Author Topic: Can I use a Rigol DS1054Z scope to see 10 Mb Ethernet bits?  (Read 2757 times)

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Offline DougSpindler

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Can I use a Rigol DS1054Z scope to see 10 Mb Ethernet bits?
« on: January 30, 2018, 02:48:28 pm »
I'm a college instruction teaching sever virtualization, Windows Server and computer networking (hubs routers switches).  So I'm more of a hobbyist than an EE.    I just managed to buy a Rigol DS1054Z scope.  I'd like to know if I can see an Ethernet bits/wave form on the screen.  I suspect gig and FastEthernet/100 Mb would be out of range.  But what about 10 Mb?  I'm going to assume the Rigol DS1054Z doesn't have a packet decoder for Ethernet.

Silly questions time.
I believe the Rigol DS1054Z is rated for 200 v input.  I live in the US.  If the scope max V is 200 I should be able to plug the leads into a 120vac outlet/170 v P-P with no problem....  Correct?     Scope should display a nice sine wave right?

 

 
« Last Edit: January 30, 2018, 02:50:42 pm by DougSpindler »
 

Offline imidis

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Re: Can I use a Rigol DS1054Z scope to see 10 Mb Ethernet bits?
« Reply #1 on: January 30, 2018, 03:18:00 pm »
Just a couple things to be aware of. The negative terminal probe is grounded, computers are grounded as well as some switches (though not likely a small hub/switch) however computers are.

The probes also account for your rating IE passive probes at 1x 150v 10x 300v so it's important to always keep in mind what your set to.

The ground is important to mention because if a rail is referenced to ground a short is possible. Which could result in issue as a short circuit can result taking out test gear and devices.

http://www.anuragchugh.com/notes/ethernetwaveform?tmpl=%2Fsystem%2Fapp%2Ftemplates%2Fprint%2F&showPrintDialog=1

This may help. Just be very careful. They ran the DSO off batteries to isolate it.

And yeah, you get into the pretty spiffy gear trying to get 100 meg to 1 gb ethernet.
Gone for good
 

Online ataradov

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Re: Can I use a Rigol DS1054Z scope to see 10 Mb Ethernet bits?
« Reply #2 on: January 30, 2018, 03:18:58 pm »
DO NOT PLUG THE SCOPE PROBES INTO THE WALL. That will be the end of it (or at least the channel).

What is it with people wanting to probe mains?

You will see 10 Mb Ethernet frames without a problem, but what do you expect to see there?
« Last Edit: January 30, 2018, 03:23:24 pm by ataradov »
Alex
 

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Re: Can I use a Rigol DS1054Z scope to see 10 Mb Ethernet bits?
« Reply #3 on: January 30, 2018, 03:22:13 pm »
Ethernet are isolated. It should be okay to probe them whatever way you like, and the worse case being distort the signal. Ethernet PHY drivers are current limited, and a shorted cable won't blow up the chip.
That being said, probe tip and probe return have different stray space capacitance and hence it may asymmetrically distort the signal if you probe the differential pair with probe and ground.
The proper way is to use 2 probes, one for signal+ and one for signal-, tie the common ground together to true ground. Use math - function to restore differential waveform.
 

Offline DougSpindler

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Re: Can I use a Rigol DS1054Z scope to see 10 Mb Ethernet bits?
« Reply #4 on: January 30, 2018, 05:04:47 pm »
DO NOT PLUG THE SCOPE PROBES INTO THE WALL. That will be the end of it (or at least the channel).

What is it with people wanting to probe mains?

You will see 10 Mb Ethernet frames without a problem, but what do you expect to see there?

I thought that might happen if the probe cfn lead was connected.

Would not an isolation transformer prevent it?

Or maybe I can find an old filamnet transformer and drop and isolate the voltage to around 6 volts.


10 Mb Ethernet uses Macnchester encoding.  So shoudl be able to see the clock and encoded data.  Should be very easy to pick ou the preamble and then the start bit.

Want to read Machecter encoding,.....  It's not that diofficu.    This book tells how.
https://www.amazon.com/Network-Maintenance-Troubleshooting-Guide-Solutions/dp/0321647416/ref=sr_1_1?s=books&ie=UTF8&qid=1517292167&sr=1-1&refinements=p_27%3ANeal+Allen


 

Online ataradov

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Re: Can I use a Rigol DS1054Z scope to see 10 Mb Ethernet bits?
« Reply #5 on: January 30, 2018, 05:09:56 pm »
Would not an isolation transformer prevent it?
That would be measuring output of the transformer, not the mains technically. And your original question has nothing about transformers.

