Yet another "Help me choose oscillospe thread"

[luisr]

Hello everyone,

yep another one 
I was reluctant to post this thread but after searching through the forum and seeing horrible things like the siglent SDS1202X-E issue I don't want to screw my purchase

I'll be using the scope for hobby/learning purposes which includes but not limited to: learning SPI,I2C and maybe FlexRay... also observing rise/fall time of GPIO pins on the plethora of SBC/dev boards I have (some of them run up to 1Ghz processor clock aka raspberry pi 3... others just ~400Mhz)

Which bandwidth I need? obviously I don't know so I'm aiming at highest I can get 100-200Mhz within a ~$650 initial budget, without having to hack the unit and only buying it from USA (Amazon or any distributor willing to ship to a freight forwarder)

So far it looks like my best bet is to go with Keysight DSOX1102A (upgradable to 100Mhz, only two channels but really good real-time sampling at 1Gsa/S with all channels enabled?) or go with Rigol DS1104Z Plus (100Mhz, 4 channels, less real sampling than Keysight one but more memory and upgradable with logic analyzer?)

I also found some good deals on Rigol DS2102E ($650, two channel) and GW Instek GDS-2072E I found on amazon listed at $400 (this looks too good to be true since it's listed as 100Mhz while manufacturer page list it as 70Mhz  )

Now I said that DSOX1102A is my best bet because even though the 4 channel Rigol might be a better option in terms of number of channels, I'm concerned by the EEVblog #683 jitter issue and the fact real time sampling gets down to 250Msa/s which unless I didn't understood is not good for 70Mhz?

Thanks in advance for any advice you can provide
kind regards

Edited: I fixed Rigol models and added some concerns

[tautech]

Hello everyone,

yep another one 
I was reluctant to post this thread but after searching through the forum and seeing horrible things like the siglent SDS1202X-E issue I don't want to screw my purchase

Nothing horrible about SDS1202X-E just ensure you get one with BB or higher in the SN#.

[nctnico]

The GW Instek GDS2702E is 70MHz indeed but it does have mature firmware. I don't think you need a lot of bandwidth to look at GPIO pins because you will be controlling them from software so any activity will be in microsecond timescales.

[rstofer]

Did you read any of the threads around here?  The most often recommended scope for beginners at this point is the Rigol DS1054Z which, when unlocked, provides 100 MHz bandwidth plus decoding of SPI, Serial and I2C.  It has 4 channels which is ideal for SPI.  Not required, necessarily, but ideal.

The Siglent SDS1204X-E is newly released to the US.  The 100 MHz incantation is only slightly interesting because it competes head-to-head with the Rigol DS1054Z and the Rigol is pretty mature at this point.  The Siglent if probably going to turn out to be the better scope at some point but I'll wait...

The 200 MHz version is very interesting because more bandwidth is always better.  Unfortunately, it is priced at $759 and that pretty much cools my interest because I have the DS1054Z and a Tek 485.  There is a comprehensive review in this forum.  A VERY comprehensive review.  The thing is, it is all text with no video and, frankly, I have no idea what most of it means.  For a lot of it, I don't know if I'm even supposed to care!  I'm waiting for a video review comparing the Rigol on the right with the Siglent on the left.  Side-by-side through all the features.

http://www.saelig.com/product/sds1204x-e.htm

There are several scopes in the low price range but you won't get more bang for the buck than with the Rigol.  Not that you can't get a better UI or a better FFT but you need to pay a lot more to get it.

Fulfilled by Amazon:

https://www.amazon.com/Rigol-DS1054Z-Digital-Oscilloscopes-Bandwidth/dp/B012938E76

[luisr]

that was quick 

Nothing horrible about SDS1202X-E just ensure you get one with BB or higher in the SN#.

Nice, I read about the resistor fix so my guest is Siglent fixed the issue in new units? I'll write an email to Saelig to see if they have any problem shipping to my freight forwarder... thx for the info

The GW Instek GDS2702E is 70MHz indeed but it does have mature firmware. I don't think you need a lot of bandwidth to look at GPIO pins because you will be controlling them from software so any activity will be in microsecond timescales.

That scope is listed on Amazon as a 100Mhz scope with a 57% discount (original List price is way higher then manufacturer's MSRP though)
here is the link if you are interested https://www.amazon.com/GW-Instek-GDS-2102E-Oscilloscope-Technology/dp/B00W7YX4B4/ref=sr_1_5?s=industrial&ie=UTF8&qid=1513388634&sr=1-5&keywords=GW+Instek+GDS-2072E

Did you read any of the threads around here? 

