University professor here: showing and decoding wire signals has become a staple in my teaching - very effective, eye-opening even for students that find the OSI layers too abstract to grasp on paper. Btw, I’m using this nice demo board (I’m not affiliated with the brand): https://www.batronix.com/shop/demoboards/Batronix-MSO-Demo-B...
…typically we decode I2C.
Oh, I‘ve equipped the lab with all kinds of oscilloscopes. I find a lower mid-tier product (like Rigol DHO 900/1000 series) most suitable: good enough resolution and nice quality-of-life features (many physical buttons / dials and input channels go a long way!), yet not too feature-packed and physically compact to still be approachable.
Yes, it’s absolutely useful. You need the logic probe (which I do have, but never use in „standard“ teaching) only if you plan (or need) to monitor more input signals than the analog ones on the scope.
In fact, to demonstrate the very physical foundation of digital computing, it is very useful to use the analog inputs and zoom all the way in to see the slight imperfections in signal transmission.
> Random equivalent-time sampling takes advantage of the nature of a repetitive signal by using samples from several trigger events to digitally reconstruct the waveform. Since sampling occurs on both sides of the trigger point, pretrigger capability is very flexible. Because repetitive signals are being sampled, the bandwidth of an equivalent-time scope can far exceed its sample rate.
Even if it's the same data, the bit stream will be a variety of 0 and 1s. The period of that waveform will then be 1 frame length / data transfer rate (or rather 1/4 frame length / data transfer rate as this is a QSGMII link). I wonder how the scope triggers on that. Trigger criterium would be a bit pattern, say the Ethernet frame preamble of 7 octects (* 10/8) spread across four streams ...
Otoh, at 5Gbps, a sample rate of "just" 10GS/s would be sufficient (barely).
I rather suspect the oscilloscope is capable of 1TS/s equivalent time sampling, but that mode wasn't used.
Here's a more specific example: PicoScope 9400 series supports just 500Msps per channel, however it's advertising "70ps transition time and 1TS/s (1ps resolution) random equivalent-time sampling", this sort of "equivalent sampling" is presumably where that seemingly crazy spec comes from.
Looks like max 50GS/s per their site. That also looks reasonable with the screenshot they have in the article showing 1ns / div horiz. But clarity on the data would be lovely. =)
Actually I take it back:
For the series 6B spec page...
Real-time: 50 GS/s (2 channels), 25 GS/s (4 channels), 12.5 GS/s (> 4 channels)
Interpolated: 2.5 TS/s
If you are an absolute nutcase, you could characterize a set of line stretchers and a multiplexer on a high end VNA then offset the inputs of the 4 channels on that UXR with them, take a capture and finally rebuild a 1TSamp/s signal out of the 4 results.
You have to have the 240V model of the scope to run all four channels at full rate (110GHz) though.
This reminds me of back in the day (1985) on my final year project, I'd designed a (6502 or 8080 based) SBC, my PCB design, my assembler and on first boot ... nothing happened.
With only a voltmeter in hand, I measured the voltages on the address lines - thankfully my dumb programming error was a very tight loop so it was easy to deduce where the looping was happening !
Could anyone recommend a budget tooling (has most features desired, please explain) to capture on wire like an oscilloscope. Help understand what kind of sample rates needed etc. features desired, cost and any recommended brand/models to get by. Thx!
I love the photo of the probe, and I bet it's very expensive. I wonder if the "A071626" sticker changes the impedance of the traces enough for you to notice :)
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…typically we decode I2C.
Oh, I‘ve equipped the lab with all kinds of oscilloscopes. I find a lower mid-tier product (like Rigol DHO 900/1000 series) most suitable: good enough resolution and nice quality-of-life features (many physical buttons / dials and input channels go a long way!), yet not too feature-packed and physically compact to still be approachable.
Do you happen to know if that batronix board useful to have even if you have a Rigol DHO 924S without the logic probe (PLA2216)?
In fact, to demonstrate the very physical foundation of digital computing, it is very useful to use the analog inputs and zoom all the way in to see the slight imperfections in signal transmission.
> I configured the oscilloscope to collect 100M samples at 1 TSPS
Typo? I didn't think we had sample rates anywhere near that high!
> Random equivalent-time sampling takes advantage of the nature of a repetitive signal by using samples from several trigger events to digitally reconstruct the waveform. Since sampling occurs on both sides of the trigger point, pretrigger capability is very flexible. Because repetitive signals are being sampled, the bandwidth of an equivalent-time scope can far exceed its sample rate.
https://www.tek.com/en/documents/application-note/real-time-...
Otoh, at 5Gbps, a sample rate of "just" 10GS/s would be sufficient (barely).
I rather suspect the oscilloscope is capable of 1TS/s equivalent time sampling, but that mode wasn't used.
You have to have the 240V model of the scope to run all four channels at full rate (110GHz) though.
With only a voltmeter in hand, I measured the voltages on the address lines - thankfully my dumb programming error was a very tight loop so it was easy to deduce where the looping was happening !
Some things were easier back in the day.
https://www.mattkeeter.com/blog/2022-08-11-udp/probes_full.j...