Or maybe I can find an old filamnet transformer and drop and isolate the voltage to around 6 volts.
But why? Why do you want to see a sine wave?

10 Mb Ethernet uses Macnchester encoding.  So shoudl be able to see the clock and encoded data.  Should be very easy to pick ou the preamble and then the start bit.
Want to read Machecter encoding,.....  It's not that diofficu.    This book tells how.
I know how Ethernet works, but what do you want to do with those traces?  If it is just out of general interest, then go for it, it is safe and you may put those advanced triggering modes to a practical use.
Alex
 

Offline DougSpindler

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Re: Can I use a Rigol DS1054Z scope to see 10 Mb Ethernet bits?
« Reply #6 on: January 30, 2018, 05:10:44 pm »
Could you explain this?
The probes also account for your rating IE passive probes at 1x 150v 10x 300v so it's important to always keep in mind what your set to.

I also watned to ask what the x1 and x10 setting on the probe do?  Is it a voltage multypler?  If 10 volts is measeurd at x1 it woudl be 10v.  But at x10 it would be 100 volts? 

So in reality if the scope is rated at 200 volts per channel, at x10 mas votage would be 10v?

And what's the purpose of the x10?   Do most people use the scompe in x1 or x10?
 

Online ataradov

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Re: Can I use a Rigol DS1054Z scope to see 10 Mb Ethernet bits?
« Reply #7 on: January 30, 2018, 05:15:05 pm »
Could you explain this?
The probes also account for your rating IE passive probes at 1x 150v 10x 300v so it's important to always keep in mind what your set to.
Probes have a voltage rating of their own. Even if the scope input can handle 200 V, the probes may not.

I also watned to ask what the x1 and x10 setting on the probe do?  Is it a voltage multypler?  If 10 volts is measeurd at x1 it woudl be 10v.  But at x10 it would be 100 volts? 
It is a voltage divider. The probe will internally divide the voltage by 10, so you need to set your scope accordingly to see correct voltage measurements.

And what's the purpose of the x10?   Do most people use the scompe in x1 or x10?
x10 provides higher bandwidth and higher input impedance (less load on the DUT). Most people use x10 for day to day use. I epoxy my probes in x10 position, so there is no chance of accidental switching.
Alex
 
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Offline DougSpindler

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Re: Can I use a Rigol DS1054Z scope to see 10 Mb Ethernet bits?
« Reply #8 on: January 30, 2018, 05:17:03 pm »
Would not an isolation transformer prevent it?
That would be measuring output of the transformer, not the mains technically. And your original question has nothing about transformers.

Or maybe I can find an old filamnet transformer and drop and isolate the voltage to around 6 volts.
But why? Why do you want to see a sine wave?

10 Mb Ethernet uses Macnchester encoding.  So shoudl be able to see the clock and encoded data.  Should be very easy to pick ou the preamble and then the start bit.
Want to read Machecter encoding,.....  It's not that diofficu.    This book tells how.
I know how Ethernet works, but what do you want to do with those traces?  If it is just out of general interest, then go for it, it is safe and you may put those advanced triggering modes to a practical use.

Didn't thik I needed a transformr.  Fully I have a weller soldering iron.  (Had it for years).  I was soldering I think the negitive lead on a 5v circuit whihc was powered off.  To my surprice the circuit became live when the soldering iron touced the negative lead.    (I think I'm remembering that correctly.)

I'm teaching a college computer networking class to high school students.    Yes goal is to show a sine wave, vs digital clock/square wave.
Then the decode is to show what a comptuer can do in a billionth of a second a himan would take an hour or more.

 

Online ataradov

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Re: Can I use a Rigol DS1054Z scope to see 10 Mb Ethernet bits?
« Reply #9 on: January 30, 2018, 05:24:34 pm »
Didn't thik I needed a transformr.  Fully I have a weller soldering iron.  (Had it for years).  I was soldering I think the negitive lead on a 5v circuit whihc was powered off.  To my surprice the circuit became live when the soldering iron touced the negative lead.    (I think I'm remembering that correctly.)
I don't understand any of this.

