all those things, or at least they are there in the trigger menu. You can also select H/L/X in each bit position in address and data (up to five successive bytes after the address), and whether it's a read, write, or either.

I have only used the trigger on SPI so far, I am not yet convinced that it always triggered: I am not saying it doesn't work, it does, but I never went back to check if it really did consistently trigger. Happy for others to give further insight.

Here's a vid I did this afternoon doing I2C decoding and triggering. The triggering is perfect, the decoding not so much. (The test did decode perfectly on an Agilent 54831D).

Edit: Link here Doh!
« Last Edit: January 20, 2015, 07:14:22 am by Howardlong »
 

Offline Smokey

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Re: eevBLAB #5 - Are Mixed Signal (MSO) Oscilloscopes Worth The Money?
« Reply #32 on: January 20, 2015, 01:21:49 pm »
With the MSO1074Z being double the price of the DS1054Z, how about buying two DS1054Z scopes and time correlating them.  That would give you at least 7 analog channels if you had to go trigger out of one to an analog channel in on the other.  Is there any software that could pull the traces off the scope and display them all on one screen on a PC?  I remeber seeing on another thread that on the Agilent gear you could take a dedicated scope and a dedicated logic analyzer and pull both time correlated data to display together on a PC.  It looks like Rigol software sucks, but that would be a killer stand alone app even.
 

Offline Bzzz

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Re: eevBLAB #5 - Are Mixed Signal (MSO) Oscilloscopes Worth The Money?
« Reply #33 on: January 24, 2015, 11:04:07 am »
Get the 50Mhz.
70MHz doesn't offer much more for the price difference.
And it can be hacked if that's your thing.

Yep, we heard that. Still, I wonder why virtually nobody thinks of it as software piracy. I'm fine with the 100 MHz hack, as this is (afaik) not an upgrade offered by Rigol (yet). So in order to upgrade your DS1054Z to the DS1104Z the official way (including the sticker on the front), you have to sell the physical unit and buy the faster one.
But the triggering and memory stuff IS a paid option, just like upgrading from $knownOS from Starter to Ultimate Edition or whatever. Everything's already there, it just waits for you to put in the correct blargh and tadaa, additional functionality is activated. If you do that the official way you have to pay for it - if you use a keygen, it's free and you're a bad bad software pirate. Now back to Rigol, that sounds like a call to use keygens instead of buying an official upgrade...?
 

Online hammy

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Re: eevBLAB #5 - Are Mixed Signal (MSO) Oscilloscopes Worth The Money?
« Reply #34 on: January 24, 2015, 11:12:17 am »
Rigol products are sold since years with this possibility. Do you ever wondered why?  :palm:
 

Online nctnico

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Re: Better triggering
« Reply #35 on: January 24, 2015, 11:31:16 am »
You missed that dedicated LAs have much better triggering options than the MSOs. The primitive pattern trigger in them is often not enough for capturing exactly what you need in a complex sequence.
OTOH MSOs often have much more memory than dedicated logic analysers (unless you have a really high end model). On an MSO you just capture everything and look at the data. That is usually quicker than setting up a complicated trigger condition. I'm not sure whether the Rigol 1000Z MSO is good value for money but spending a bit more on a proper MSO is money well spend if you are working with programmable logic.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline Lightages

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Re: eevBLAB #5 - Are Mixed Signal (MSO) Oscilloscopes Worth The Money?
« Reply #36 on: January 25, 2015, 07:20:21 am »
With the MSO1074Z being double the price of the DS1054Z, how about buying two DS1054Z scopes and time correlating them.

The way I understand it is that most things are serial protocols with usually no more than 2 to 4 signals lines to read and decode. If you need more channels, it could start getting up to 30 channels and much more if you are doing parallel buss analysis on things like micros and memory or DMA channels. So in this case even an 8 channel analyze and a 4 channel scope hooked together isn't going to do you much. Connecting 2 scopes together is not going to get you more than 7 channels. This is not that much more useful than 4 channels.