  Not as much as I should but yes, in fact that's why I said I was reluctant to post the question... and by this: https://www.eevblog.com/forum/testgear/newbies-please-read-before-posting/

I'm aware of the venerable DS1054Z, but I didn't include it because it's a 50Mhz stock, and I just realized I forgot to mention a very important thing: I don't want to hack the unit... So I really appreciate your comment and updated my original post as a result.

also on that matter, and the reason I included the DS1104Z Plus, is because according to this post: https://www.eevblog.com/forum/testgear/rigol-ds1054z-ds1074z-or-ds1104z/ the three scope share same hardware (thought the plus can be upgraded)

BTW Yeah, the SDS1204X-E looks really interesting, and AFAIK it was not affected by the compensation issue because the resistors mentioned on the fix where already populated on the 4 channel models?
I can just hold the purchase couple of month more and save the couple of hundred more and get that one...

Anyway, thx all for anwsering..

[tautech]

that was quick 

Nothing horrible about SDS1202X-E just ensure you get one with BB or higher in the SN#.

Nice, I read about the resistor fix so my guest is Siglent fixed the issue in new units? I'll write an email to Saelig to see if they have any problem shipping to my freight forwarder... thx for the info

The GW Instek GDS2702E is 70MHz indeed but it does have mature firmware. I don't think you need a lot of bandwidth to look at GPIO pins because you will be controlling them from software so any activity will be in microsecond timescales.

That scope is listed on Amazon as a 100Mhz scope with a 57% discount (original List price is way higher then manufacturer's MSRP though)
here is the link if you are interested https://www.amazon.com/GW-Instek-GDS-2102E-Oscilloscope-Technology/dp/B00W7YX4B4/ref=sr_1_5?s=industrial&ie=UTF8&qid=1513388634&sr=1-5&keywords=GW+Instek+GDS-2072E

Did you read any of the threads around here? 

  Not as much as I should but yes, in fact that's why I said I was reluctant to post the question... and by this: https://www.eevblog.com/forum/testgear/newbies-please-read-before-posting/

I'm aware of the venerable DS1054Z, but I didn't include it because it's a 50Mhz stock, and I just realized I forgot to mention a very important thing: I don't want to hack the unit... So I really appreciate your comment and updated my original post as a result.

also on that matter, and the reason I included the DS1104Z Plus, is because according to this post: https://www.eevblog.com/forum/testgear/rigol-ds1054z-ds1074z-or-ds1104z/ the three scope share same hardware (thought the plus can be upgraded)

BTW Yeah, the SDS1204X-E looks really interesting, and AFAIK it was not affected by the compensation issue because the resistors mentioned on the fix where already populated on the 4 channel models?
I can just hold the purchase couple of month more and save the couple of hundred more and get that one...

Anyway, thx all for anwsering..

Just to be clear resistors of any kind were not the issue, it was a 4 pF 1202 SMD 500V cap in part of the analog input stage for SDS1202X-E that was needed to properly compensate 10x probe over all V/div ranges.
The SDS1*04X-E models are not at all affected.
Check this review in progress for info on 2 and 4ch X-E models:
https://www.eevblog.com/forum/testgear/siglent-sds1104x-e-in-depth-review/

[rstofer]

I'm aware of the venerable DS1054Z, but I didn't include it because it's a 50Mhz stock, and I just realized I forgot to mention a very important thing: I don't want to hack the unit... So I really appreciate your comment and updated my original post as a resu

Your choice of course!  You should know, it isn't really a hack.  It involves looking up a different secret squirrel code and entering it into the scope.  I would venture to say that every owner on this forum has already done this.  There is simply no downside and if Rigol was concerned about it, they would have changed the code a couple of years ago.  As it is, they absolutely own the entry level scope market.

I am just guessing but I'll bet the upgrade of the Siglent SDS1x04X-E from 100 to 200 MHz is done the same way.  It's just that I haven't seen a process for determining the proper secret squirrel code.

It makes all the sense in the world for the manufacturers to have a firmware upgradable design.  It costs essentially nothing and reduces manufacturing costs.  And yes, the Rigol really IS a 100 MHz scope.  They all are!  It's just a switch setting.  Dave has done a video describing how the analog front in has two different low pass filter selections.

That new Siglent looks awfully interesting.  I know I'm going to talk myself into buying one.

[luisr]

Just to be clear resistors of any kind were not the issue, it was a 4 pF 1202 SMD 500V cap in part of the analog input stage for SDS1202X-E that was needed to properly compensate 10x probe over all V/div ranges.
The SDS1*04X-E models are not at all affected.
Check this review in progress for info on 2 and 4ch X-E models:
https://www.eevblog.com/forum/testgear/siglent-sds1104x-e-in-depth-review/

I stand corrected...

About the review, very in-depth indeed, but my mind was already away from the Siglent and so I didn't read the whole thing... just gave a quick lok at bandwidth section... unfortunately for me I'm on same boat as RSTOFER, I saw the review but do not fully understand it... 

I found couple of quick reviews for the SDS1204X-E  like this one

From your signature I take you're an New Zealand Siglent dsitributor, or am I wrong?

As Dave commented about Siglent support joining the forum, it's quite nice to see manufacturers and distributors on this kind of forum so we can have good information and quick responses like yours...

...