I'm teaching a college computer networking class to high school students.    Yes goal is to show a sine wave, vs digital clock/square wave.
Then the decode is to show what a comptuer can do in a billionth of a second a himan would take an hour or more.

It would be better to get a signal generator. Low frequency ones can be very cheap from China. Manually decoding Ethernet frames is a laborious task that teaches absolutely nothing.

PS: Do you have a spell checker? Computers can do that fast as well.
Alex
 

Offline DougSpindler

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Re: Can I use a Rigol DS1054Z scope to see 10 Mb Ethernet bits?
« Reply #10 on: January 30, 2018, 05:33:42 pm »
Didn't thik I needed a transformr.  Fully I have a weller soldering iron.  (Had it for years).  I was soldering I think the negitive lead on a 5v circuit whihc was powered off.  To my surprice the circuit became live when the soldering iron touced the negative lead.    (I think I'm remembering that correctly.)
I don't understand any of this.

I'm teaching a college computer networking class to high school students.    Yes goal is to show a sine wave, vs digital clock/square wave.
Then the decode is to show what a comptuer can do in a billionth of a second a himan would take an hour or more.

It would be better to get a signal generator. Low frequency ones can be very cheap from China. Manually decoding Ethernet frames is a laborious task that teaches absolutely nothing.

PS: Do you have a spell checker? Computers can do that fast as well.

College professor = Limited bedget.  AC mains are free.

Kids are curious.  Seeing what's on the Ethernet cable is a good excercise.  I atarted teaching this after my buddy at Fluke Networks told me he stances stuednst to do it.  It gaves them and understanding of what's going on.

I'm old...  My time left on Earth is short.  Fixing autocorrect and spell checking with takes time form the amount i have left to live.  (Let's hope it will be another 25-30 years.....  But you never know.)






 

Online ataradov

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Re: Can I use a Rigol DS1054Z scope to see 10 Mb Ethernet bits?
« Reply #11 on: January 30, 2018, 05:37:23 pm »
College professor = Limited bedget.

You can't afford $10 device? https://www.ebay.com/itm/XR2206-1Hz-1MHz-Function-Signal-Generator-Sine-Square-Triangle-Wave-Output-kits/331976478823?epid=1685915901&hash=item4d4b571067:g:NzAAAOSwol5YxU05

  AC mains are free.
But also highly dangerous, especially around kids.

Fixing autocorrect and spell checking with takes time form the amount i have left to live.
I'm young, I don't want to waste any more of my life trying to decode your messages. I'll let others take over.
Alex
 
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Offline CharlieEcho

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Re: Can I use a Rigol DS1054Z scope to see 10 Mb Ethernet bits?
« Reply #12 on: January 30, 2018, 10:39:14 pm »
The 10 in 10baseT actually refers to MHz not megs so yeah, you're good.

The probe calibrator on the scope will show you a square wave. You can build a simple sig-gen on a breadboard, if even a cheap plastic-fantastic one is out of the question.

See, e.g. http://www.ti.com/lit/wp/snoa839/snoa839.pdf. You could even assemble it under an overhead projector (just validate that layout at home first, heh, demos like to go wrong.).

But if you just want to teach them waveforms, I might do it in the audio spectrum. That way they can *hear* the difference between the waveforms and see them used to make various sounds. I first learned about wavelength and waveforms when I took my Technician test at twelve years old, but  it was when I got curious about how electronic music is made and played around with some software synthesizers that I really started to get it in an intuitive way (as opposed to test signals, modulation, sub-carriers, band divisions and antenna lengths) .

Your students will probably be familiar with the heavy low end "wub wub" bass pulse used in dubstep. That's basically a sine wave, and more interesting then the AC mains for most kids.

I'd suggest downloading  VCrack, a virtual modular synth (https://vcvrack.com/), and some of its plugins that will give you more waveforms.  It has a scope window that will show the synthesized waveform.



If that's a bit much, maybe Syntorial which has early lessons on the waveforms.



It's meant for teaching music, and has educational licensing but even a demo copy might contain the early lessons, I don't remember.


Or you can just use a basic audio workstation like Audacity: https://www.audacityteam.org/ . YT:



If you really want to show them the 60hz power wave coming out of the wall in some way, maybe lug in a crappy turntable, lol. I get plenty of 60 cycle hum on mine and I don't think I'm putting 120v into my speakers. :P
« Last Edit: February 01, 2018, 12:52:53 am by CharlieEcho »
 
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Offline DougSpindler

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Re: Can I use a Rigol DS1054Z scope to see 10 Mb Ethernet bits?
« Reply #13 on: January 30, 2018, 11:19:47 pm »
College professor = Limited bedget.

