From Oscilloscope to Wireshark: A UDP Story (2022)

(mattkeeter.com)

61 points | by ofrzeta 3 hours ago

2 comments

  • Retr0id 2 hours ago
    > I configured the oscilloscope to collect 100M samples at 1 TSPS

    Typo? I didn't think we had sample rates anywhere near that high!

    • nativeit 1 hour ago
      > 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-...

      • Retr0id 1 hour ago
        But you can't use equivalent-time sampling for something non-repetitive like network packets.
        • Aurornis 59 minutes ago
          For measurements like this the SDK will usually include some utilities to send the same data over and over on a port.
      • nativeit 1 hour ago
        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.
    • KK7NIL 2 hours ago
      A Keysight UXR can do one quarter of that, 256GS/s, but a Tektronix 6 series is limited to 25 GS/s iirc, so you're right.
      • Junk_Collector 55 minutes ago
        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.

        • jacquesm 10 minutes ago
          Hehe, take that Nyquist ;)
      • HunterWare 1 hour ago
        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. =)
        • HunterWare 1 hour ago
          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