It makes all the sense in the world for the manufacturers to have a firmware upgradable design.  It costs essentially nothing and reduces manufacturing costs.  And yes, the Rigol really IS a 100 MHz scope.  They all are!  It's just a switch setting.  Dave has done a video describing how the analog front in has two different low pass filter selections.

That new Siglent looks awfully interesting.  I know I'm going to talk myself into buying one.

I agree on the firmware upgradable design, bummer that lowest keysight DSOX2000 model is so damn expensive... then again if they sell a fully capable 300Mhz, 4CH 2Gsa/s scope but firmware to bare bones and the we "software upgrade" it for free... it would be a big ROI loss for the company (as probably have been stated on other post)

I might take the Siglent SDS1204X-E into consideration unle

Kind Regards

[tautech]

Just to be clear resistors of any kind were not the issue, it was a 4 pF 1202 SMD 500V cap in part of the analog input stage for SDS1202X-E that was needed to properly compensate 10x probe over all V/div ranges.
The SDS1*04X-E models are not at all affected.
Check this review in progress for info on 2 and 4ch X-E models:
https://www.eevblog.com/forum/testgear/siglent-sds1104x-e-in-depth-review/

I stand corrected...

About the review, very in-depth indeed, but my mind was already away from the Siglent and so I didn't read the whole thing... just gave a quick lok at bandwidth section... unfortunately for me I'm on same boat as RSTOFER, I saw the review but do not fully understand it... 


From your signature I take you're an New Zealand Siglent dsitributor, or am I wrong?

As Dave commented about Siglent support joining the forum, it's quite nice to see manufacturers and distributors on this kind of forum so we can have good information and quick responses like yours...

Correct, my details are on the Siglent webpage:
http://www.siglent.com/ENs/lxwms.aspx?id=616

There's quite a few distributors on the forum and representing many brands.
We each have something to offer be it help from the manufacturer, bug reports or just general usage advice/guidance.

IMO your more advanced/higher BW requirements should steer you towards at least a 200 MHz DSO but your budget might need lifting.

How do you get on for getting equipment where you are ?

[Old Printer]

Luisr, curious as to what is behind your reluctance to hack a scope. In the entry level market the manufactures all but openly condone it. It really has be come a selling trick/marketing ploy. It's not like lifting coins from the poor box at church it is easy to reverse in case of the need to send the scope in for waerentee work. Rigol is now giving all but the bandwidth options away for free anyway. They seem to go out of their waY to make it easy, when it would be easy for them to make it hard. Think about it.

[luisr]

Correct, my details are on the Siglent webpage:
http://www.siglent.com/ENs/lxwms.aspx?id=616

There's quite a few distributors on the forum and representing many brands.
We each have something to offer be it help from the manufacturer, bug reports or just general usage advice/guidance.

IMO your more advanced/higher BW requirements should steer you towards at least a 200 MHz DSO but your budget might need lifting.

How do you get on for getting equipment where you are ?

Nice,

Not sure if I have high requirements since as I say I'm just a hobbyist wanting to learn, so my selection is based around getting the best I can around the budget I've got...

as for getting the equipment, I normally buy it from Amazon, Digilent, etc an send it to a freight forwarder which in turn bring it to where I am (taking care of any Import paperwork)

Luisr, curious as to what is behind your reluctance to hack a scope. In the entry level market the manufactures all but openly condone it. It really has be come a selling trick/marketing ploy. It's not like lifting coins from the poor box at church it is easy to reverse in case of the need to send the scope in for waerentee work. Rigol is now giving all but the bandwidth options away for free anyway. They seem to go out of their waY to make it easy, when it would be easy for them to make it hard. Think about it.

because I want to minimize the chances of having to send the unit back for repair since it will be more expensive for me to do so, I had a bad previous experience while hacking a TL-WR1043ND router which I almost rendered unusable because I flashed a openwrt firmware that enabled the write protect flag on the unit's flash memory    and though at the end I managed to recover it and it was a good learning experience... I do not want to risk my scope   

Kind Regards

[tautech]

Correct, my details are on the Siglent webpage:
http://www.siglent.com/ENs/lxwms.aspx?id=616

There's quite a few distributors on the forum and representing many brands.
We each have something to offer be it help from the manufacturer, bug reports or just general usage advice/guidance.

IMO your more advanced/higher BW requirements should steer you towards at least a 200 MHz DSO but your budget might need lifting.

How do you get on for getting equipment where you are ?

Nice,

Not sure if I have high requirements since as I say I'm just a hobbyist wanting to learn, so my selection is based around getting the best I can around the budget I've got...

as for getting the equipment, I normally buy it from Amazon, Digilent, etc an send it to a freight forwarder which in turn bring it to where I am (taking care of any Import paperwork)

Then you might consider buying direct from Siglent America's Amazon shop.
They are a member here too and you can be sure of top class support should you need it.
They trade under the handle of Siglent Technologies on Amazon:
https://www.amazon.com/Siglent-Technologies/b/ref=bl_dp_s_web_9126325011?ie=UTF8&node=9126325011&field-lbr_brands_browse-bin=Siglent+Technologies

They list the SDS1104X-E as temp out of stock and there's not a listing up yet for SDS1204X-E but send them an email or PM them through the forum.
Here's their coverage area FYI:
https://www.siglentamerica.com/how-to-buy/

[tggzzz]

I'll be using the scope for hobby/learning purposes which includes but not limited to: learning SPI,I2C and maybe FlexRay... also observing rise/fall time of GPIO pins on the plethora of SBC/dev boards I have (some of them run up to 1Ghz processor clock aka raspberry pi 3... others just ~400Mhz)

OK; that's a sensible starting point.