You can't afford $10 device? https://www.ebay.com/itm/XR2206-1Hz-1MHz-Function-Signal-Generator-Sine-Square-Triangle-Wave-Output-kits/331976478823?epid=1685915901&hash=item4d4b571067:g:NzAAAOSwol5YxU05

  AC mains are free.
But also highly dangerous, especially around kids.

Fixing autocorrect and spell checking with takes time form the amount i have left to live.
I'm young, I don't want to waste any more of my life trying to decode your messages. I'll let others take over.

Its education, we have to supply our own chalk and markers.  College purchased a $7,000 smart board overhead projector.  Took nearly 10 months to buy the $100 bulb.  In the mean time nearly 1,000 students were affected and could not learn.

I will prevent my wife from buying a Starbucks's coffee so I can buy one.  (Thank you.)

Mains are dangerous.  In high school we use to cook hot dogs by connecting directly to the mains.

I appreciate your replies.  So for you I will working on my gramar and spelling.


 

Offline DougSpindler

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Re: Can I use a Rigol DS1054Z scope to see 10 Mb Ethernet bits?
« Reply #14 on: January 30, 2018, 11:38:33 pm »
The 10 in 10baseT actually refers to MHz not megs so yeah, you're good.

Got it, the scope is rated at 100 Mhz so this is 1/10th.    Means the scope could handle FastEthernet which is 100 Mhz.

Quote
See, e.g. http://www.ti.com/lit/wp/snoa839/snoa839.pdf.  You could even assemble it under an overhead projector (just validate that layout at home first, heh, demos like to go wrong.).

But if you just want to teach them waveforms, I might do it in the audio spectrum. That way they can *hear* the difference between the waveforms and see them used to make various sounds.

Excellent idea.  You are right they should hear the diference. 

You made me reallize of another way of doing it is to use Audacity.  It's an open source mixer/mkultitrack recorder softare.  I use it to created custom ringtones for my phones.  I've akso used to spead backwards.  But heres the best one.  Converting the mage stripe on the back of a credt card to an audio file.  In doing so you can see how the bits are encoded.  I have not been sucessful, but one could modify the bits in Aidacity and re-wrute the magnetic strip on say something like a driver's license.  The convience stores in state where I live require the cleaks to scan the mag stripe for age verification when purchasing alcohol.  (Yes there are easer ways to make the mod, but you have to admit this is a good one.

 



 

Offline abraxa

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Re: Can I use a Rigol DS1054Z scope to see 10 Mb Ethernet bits?
« Reply #15 on: January 31, 2018, 12:44:47 am »
I'm a college instruction teaching sever virtualization, Windows Server and computer networking (hubs routers switches).  So I'm more of a hobbyist than an EE.    I just managed to buy a Rigol DS1054Z scope.  I'd like to know if I can see an Ethernet bits/wave form on the screen.  I suspect gig and FastEthernet/100 Mb would be out of range.  But what about 10 Mb?  I'm going to assume the Rigol DS1054Z doesn't have a packet decoder for Ethernet.

10 Mb Ethernet uses Macnchester encoding.  So shoudl be able to see the clock and encoded data.  Should be very easy to pick ou the preamble and then the start bit.

Want to read Machecter encoding,.....  It's not that diofficu.

Currently, sigrok doesn't have a manchester decoder (https://sigrok.org/wiki/Protocol_decoders) but it's easy to write one. Writing a MAC (https://en.wikipedia.org/wiki/Medium_access_control) decoder to sit on top of the manchester decoder and then an LLC (https://en.wikipedia.org/wiki/Logical_link_control) decoder to sit on top of the MAC decoder is a little more work, but still very doable.

Since your focus is on network security, you could show how MAC spoofing works and that a spoofed packet is indistinguistable to the receiver from a real one. Just to give you some ideas.
 

Offline CharlieEcho

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Re: Can I use a Rigol DS1054Z scope to see 10 Mb Ethernet bits?
« Reply #16 on: January 31, 2018, 01:13:31 am »
Scopes roll off before their nominal max B/W so 100baseT will be pushing it. I'd stick with 10baseT -- you'll get a nice clean picture of the wave.

