Which oscilloscope for hobbyist?

[CustomEngineerer]

Regarding the AWG on the DS1000Z-S, as an AWG for my purposes it ain't half bad, but having the connectors on the back as well as having to battle through the scope menus to get at it isn't perfect. If I used an AWG every day it would drive my nuts. You can do sweeping of sorts setting a channel on FM while modulating it with a triangle but it's not a perfect solution. I ran pigtails from the back to avoid having to access the rear of the scope all the time. I found that it's a compromise at the end of the day, but mostly about usability than functionality.

Would you mind giving a little more detail on how you fake the sweeping? Sounds like it could be useful in a pinch.

I also did something similar for the generator connectors to avoid having to reach back behind the scope to hook up. I've got the scope a couple of shelves up on my work desk and mounted some bnc chassis mount feed through adaptors at project level on my desk. I keep the 2 generator connectors hooked to those so when I need the generator I can just connect to the ones on the desk. At first I was a little worried that the extra cable length and going through an extra terminal might affect the signal but I have tested it and haven't noticed any problems.

[Howardlong]

I don't know if the DS2000 is the same as the DS1000Z, but try this...

o 1MHz sine
o set the modulation to FM
o modulating frequency 1kHz
o modulate with triangle
o deviation 1MHz

[Wuerstchenhund]

For your aliasing theory, it is absolutely right, so when trying to probe very fast signals, do not use a low sample rate scope. But it has nothing to do with BW, it's only a matter of sampling rate.

I'm sorry but that's nonsense, BW is as much as important as sample rate.

Here's are some screenshots for a quick test done with a 15MHz pulse (50% DC, generated by an Agilent 33522B) probed by a 3GHz 20GSa/s scope (LeCroy WavePro 7300A):

Sampled at full bandwidth with 20GSa/s:




Sampled at 200MHz bandwidth with 20GSa/s:




Sampled at 20MHz bandwidth with 20GSa/s:




It's pretty obvious that the 20MHz shot doesn't resemble the original signal, which is understandable since important frequency components of the original signal are left out, and that even a very high sample rate can't overcome the limitations imposed by a too low analog bandwidth.

Now, just for fun, let's see what impact the sample rate has:

Sampled at 200GS/s (RIS, something like ETS):




Sampled at 20GS/s:




Sampled at 10GS/s:




Sampled at 5GS/s:




Sampled at 2.5GS/s:




Sampled at 1GS/s:




Sampled at 500MS/s:




Sampled at 250MS/s:




Sampled at 100MS/s:




Sampled at 50MS/s:




We can see that the waveform remains valid all the way down to 250MS/s, which considering that the bandwidth necessary for capturing all relevent components of a 15MHz square wave is 120-150MHz, is logical:




So in short, yes, BW does matter, and no, high sample rates are no substitute for bandwidth.

I've used both 1Gsps 100MHz owon sds7102 and 1Gsps 100MHz owon vds3102 for years, and they have no problems probing 20MHz SPI data bus at all.

You've seen something which may or may not resemble what the original signal looks like, and it may even have worked for you, who knows, but that doesn't mean a 100MHz scope will show you all relevant components of a 20MHz pulse.

So I tested OWON VDS3102L with absolute shittiest front end, let's scale up the frequency, 20MHz square wave at 100MHZ BW, 1Gsps. Still, no signal integrity care at all.

I agree with nbritton, that's a really piss-poor waveform, and unless your signal generator actually produces such crap signals then what you see on the scope is completely useless to assess any of the relevant signal parameters. You can get similarly valid results by reading from fish guts.

[Fungus]

I'm sorry but that's nonsense, BW is as much as important as sample rate.

The two should match. If there's a serious mismatch then that's a red flag. You have to wonder who designed the device.

[Fungus]

since many students who will be using the Analog Discovery don’t understand the concept of “-3dB” is the “bandwidth” of an instrument, and that a 1V input signal with -3dB applied will measure 0.707V, it was felt from a marketing standpoint to specify the bandwidth of the analog inputs as less than -0.5dB as the “bandwidth”. This ensures that when connecting a 10MHz signal on a traditional instrument (with much higher bandwidth), and the Analog Discovery, the measurements will be very similar, and lead to less confusion.

Is the the first ever sighting of a manufacturer underselling the bandwidth? 

[Wuerstchenhund]

I'm sorry but that's nonsense, BW is as much as important as sample rate.

The two should match. If there's a serious mismatch then that's a red flag. You have to wonder who designed the device.

Exactly. A chain is only as good as its weakest link.

[nbritton]

Attached are some screenshots from my Analog Discovery measuring a 5V 1 MHz, 3 MHz, and 10 MHz square waves.

[mtdoc]

Attached are some screenshots from my Analog Discovery measuring a 5V 1 MHz, 3 MHz, and 10 MHz square waves.