You probably have three requirements in there:

• observing rise/fall times of digital signals that are (or can be made to be) repetitive. This requires raw bandwidth. Modern digital logic (e.g. 74lvc1g*) has sub-nanosecond risetimes, but most SBCs are unlikely to be that fast. My preference would be a 300MHz or faster scope with a "low impedance" "Z0" "resistive divider" probe. Those probes are the only ones that can be easily made at home At these speeds probing technique is vital
• capturing various waveforms on digital interfaces, but are you really interested in volts-vs-time of those signals?
• decoding the information being transmitted over those interfaces.

A good strategy is to use a scope to ensure signal integrity, then to flip to using digital tools when debugging in the digital domain.  By digital tools I mean logic analysers plus protocol decoders, and thoughtfully applied good old simple printf() statements.

Thus you might like to consider getting a secondhand old working >300MHz scope, plus a very cheap logic analyser. You would be surprised what you can achieve with those, given thought imagination skill and some time.

Bear in mind that the more complex the test instruments, the longer the learning curve, the more you'll say "what's it doing now?", and probably the more bugs.

[Fungus]

I'll be using the scope for hobby/learning purposes which includes but not limited to: learning SPI,I2C and maybe FlexRay... also observing rise/fall time of GPIO pins on the plethora of SBC/dev boards I have (some of them run up to 1Ghz processor clock aka raspberry pi 3... others just ~400Mhz)

That right there screams "200MHz".

...Rigol DS1104Z Plus

That would be a terrible choice. The $350 DS1054Z can be unlocked to all options (including 100MHz bandwidth) just by pressing the right sequence of buttons on the front panel. You can also relock it if you want and nobody will ever know.

Also the logic Rigol logic analyzer is very limited compared to something PC-based with mouse/keyboard.

I'm concerned by the EEVblog #683 jitter issue and the fact real time sampling gets down to 250Msa/s which unless I didn't understood is not good for 70Mhz?

That's fixed by firmware a long time ago. Anything left is just Rigol haters (there's a lot of them around here, most of them also happen to sell Siglent gear, go figure!). None of them has ever demonstrated that the 'jitter' thing has any effect at all on the function.

I'll be using the scope for hobby/learning purposes which includes but not limited to: learning SPI,I2C and maybe FlexRay... also observing rise/fall time of GPIO pins on the plethora of SBC/dev boards I have (some of them run up to 1Ghz processor clock aka raspberry pi 3... others just ~400Mhz)

This requires raw bandwidth.

Thus you might like to consider getting a secondhand old working >300MHz scope.

Yep. There's no way you can get enough bandwidth in a new DSO on your budget plus an old analog 'scope is maybe the best gadget for looking at pure rise times, etc.

PS: Do you really need to look at that or is it just curiosity?

[tggzzz]

I'll be using the scope for hobby/learning purposes which includes but not limited to: learning SPI,I2C and maybe FlexRay... also observing rise/fall time of GPIO pins on the plethora of SBC/dev boards I have (some of them run up to 1Ghz processor clock aka raspberry pi 3... others just ~400Mhz)

This requires raw bandwidth.

Thus you might like to consider getting a secondhand old working >300MHz scope.

Yep. There's no way you can get enough bandwidth in a new DSO on your budget plus an old analog 'scope is maybe the best gadget for looking at pure rise times, etc.

PS: Do you really need to look at that or is it just curiosity?

Checking signal integrity is like checking the PSU rails. If either are deficient then you can expect to get all sorts of intermittent strange results, and end up fruitlessly fiddling with the wrong things.

[luisr]

Then you might consider buying direct from Siglent America's Amazon shop.
They are a member here too and you can be sure of top class support should you need it.
They trade under the handle of Siglent Technologies on Amazon:
https://www.amazon.com/Siglent-Technologies/b/ref=bl_dp_s_web_9126325011?ie=UTF8&node=9126325011&field-lbr_brands_browse-bin=Siglent+Technologies

They list the SDS1104X-E as temp out of stock and there's not a listing up yet for SDS1204X-E but send them an email or PM them through the forum.
Here's their coverage area FYI:
https://www.siglentamerica.com/how-to-buy/

Again thanks for the info, this will be really handy in case I decide to go with a Siglent model... might be I can persuade them to give a EEVBlog member discount?  we'll see

I'll be using the scope for hobby/learning purposes which includes but not limited to: learning SPI,I2C and maybe FlexRay... also observing rise/fall time of GPIO pins on the plethora of SBC/dev boards I have (some of them run up to 1Ghz processor clock aka raspberry pi 3... others just ~400Mhz)

OK; that's a sensible starting point.