Plus, if you want to show actual traffic you're going to want to use a hub, and if you're like me all the hubs I have lying around are 10 meg. By the time fast ethernet was standard everyone was using switches and hubs had become (overpriced) test equipment.

You don't inspect inspect Wireshark capture live anyway, unless you're Lt. Data,  so might as well go with what you know won't challenge the equipment.
« Last Edit: January 31, 2018, 01:15:23 am by CharlieEcho »
 

Online rstofer

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Re: Can I use a Rigol DS1054Z scope to see 10 Mb Ethernet bits?
« Reply #17 on: January 31, 2018, 01:21:38 am »


There will be a test later!

If you simply must look at 60 Hz, put your finger on the end of the probe.  It will be a trashy signal due to all the switching power supplies in the neighborhood (fluorescent ballasts among other things).

A filament transformer or an AC wall wart is an acceptable way to view mains.  Measuring mains is truly an advanced concept and has been known to result in destroyed equipment.

You must remember, that scope ground lead is tied to earth ground.  So is one side of that USB cable you are using to power the Arduino from your PC.  All these grounds running around is a recipe for disaster if they are not treated carefully.

You can use the math A-B function with two probes (and channels) to take a differential measurement.  Remove the probe ground leads, they are not used and you don't want them dangling around.

A-B is not as good as a real differential probe but we use what we have.  Differential probes are expensive.

Everybody immediately gravitates to the idea of an isolation transformer to remove the ground reference from mains.  They 'float' the scope and remove the safety feature whereby all exposed non-current-carrying metallic surfaces are grounded.  I don't work on SMPSs but, if I did, I would be buying the proper probe and leaving all the safety features in place.

Sometimes they remove the ground reference on the neutral conductor and bring the safety ground through the isolation transformer and still wind up with a ground on the scope BNC connectors.

If you have the opportunity, use a powered USB hub to power up your Arduino projects.  I try to resist the temptation to plug my projects into my laptop USB connectors.  One mistake and my laptop is down one port, or worse, I'm out a laptop!
 
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Offline alsetalokin4017

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Re: Can I use a Rigol DS1054Z scope to see 10 Mb Ethernet bits?
« Reply #18 on: January 31, 2018, 02:02:12 am »
Argh! This thread makes me cringe, and I fear for the OP's oscilloscope.    :-BROKE

Some thoughts coming out of my cringe:

DougSpindler:  Please please do watch Dave's video linked just above by rstofer. Watch it several times.

Why do people with little scope experience always seem to want to probe the mains, first thing? It seems this comes up with every new scope owner.
Differential probing is the only safe way to probe the mains, especially if the house mains outlet is accidentally miswired, as the post about the soldering iron powering a circuit may indicate. But you have to understand what you are doing before you try it, since you can easily damage the scope or even hurt yourself badly.

Please please do construct a simple 555- based signal generator. For under 5 dollars in parts you can build a basic generator that will produce sine, triangle, and square wave outputs simultaneously. You can learn a lot by building this circuit and then probing around in it with your new toy precision test instrument.

See  http://8085projects.info/555-waveform-signal-generator-circuit.html  for just one example.



The following is greatly simplified and I'm sure we will have more input on the topics I mention.

100 MHz bandwidth is not necessarily a limit on the "frequency" that the scope can display. It IS a limit on the ability to display fast transitions, so at higher and higher frequencies a true square wave input signal will tend to look more and more sinusoidal.

The 1x, 10x probe settings are not "multipliers", they are _divisors_. That is, when the probe is set to 10x, this means that, say, a true 10 volt signal will be read as 1 volt by the probe, and the corresponding scope channel must be set also to 10x to display this as the correct 10 volt level.  Almost _all_ normal circuit testing should be done with the 10x setting as this will apply the least loading to the DUT, and it also helps to protect the scope input from inadvertent overloads. 99.999 percent of the time you will want your probe 1x/10x switch and channel settings to match. The Rigol and most other scopes default to 10x channel setting for a reason. Keep your probes set to 10x unless you have a special case for using 1x.

The Rigol DS1054z has Cat 1 inputs rated 300 VRMS. Does this mean you can measure a 3000 volt signal with a 10x probe? Better not try it -- you need a 100x probe with a rating higher than 3000V. My own 100x probe is only rated to 2000 V. But probes and inputs must be de-rated as to max voltage as the signal frequency goes up. See the Data Sheet for your probes, and look up the definition and limits of "Category 1" test gear. 