The other pain with trying to keep two instruments synced is the analysis after the capture. Sure the captures will correlated at the trigger point. When you try to scan along and look at the whole capture on both instruments you have two screens to look at, and the problem of trying to keep everything lined up the same way on both screens. This is only scratching the surface of the complication of trying to do the analysis after on two different screens. It can be done of course, but very tediously.
 

Online nctnico

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Re: eevBLAB #5 - Are Mixed Signal (MSO) Oscilloscopes Worth The Money?
« Reply #37 on: January 25, 2015, 07:59:32 am »
IMHO there is not much use for many digital channels. Nowadays everything on the outside is serial. If you have 8 digital channels on an oscilloscope (more will just clutter the screen) you can cover most of the logic analyses tasks. I do have an high end Tektronix logic analyser but the digital channels on my oscilloscope are just easier to work with.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline Smokey

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Re: eevBLAB #5 - Are Mixed Signal (MSO) Oscilloscopes Worth The Money?
« Reply #38 on: January 25, 2015, 08:50:49 am »
With the MSO1074Z being double the price of the DS1054Z, how about buying two DS1054Z scopes and time correlating them.

The way I understand it is that most things are serial protocols with usually no more than 2 to 4 signals lines to read and decode. If you need more channels, it could start getting up to 30 channels and much more if you are doing parallel buss analysis on things like micros and memory or DMA channels. So in this case even an 8 channel analyze and a 4 channel scope hooked together isn't going to do you much. Connecting 2 scopes together is not going to get you more than 7 channels. This is not that much more useful than 4 channels.

The other pain with trying to keep two instruments synced is the analysis after the capture. Sure the captures will correlated at the trigger point. When you try to scan along and look at the whole capture on both instruments you have two screens to look at, and the problem of trying to keep everything lined up the same way on both screens. This is only scratching the surface of the complication of trying to do the analysis after on two different screens. It can be done of course, but very tediously.
I was thinking more along the lines of sucking the data out of the scope and into a PC to do the analysis, rather than trying to line up two little scope screens.  But ya, that's one more step.

I also missed that there was no external reference clock input on these scopes.  No real time correlation :(  Gotta get into the thousands of dollars before you get a reference clock input.
 

Offline PioB

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Re: eevBLAB #5 - Are Mixed Signal (MSO) Oscilloscopes Worth The Money?
« Reply #39 on: January 31, 2016, 09:18:36 pm »
One thing i missed in the blab or teardown /review (or i missed it) no mention of protocol triggering capabilites.

For examlle : trigger on a missing acq in i2c, or trigger on a write of a specific register in 82c , or a soecific address.
...
You dont need deep memory for that. You need realtime decoding of the packet and trigger launch.
...
As comparison : the keysight 4000/5000/6000/7000 series have such trigger capability. Sont know about the 2000 or 3000.
...

Did anyone get around to trying this out on a 3000? Or will one still end up also having to buy a USB LA after getting the highly recommended option on the scope for doing longer acquires?

...Buying the Keysight 2 or 3000 it's almost a no brainer to opt for the LA option.

What would the go to USB LAs be nowadays? The saleae pro (8/16 channels), the intronix logic port (34 channels), the dreamsourcelab dslogic (16 channels), the ikalogic scanaplus (9 channels), the digilent analog discovery 2 (16 channels plus 2 DSO, only 3.3 V iiuc) are all on my radar. But then again, ~1500 USD for the LA option on the scope AND an extra unit might be hard(er) to justify.

TL;DR: How useful is the LA option on the Keysight 3000 series and will one still be tempted to get a USB la for longer acquires?
 

Offline blueskull

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Re: eevBLAB #5 - Are Mixed Signal (MSO) Oscilloscopes Worth The Money?
« Reply #40 on: January 31, 2016, 09:23:25 pm »
No, not for me. Whenever I need to decode something it is usually some serial bus, so 4 channel is enough.

When I deal with parallel bus, it usually goes higher than 100MHz, which makes signal integrity a disaster, so I always end up with designing an adapter board and hook it up to an FPGA board.