You probably have three requirements in there:

• observing rise/fall times of digital signals that are (or can be made to be) repetitive. This requires raw bandwidth. Modern digital logic (e.g. 74lvc1g*) has sub-nanosecond risetimes, but most SBCs are unlikely to be that fast. My preference would be a 300MHz or faster scope with a "low impedance" "Z0" "resistive divider" probe. Those probes are the only ones that can be easily made at home At these speeds probing technique is vital
• capturing various waveforms on digital interfaces, but are you really interested in volts-vs-time of those signals?
• decoding the information being transmitted over those interfaces.

A good strategy is to use a scope to ensure signal integrity, then to flip to using digital tools when debugging in the digital domain.  By digital tools I mean logic analysers plus protocol decoders, and thoughtfully applied good old simple printf() statements.

Thus you might like to consider getting a secondhand old working >300MHz scope, plus a very cheap logic analyser. You would be surprised what you can achieve with those, given thought imagination skill and some time.

Bear in mind that the more complex the test instruments, the longer the learning curve, the more you'll say "what's it doing now?", and probably the more bugs.

I have explored that route, buying a good old high bandwidth scope... but don't have much space on my "bench", an option might be putting it perpendicular with screen facing up at a convenient height/elevation ?.... but I think I prefer a compat DSO... also I need to consider weight and size since it surely will cost a lot more to bring one of those where I live 

Regarding the fast IO pins, I haven't tried myself but looks like the processor used in the Raspberry PI is able to connect one of its internal clock generator to one GPIO port... in fact there is a guy who has a firmware that claims a range from 130 kHz to 250 MHz... and I sure i can use assembly code to directly control a GPIO through its register which should give better results than trying to do it in C... anyway, this is why I want the scope for...

I'm planning to add some logic analyzer down the road.... so yeah, scope is more for "seeing" what's going on with the signal...

@blueskull: Well, if it is that easy then i might consider a model that allows me to "upgrade it" to 300Mhz model.... might be one of the Rigol DS2000E family?
can you share some info on that matter (granted it would not get you or me in trouble that is  )

...Rigol DS1104Z Plus

That would be a terrible choice. The $350 DS1054Z can be unlocked to all options (including 100MHz bandwidth) just by pressing the right sequence of buttons on the front panel. You can also relock it if you want and nobody will ever know.

Also the logic Rigol logic analyzer is very limited compared to something PC-based with mouse/keyboard.

I was thinking it would be handy to be able to have the logic analyzer integrated on the scope which i can do down the by just buying the option for the Rigol

PS: Do you really need to look at that or is it just curiosity?

TBH, just curiosity... so far i've been using spice simulation and Proteus(ISIS) simulation demo which have a really nice scope simulator but since it's a demo I won't allow me to save anything 

Anyway, so this is what I'm planning so far

bandwidth: 200Mhz or higher (might be hacking a lower model is is easy enough and manufacturer doesn't care, and by that I mean that its been openly discussed here and manufacturer does care to take action)
Sampling Rate: no less than 500Msa/s when all channels active
# Channels: go with 2Ch (since 4Ch might be well out of my budget when taking into account sampling rate
Capture memory: not sure here, the more the better I guess

So, I'm back to https://www.eevblog.com/forum/testgear/digital-oscilloscope-comparison-chart/

[Fungus]

Also the logic Rigol logic analyzer is very limited compared to something PC-based with mouse/keyboard.

I was thinking it would be handy to be able to have the logic analyzer integrated on the scope which i can do down the by just buying the option for the Rigol

It's definitely handy, but you're assuming it's a good logic analyzer. 

(nb. The logic probes cost 300 bucks and for that price you can get a Saleae...)

PS: Do you really need to look at that or is it just curiosity?

TBH, just curiosity...

 

It could be expensive just to see that though.

# Channels: go with 2Ch (since 4Ch might be well out of my budget when taking into account sampling rate
Capture memory: not sure here, the more the better I guess

The new 200Mhz, 4-channel Siglent can do 500Msa/s on two channels, although:
a) It's very new production (they forgot some capacitors in last month's batch!)
b) Nobody's even started listing all the firmware bugs yet
c) Firmware updates to fix things are an unknown quantity, Siglent doesn't have a stellar record in this department.

[Old Printer]

bandwidth: 200Mhz or higher (might be hacking a lower model is is easy enough and manufacturer doesn't care, and by that I mean that its been openly discussed here and manufacturer does care to take action)
Sampling Rate: no less than 500Msa/s when all channels active
# Channels: go with 2Ch (since 4Ch might be well out of my budget when taking into account sampling rate
Capture memory: not sure here, the more the better I guess

So, I'm back to https://www.eevblog.com/forum/testgear/digital-oscilloscope-comparison-chart/

My comments on hacking were stated to be aimed at the entry level scopes, 1054Z in particular. From what I have read, admittedly not too much as they are out of my interest area, the higher cost/performance models are not necessarily as easy or approvingly hacked. These models are aimed more at business/corporate purchasers with deeper pockets and are used in environments where hacking is just not a good business model.