Are you using the AD's AWG to produce the square wave?. If so, try a different signal source.

[Rupunzell]

20 Mhz @ 10mV square wave from a Tek 2102 pulse generator (circa late 1960's). Display using a Tek 7104, 7A29, 7B10 = 1Ghz real time.

Note the signal fidelity, low noise and wave form fidelity and image quality.

Gaussian response, no input filter worries, no worries about sampling rate issues, No fiddling with touch screens and menus, concerns about issues directly related to analog to digital conversion are gone as there is no analog to digital conversion. Just direct, accurate real time response and display of the input signal.

While DSO-MSO have their place in the test and measurement world, there is also a place for high quality CRT based time domain instruments.





Bernice

[Fungus]

Note the signal fidelity, low noise and wave form fidelity and image quality.

It's an illusion...

[Fungus]

Attached are some screenshots from my Analog Discovery measuring a 5V 1 MHz, 3 MHz, and 10 MHz square waves.

I don't own an AD but I would have expected slightly better than that...

The thing that makes it look really ugly is that it's not using sin(x)/x interpolation in the display. Is there any way to turn that on in the software?

[nbritton]

Attached are some screenshots from my Analog Discovery measuring a 5V 1 MHz, 3 MHz, and 10 MHz square waves.

I don't own an AD but I would have expected slightly better than that...

The thing that makes it look really ugly is that it's not using sin(x)/x interpolation in the display. Is there any way to turn that on in the software?

Well three things to realize, first the AD is an educational tool, second running both the AD's AWG and DSO eats up double? the sample rate, and thirdly I ran the test wrong, the default square wave on my AD's AWG is from +5V to -5V... I should have changed the DC offset.

[gojimmypi]

For your aliasing theory, it is absolutely right, so when trying to probe very fast signals, do not use a low sample rate scope. But it has nothing to do with BW, it's only a matter of sampling rate.

I'm sorry but that's nonsense, BW is as much as important as sample rate.

Here's are some screenshots for a quick test done with a 15MHz pulse (50% DC, generated by an Agilent 33522B) probed by a 3GHz 20GSa/s scope (LeCroy WavePro 7300A):

Thanks for spending the time to post that information & screen snips!

[alsetalokin4017]

Can I play too?

Scope: Rigol DS1054Z "unlocked" to 100MHz bw
Signal source: DataPulse (Systron Donner) DP-101
Connection: 2 lousy 50-ohm BNC patchcords spliced together with double-female, with Rigol 50-ohm thru-terminator at scope end

[gojimmypi]

Ok, I've spent hours on this (Dave has some really awesome video reviews!)... and I plan to order from amazon today (really can't beat the prime shipping, return poliucy, and 3% cash back on amazon/chase card)

So for others still researching and reading, I'm including some additional information:

First the Rigol page:

http://www.rigolcanada.com/products/digital-oscilloscopes/ds1000Z/ds1054z/

And Dave's feature list video:


Dave really expresses his opinion of the DS1054z at Time Index 31:30
https://youtu.be/W2qdtQkBKhc?t=1898

I had considered the other scopes below, however each had drawbacks: all are only 2 channel with limited storage depth. Hard to beat the Rigol 4 channels at 24meg max (6 meg when using all 4 channels)

Siglent SDS1102CML Digital Storage Oscilloscope, 100MHz, 7" TFT-LCD Display
http://www.amazon.com/gp/product/B00GQNNL1U

B&K Precision 2190D Digital Storage Oscilloscope, 1 GSa/s, 100 MHz Bandwidth
http://www.amazon.com/gp/product/B00SS0A0JU

Owon SDS7102 Deep Memory Digital Storage Oscilloscope 2-channel with VGA and LAN interface
http://www.amazon.com/gp/product/B006G54K3G

Tektronix TBS1052B-EDU 50 MHz, 2 Digital Channel Oscilloscope, 1 GS/s Sampling
http://www.amazon.com/gp/product/B00KAKI58Y

(I admit it was hard not to go with the usual gold-standard in oscilloscopes: Tektronix)

The 2232 mentioned in a prior post, although old, does have impressive specs: Sample Rate - 100 MS/s per channel. Effective sample rates up to 2 GS/s in repetitive storage mode (0.5 µs/div and faster in single-channel mode, 0.2 µs/div and faster dual-channel).

(it must have been expensive in its day). But not a lot of storage: Record Length - 4K or 1K selectable. 2K or 512 per channel in dual channel mode.

http://www.tek.com/datasheet/2232-digital-and-analog-oscillscope

There's also apparently some interesting software available (Thanks Dave, for including this in the video!), that can talk to the DS1054z via Ethernet LXI
https://www.eevblog.com/forum/testgear/free-ds1052eds1102e-software-for-linux/msg690621/#msg690621

In particular the stuff posted by marmad looks potentially very useful, if it works with the new DS1054z:
https://www.eevblog.com/forum/projects/software-tips-and-tricks-for-rigol-ds200040006000-ultravision-dsos/

I use this software to control the scope, view live waveforms and download screenshots or memory waveform data.
No need to install 1GB of bloatware (visa, rigol). Works fine for me.

http://www.teuniz.net/DSRemote/

Latest version supports LAN & USB.