So far, I've only used the MSO function on my Analog Discovery for a couple of times, and never used it on my MSOX3104A. So why I got a MSOX3104A instead of a DSOX3104A? Well, I got a deal that is even 50%+ cheaper than a new DSOX3104A.
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Offline Howardlong

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Re: eevBLAB #5 - Are Mixed Signal (MSO) Oscilloscopes Worth The Money?
« Reply #41 on: January 31, 2016, 09:51:54 pm »
One thing i missed in the blab or teardown /review (or i missed it) no mention of protocol triggering capabilites.

For examlle : trigger on a missing acq in i2c, or trigger on a write of a specific register in 82c , or a soecific address.
...
You dont need deep memory for that. You need realtime decoding of the packet and trigger launch.
...
As comparison : the keysight 4000/5000/6000/7000 series have such trigger capability. Sont know about the 2000 or 3000.
...

Did anyone get around to trying this out on a 3000? Or will one still end up also having to buy a USB LA after getting the highly recommended option on the scope for doing longer acquires?

...Buying the Keysight 2 or 3000 it's almost a no brainer to opt for the LA option.

What would the go to USB LAs be nowadays? The saleae pro (8/16 channels), the intronix logic port (34 channels), the dreamsourcelab dslogic (16 channels), the ikalogic scanaplus (9 channels), the digilent analog discovery 2 (16 channels plus 2 DSO, only 3.3 V iiuc) are all on my radar. But then again, ~1500 USD for the LA option on the scope AND an extra unit might be hard(er) to justify.

TL;DR: How useful is the LA option on the Keysight 3000 series and will one still be tempted to get a USB la for longer acquires?

Yes, you can trigger on all those things on i2c on the x3000.

Regarding USB LAs, I used to use a LogicPort fairly regularly, but it largely sits in a drawer now as since getting an MSO I've found little need for it. Certainly the early saleaes and other USB LAs with low samplig rates I find to be of limited use: the LogicPort and the Saleae Pros sample at 500Msa/s which is far more useful although now in some circumstances it can be limiting.

The only reason I use the LogicPort now is for the occasional need to debug parallel busses like some LCD panels with controller chips, where 16 bits isn't enough, for everything else I use an MSO.

One exception to all of this is that when travelling, on the journey I use an Analog Discovery extensively for simple logistical reasons. Getting a scope out on your tray table with your laptop and DUT on a plane isn't going to work. On the other hand, if you've already plumbed in your breadboard to the AD and stuffed it all into a small cardboard box, you're good to go, no one will know any different. Just be prepared for more secondary screenings.
 

Offline rs20

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Re: eevBLAB #5 - Are Mixed Signal (MSO) Oscilloscopes Worth The Money?
« Reply #42 on: January 31, 2016, 10:30:41 pm »
It's all well and good saying you can look at a serial bus with a 4 channel scope, but that leaves you very little extra to look at anything else you might want to correlate that SPI bus with.

For example, I recently was messing around with an ADXL345 chip with 4 SPI pins and two interrupts lines. Thus, the fact that I was working with a modern serial protocol didn't change the fact that I needed 6 channels. Just something for people to think about; I'm not sure staring at a serial bus in isolation is often the whole story?
 

Offline Howardlong

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Re: eevBLAB #5 - Are Mixed Signal (MSO) Oscilloscopes Worth The Money?
« Reply #43 on: January 31, 2016, 11:18:56 pm »
If the proof of the pudding is in the eating, personally speaking I would almost always use the LA in an MSO rather than a USB based tool. Most of that is for the triggering capabilities which seem to be very basic on USB LAs. I am sure there will be other opinions though! The Saleae takes a slightly different workflow, in that it stores everything and you examine it after the capture. This is where a big monitor also comes in handy, but it's often not big enough! For an MSO, you tend to set up triggers.

I guess it's similar in software circles to using a log file instead of a debugger when comparing the Saleae way to how you'd use an MSO.
 

Offline System Error Message

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Re: eevBLAB #5 - Are Mixed Signal (MSO) Oscilloscopes Worth The Money?
« Reply #44 on: June 24, 2016, 12:44:05 am »
so what you're saying in the video is if you want a proper logic analyzer get 4 4channel scopes?
 


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