[Fungus]

My comments on hacking were stated to be aimed at the entry level scopes, 1054Z in particular. From what I have read, admittedly not too much as they are out of my interest area, the higher cost/performance models are not necessarily as easy or approvingly hacked.

Yes, the DS1054Z is the only 'scope that's trivial to unlock. All the others require at least opening it up and using a JTAG programmer to modify some flash memory.

[nctnico]

# Channels: go with 2Ch (since 4Ch might be well out of my budget when taking into account sampling rate
Capture memory: not sure here, the more the better I guess

Given you want to use it for microcontroller circuits I'd go for 4 channels. Two channels isn't going to be enough.
BTW One scope missing from your list is the MicSig TO1104. It has some advantages over the DS1054Z, it has mature firmware and it isn't too expensive. I wrote a review earlier this year:
https://www.eevblog.com/forum/testgear/micsig-to1104-(similar-to-rigol-1104z)/msg1196293/#msg1196293
The firmware version in this review didn't have the final version of the decoding software yet but that has been available for a couple of months.

[rstofer]

Bandwidth is everything - except channels...

When you throw out numbers like 400 MHz and I assume you mean square waves, the required bandwidth gets well beyond affordable.

Look at the video above at around 14:00.  The author is trying to display a lowly 100 MHz square wave on a 200 MHz scope.  All he gets is a sine wave!  And that's the right answer!

A square wave is the sum of all the odd harmonics of the fundamental from DC to daylight with diminishing amplitudes.  Fourier Series comes in about here.

What that means is that the next odd harmonic for a 100 MHz square wave (the 3rd) is at 300 MHz and well beyond the bandwidth of a 200 MHz scope.  The trace won't even square up until the 9th harmonic or so.  If this is the case, a 100 MHz square wave needs a 1 GHz scope.  A 400 MHz square wave won't look particularly square unless the scope has about a 4 GHz bandwidth.  Just getting to the 3rd harmonic (the first one above the fundamental) takes about 1.2 GHz of bandwidth.

In rough numbers, a 200 MHz scope can be expected to show a decent display of a 20 MHz signal.  A 100 MHz scope only a 10 MHz signal.

https://www.mathworks.com/help/matlab/examples/square-wave-from-sine-waves.html

It's important to be realistic about signal frequency and scope bandwidth.

[tggzzz]

I'll be using the scope for hobby/learning purposes which includes but not limited to: learning SPI,I2C and maybe FlexRay... also observing rise/fall time of GPIO pins on the plethora of SBC/dev boards I have (some of them run up to 1Ghz processor clock aka raspberry pi 3... others just ~400Mhz)

OK; that's a sensible starting point.

You probably have three requirements in there:

• observing rise/fall times of digital signals that are (or can be made to be) repetitive. This requires raw bandwidth. Modern digital logic (e.g. 74lvc1g*) has sub-nanosecond risetimes, but most SBCs are unlikely to be that fast. My preference would be a 300MHz or faster scope with a "low impedance" "Z0" "resistive divider" probe. Those probes are the only ones that can be easily made at home At these speeds probing technique is vital
• capturing various waveforms on digital interfaces, but are you really interested in volts-vs-time of those signals?
• decoding the information being transmitted over those interfaces.

A good strategy is to use a scope to ensure signal integrity, then to flip to using digital tools when debugging in the digital domain.  By digital tools I mean logic analysers plus protocol decoders, and thoughtfully applied good old simple printf() statements.

Thus you might like to consider getting a secondhand old working >300MHz scope, plus a very cheap logic analyser. You would be surprised what you can achieve with those, given thought imagination skill and some time.

Bear in mind that the more complex the test instruments, the longer the learning curve, the more you'll say "what's it doing now?", and probably the more bugs.

I have explored that route, buying a good old high bandwidth scope... but don't have much space on my "bench", an option might be putting it perpendicular with screen facing up at a convenient height/elevation ?.... but I think I prefer a compat DSO... also I need to consider weight and size since it surely will cost a lot more to bring one of those where I live 

Those are indeed a disadvantage in your case, but a Tek 475/485 or even a 2465 can be used vertically on the floor. It helps if you are short

Regarding the fast IO pins, I haven't tried myself but looks like the processor used in the Raspberry PI is able to connect one of its internal clock generator to one GPIO port... in fact there is a guy who has a firmware that claims a range from 130 kHz to 250 MHz... and I sure i can use assembly code to directly control a GPIO through its register which should give better results than trying to do it in C... anyway, this is why I want the scope for...

The signal integrity will be the same for a 130kHz and a 250MHz digital signal - or for a 1mHz signal. The only important feature is the transition time!