With isolation transformer: Don't float the scope, float the DUT !!  Also be aware that using, say, BNC patch cords to connect a floated scope to another instrument like a function generator this automatically connects the scope chassis ground to that other instrument, which may be normally grounded itself. SO if you float the scope but don't also float the FG, your floating is useless. Also many FGs have the BNC output shield (outer connector) connected to chassis ground and hence to mains ground, so you must be careful not to make groundloops when connecting scope and FG to a DUT. And remember that all probe "ground" reference leads are connected together at the scope chassis and thence to the mains cord ground connection. So if your DUT is floated with an isolation transformer, and the scope isn't, then connecting a probe reference lead to the DUT will make that connection to mains ground back through the probe, scope and line cord.


The easiest person to fool is yourself. -- Richard Feynman
 
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Online rstofer

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Re: Can I use a Rigol DS1054Z scope to see 10 Mb Ethernet bits?
« Reply #19 on: January 31, 2018, 03:24:22 am »
Bandwidth in the context of the DS1054Z...

A square wave is the sum of all odd harmonics from DC to daylight.  Note:  There may not be a DC component...

Given this, we need to think about how many terms of the summation are required to get a decent representation of 'square'.  The 5th harmonic might be good enough but by the time we get to the 9th, things should be looking a little better.  So, a 100 MHz scope can display a 20 MHz square wave with obvious distortion or a 10 MHz square wave that might look pretty good.  A 100 MHz square wave is going to look like a sine wave.

https://en.wikipedia.org/wiki/Square_wave

From the wiki:
Quote
For a reasonable approximation to the square-wave shape, at least the fundamental and third harmonic need to be present, with the fifth harmonic being desirable. These bandwidth requirements are important in digital electronics, where finite-bandwidth analog approximations to square-wave-like waveforms are used.
 
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Offline CharlieEcho

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Re: Can I use a Rigol DS1054Z scope to see 10 Mb Ethernet bits?
« Reply #20 on: January 31, 2018, 05:30:06 am »
Why do people with little scope experience always seem to want to probe the mains, first thing?

Because they're there, and folks know what a 60 Hz sine wave should look like (or that the DMM should read 120v and it's CATIII right?!?11), and it's within the BW of their new 100MHz scope.  And the front panel says it's good to 400vpk or whatever, right? It's a thing people feel like they understand.

Honestly, even I was curious despite knowing better from some radio background. But I wasn't sure why I knew better. Just like I somehow knew it would be a poor idea to hook up my HT to my scope and transmit directly into its front end to see my voice in the 2m or 70cm band -- even though I couldn't say exactly why. (Until I ran some searches and watched some videos.)
 

Offline imidis

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Re: Can I use a Rigol DS1054Z scope to see 10 Mb Ethernet bits?
« Reply #21 on: January 31, 2018, 06:06:54 am »
It's also easy to inadvertently ground a DUT as well, not thinking and hooking it up to USB on a computer, or a non isolated power supply.

You will have to teach the kids some basics of using it if they are going to do some probing.

Gone for good
 

Online rstofer

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Re: Can I use a Rigol DS1054Z scope to see 10 Mb Ethernet bits?
« Reply #22 on: January 31, 2018, 06:57:55 am »
120V RMS is 340V peak-to-peak and that is what the scope will try to display.

I really think 12V RMS is a better place to play since the P-P voltage is just 34V.  It's safer for students as well.

VP-P = VRMS * 2 * sqrt(2)
 
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Offline JohnBee

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Re: Can I use a Rigol DS1054Z scope to see 10 Mb Ethernet bits?
« Reply #23 on: January 31, 2018, 03:07:31 pm »
I don't see what all the fuss is about tbh. if you're going to probe the main, then just don't use the ground lead - couldn't be simpler really
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Offline alsetalokin4017

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Re: Can I use a Rigol DS1054Z scope to see 10 Mb Ethernet bits?
« Reply #24 on: January 31, 2018, 04:19:12 pm »
I don't see what all the fuss is about tbh. if you're going to probe the main, then just don't use the ground lead - couldn't be simpler really

... and keep your fingers crossed that your cheap Chinese probe doesn't have some internal problem like poor insulation ...    :-BROKE

Actually it _could_ be simpler: Just don't do it.    :horse:
The easiest person to fool is yourself. -- Richard Feynman
 


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