Here's a link to the DSRemote open source linux software:

https://github.com/Teuniz/DSRemote

(I'm ever more excited to order my DS1054z now!)

From Dave's video, it seems the Rigol software is really dreadful. Not a showstopper, but could have made this an even more awesome product.

If I were to add a killer feature: an HDMI screen output would make the Rigol a ridilously cool scope.

Thanks everyone for the really great input! 

[Fungus]

Well three things to realize, first the AD is an educational tool

Yes, I'm not expecting greatness...

I ran the test wrong

Yep. That's more like I'd expect to see for that bandwidth and no sin(x)/(x) display.

[alsetalokin4017]

@Bernice...

Gotta love the 7104!   

"A one GHz _analog_ scope was good enough for my daddy..... "   

[Fungus]

From Dave's video, it seems the Rigol software is really dreadful. Not a showstopper, but could have made this an even more awesome product.

Rigol's remote control software? Yes, it's pretty bad. I guess you can't have everything for $400. 

I don't have any real reason to use it though. If I need a screenshot I just put a USB stick in the front connector and press the 'print' button.

If I were to add a killer feature: an HDMI screen output would make the Rigol a ridilously cool scope.

Also: 8 inputs, 1GHz bandwidth and a signal generator(!) 

[alsetalokin4017]

@gojimmypi:

Please allow me to recommend TEquipment as your USA vendor for the DS1054z. You really _can_ beat Amazon, I think. (Someone will send you the EEVblog TEquipment discount code if you ask for it....)

ETA: Two things: I had to return my original DS1054z under the TEquipment warranty (bad glitch on one channel) and had a replacement in hand in less than a week. And I just took delivery of an Extech LT300 light meter that someone else ordered for me from Amazon... and it arrived with a previously-opened and resealed box, a completely dead battery, and a clumsily reattached screenprotector film..... but it was sold as new.

[tautech]

Ok, I've spent hours on this ... and I plan to order from amazon today (really can't beat the prime shipping, return poliucy, and 3% cash back on amazon/chase card)


Siglent SDS1102CML Digital Storage Oscilloscope, 100MHz, 7" TFT-LCD Display
http://www.amazon.com/gp/product/B00GQNNL1U

B&K Precision 2190D Digital Storage Oscilloscope, 1 GSa/s, 100 MHz Bandwidth
http://www.amazon.com/gp/product/B00SS0A0JU

FYI
The B&K is a re-branded Siglent.

[Mosaic]

Regarding the issue of SPI requiring additional inputs to decode on a DS2000 series scope.
Technically true but practically not essential it seems as often one of the channels is occupied by dummy bytes:
http://www.bitwizard.nl/wiki/index.php/SPI_versus_I2C_protocols

[mtdoc]

Attached are some screenshots from my Analog Discovery measuring a 5V 1 MHz, 3 MHz, and 10 MHz square waves.

I don't own an AD but I would have expected slightly better than that...

The thing that makes it look really ugly is that it's not using sin(x)/x interpolation in the display. Is there any way to turn that on in the software?

Well three things to realize, first the AD is an educational tool, second running both the AD's AWG and DSO eats up double? the sample rate, and thirdly I ran the test wrong, the default square wave on my AD's AWG is from +5V to -5V... I should have changed the DC offset.

Well, you peaked my curiosity - so here is my AD generating and simultaneously recording a 10 MHz square wave (I had forgotten the AWG could do that high of frequency!) and for reference, the same signal fed into my 200 MHz bandwidth Rigol.

I'd say the AD does pretty darn well all things considered.

[Fungus]

I'd say the AD does pretty darn well all things considered.

Yep.

[gojimmypi]

another somewhat related question: is there any reason to have the 50 ohm adapter for a scope being used on relatively low frequencies (<100MHz) ?  what specific circumstances require a 50 ohm adapter?

[tggzzz]

another somewhat related question: is there any reason to have the 50 ohm adapter for a scope being used on relatively low frequencies (<100MHz) ?  what specific circumstances require a 50 ohm adapter?

99MHz is not "relaively low frequency". A 15pF scope probe with a 6 inch ground lead will resonate and ring at ~100MHz.

If you have a "low impedance Z0 probe" (which has a higher impedance than a so-called "high impeadance probe", the you will need a  50ohm termination.

FFI, see https://entertaininghacks.wordpress.com/library-2/scope-probe-reference-material/