I was thinking it would be handy to be able to have the logic analyzer integrated on the scope which i can do down the by just buying the option for the Rigol

That relies on the logic analyser "seeing" the same signals as the UUT, e.g. threshold, clocking interval etc. If you have a scope "deciding" how to interpret the analogue signal as a digital signal, that introduces more uncertainty.

ISTR that some scopes will only decode what's visible on the screen, not everything that is captured in their memory. That would significantly reduce their usefulness in many situations.

In my experience the three critical features of a LA are clock speed, arm/trigger/filter, and memory depth. Better arm/trigger/filter means the memory doesn't have to be so deep. Ideally the LA's clock input will be driven by the UUT's clock.

[luisr]

My comments on hacking were stated to be aimed at the entry level scopes, 1054Z in particular. From what I have read, admittedly not too much as they are out of my interest area, the higher cost/performance models are not necessarily as easy or approvingly hacked.

Yes, the DS1054Z is the only 'scope that's trivial to unlock. All the others require at least opening it up and using a JTAG programmer to modify some flash memory.

I have a JLink EDU adapter and have done some jtag stuff (in fact I had a nice debug experience with a weird LPC4370 https://www.eevblog.com/forum/microcontrollers/did-i-damaged-one-of-my-lpc4370-or-is-this-a-siliconmarking-error/msg389440/#msg389440)

# Channels: go with 2Ch (since 4Ch might be well out of my budget when taking into account sampling rate
Capture memory: not sure here, the more the better I guess

Given you want to use it for microcontroller circuits I'd go for 4 channels. Two channels isn't going to be enough.
BTW One scope missing from your list is the MicSig TO1104. It has some advantages over the DS1054Z, it has mature firmware and it isn't too expensive. I wrote a review earlier this year:
https://www.eevblog.com/forum/testgear/micsig-to1104-(similar-to-rigol-1104z)/msg1196293/#msg1196293
The firmware version in this review didn't have the final version of the decoding software yet but that has been available for a couple of months.

Thx, gotta give that a look

Bandwidth is everything - except channels...

When you throw out numbers like 400 MHz and I assume you mean square waves, the required bandwidth gets well beyond affordable.

Look at the video above at around 14:00.  The author is trying to display a lowly 100 MHz square wave on a 200 MHz scope.  All he gets is a sine wave!  And that's the right answer!

A square wave is the sum of all the odd harmonics of the fundamental from DC to daylight with diminishing amplitudes.  Fourier Series comes in about here.

What that means is that the next odd harmonic for a 100 MHz square wave (the 3rd) is at 300 MHz and well beyond the bandwidth of a 200 MHz scope.  The trace won't even square up until the 9th harmonic or so.  If this is the case, a 100 MHz square wave needs a 1 GHz scope.  A 400 MHz square wave won't look particularly square unless the scope has about a 4 GHz bandwidth.  Just getting to the 3rd harmonic (the first one above the fundamental) takes about 1.2 GHz of bandwidth.

In rough numbers, a 200 MHz scope can be expected to show a decent display of a 20 MHz signal.  A 100 MHz scope only a 10 MHz signal.

https://www.mathworks.com/help/matlab/examples/square-wave-from-sine-waves.html

It's important to be realistic about signal frequency and scope bandwidth.

 

Sorry if that was not clear, when I say 400Mhz I mean processor speed... not measuring signal at that high frequency cause for that I will need to sell the apartment (and probably will be short on cash) to buy some serious gear

So I think I'll be fine with a 200Mhz scope

@tggzz

ISTR that some scopes will only decode what's visible on the screen, not everything that is captured in their memory. That would significantly reduce their usefulness in many situations.

In my experience the three critical features of a LA are clock speed, arm/trigger/filter, and memory depth. Better arm/trigger/filter means the memory doesn't have to be so deep. Ideally the LA's clock input will be driven by the UUT's clock.

If that the case then I will concentrate this budget on a good scope and later acquire a good logic analyzer, or? maybe I can go the hack route save couple of hundreds buck for the LA? That depends on what I end up buying

Thx all

[rstofer]

Those are indeed a disadvantage in your case, but a Tek 475/485 or even a 2465 can be used vertically on the floor. It helps if you are short

My 485 has always stood upright on the floor.  It is simply too deep to fit my bench.  A 350 MHz 485 is a pretty nice scope and I only paid about $200 for mine some 12 years ago.

Dave has done a video talking about mixed signal scopes.  As I recall, he would rather have a separate logic analyzer. 

On the subject of LAs, it is important that it have the ability to accept an external state clock.  This is useful for analyzing state machines where the only instant signals are important is just before the state clock.  One t_setup ahead.  What you really want to know is what the logic decided was the next state.  Sampling this with a clock internal to the LA is a waste of time (pun, such as it was, intended).

Yes, I wanted SPI decoding (primarily) but my bit rates are in the low MHz range and I'm not decoding "War and Peace".  I only need to verify a few characters in decoding and the rest of the time I am going to look at the timing of the various signals to compare against the datasheet for the peripheral.  I need to verify CPHA and CPOL plus the fact that I don't raise CS' too soon after sending the last char to the serializer.  I need to wait for it to clear...

I bought the DS1054Z because I thought it would be handy to show all 4 signals concurrently.  It is...  If I need bandwidth, the 485 is the scope to use, not the Rigol.  But the 485 doesn't make any measurements at all!  Not even frequency.  In comparison to the Rigol, it is very limited in features.  Other than bandwidth.

[nctnico]

Dave has done a video talking about mixed signal scopes.  As I recall, he would rather have a separate logic analyzer. 

Unfortunately Dave forgot that being able to see digital signals change in realtime (which logic analysers can't do!) can be very helpfull. I like to have an MSO on my bench besides a logic analyser. Also an MSO is a much simpler tool to use and it can do 90% of the logic analyser tasks.

[tggzzz]

@tggzz

ISTR that some scopes will only decode what's visible on the screen, not everything that is captured in their memory. That would significantly reduce their usefulness in many situations.

In my experience the three critical features of a LA are clock speed, arm/trigger/filter, and memory depth. Better arm/trigger/filter means the memory doesn't have to be so deep. Ideally the LA's clock input will be driven by the UUT's clock.

If that the case then I will concentrate this budget on a good scope and later acquire a good logic analyzer, or? maybe I can go the hack route save couple of hundreds buck for the LA? That depends on what I end up buying

I am willing to suggest "ways of thinking" and possible alternatives. I am not willing to offer guidance as to what you should do since only you know all your objectives and tradeoffs.

Unless you already have suitable tools and already know how to use them, it usually pays dividends to consider the details of how you would go about making the measurements with the simplest possible tools plus a thoughtful implementation strategy.

Consider, for example, how you might use a very cheap LA ($10-20) which is little more than a clock plus memory. You would probably want to generate a signal saying "this is interesting", capture that plus the data, and then write your own software to post-process the captured data streams to extract only the "interesting" samples.

Or you might have software inside you UUT that blips an output when it detects a significant event, e.g. receipt or generation of a particular message.

In particular, learn to think in terms of FSMs where events cause transitions between states, and code your systems so that there is a direct representation of the states and events. Then use printf() statements and/or blip outputs when events or states or events-when-in-a-single-state occur.

And to annoy rstofer, I'll note my Tek 485 cost £25, but I did have to diagnose and recap the PSU That's my principal scope on a very small bench, or vertically alongside it. N.B.: I don't recommend you get a broken scope, unless fixing it is an end in itself!

[CustomEngineerer]

My comments on hacking were stated to be aimed at the entry level scopes, 1054Z in particular. From what I have read, admittedly not too much as they are out of my interest area, the higher cost/performance models are not necessarily as easy or approvingly hacked.

Rigol has never given any indication they either care or are concerned about the hacking of any of their scopes (or their other equipment that's also easily unlockable) regadless of cost/performance.

Yes, the DS1054Z is the only 'scope that's trivial to unlock. All the others require at least opening it up and using a JTAG programmer to modify some flash memory.

Sorry, but this is not true. The DS2000A series is as easily hackable as the DS1000Z. No JTAG, no opening scope, no modifying flash required. Also, like on the DS1000Z series, removing the hack (which leaves it completely undectable that it was ever used) is as easy as connecting to the scope through telnet, and sending a single command to reset the options to the default status.

Anyway, so this is what I'm planning so far

bandwidth: 200Mhz or higher (might be hacking a lower model is is easy enough and manufacturer doesn't care, and by that I mean that its been openly discussed here and manufacturer does care to take action)
Sampling Rate: no less than 500Msa/s when all channels active
# Channels: go with 2Ch (since 4Ch might be well out of my budget when taking into account sampling rate
Capture memory: not sure here, the more the better I guess

I'm not necessarily recommending the DS2000A scope, but it does seem to meet your new requirements. The DS2072A can be unlocked to 300MHz, has 1Gsa/s with both channels active and 56M capture memory. And unlike the DS1000Z it does decodes on the full sample memory, not just what's on screen. It's only 2 channel, but it's at least worth a look.

[luisr]

I'm not necessarily recommending the DS2000A scope, but it does seem to meet your new requirements. The DS2072A can be unlocked to 300MHz, has 1Gsa/s with both channels active and 56M capture memory. And unlike the DS1000Z it does decodes on the full sample memory, not just what's on screen. It's only 2 channel, but it's at least worth a look.

Yep, the Rigol DS2072A looks like a winner at this point... but I will have to dig more into the hacking thing.

[nctnico]

I'm not necessarily recommending the DS2000A scope, but it does seem to meet your new requirements. The DS2072A can be unlocked to 300MHz, has 1Gsa/s with both channels active and 56M capture memory. And unlike the DS1000Z it does decodes on the full sample memory, not just what's on screen. It's only 2 channel, but it's at least worth a look.

Is this recommendation from your own experience? AFAIK there are still quite a few unresolved issues in the firmware.