Popular Post alfe Posted March 12, 2020 Popular Post Share Posted March 12, 2020 17 minutes ago, jabbr said: Does anyone measure jitter on an AP, I mean really ... you are using a 1Ghz+ scope to measure jitter on a 25-100 Mhz DAC clock right? Right, I mean in all fairness, the AP is designed to measure analog signals, not high speed digital... and so ... I can pretty much guarantee that you aren't seeing a 6 dB improvement compared to my 10Gbe switch, and certainly not compared to my 100Gbe switch in which the jitter budget is zero ... also both of these systems have been tested NOT TO PROPAGATE JITTER ... its just not allowed in modern Ethernet. I mean fair enough that some $12 switch is built like crap. Here are some jitter budgets: https://www.sitime.com/company/news/blog/what-you-need-know-about-phase-noise-and-jitter-high-speed-systems note that 100Gbe (4x25) is ) 0.061 picoseconds In all fairness to the EtherREGEN, my professional switches retail for >$30k (I paid a very small fraction). But they have dual SMPS PSUs and similarly my 100Gbe NICs are also powered off a bod standard server PSU via the PCIe bus... You can't even measure the low jitter (< 61 femtoseconds) on these puppies Ok, so let's forget this TP-Link or Trendnet whatever generic ancient spec Ethernet stuff, and at the very least compare against a very old Cisco device (I mean assuming you are looking at 100m Ethernet which spec is circa 1995 and is officially on "Legacy" status with the IEEE) For audio, only Planck time is valid. jabbr and pkane2001 1 1 Link to comment
alfe Posted March 13, 2020 Share Posted March 13, 2020 https://m.eet.com/media/1097137/measurejitter.pdf 😉 Link to comment
alfe Posted March 19, 2020 Share Posted March 19, 2020 On 3/13/2020 at 1:10 PM, jabbr said: @JohnSwenson: I read your white paper. You have identified the well known nonlinearity as described by Rubiola whereby power supply noise at eg 10Hz causes a frequency offset error in a crystal at f +|- 10Hz. Ok that’s all correct, however: There is not a well identified inverse nonlinearity whereby phase error an an input f +|- 10 Hz is downconverted to ground plane noise at 10Hz. If there is switching noise from a gigahertz input Ethernet signal, it will cluster at a gigahertz. On the other hand common mode noise transmission down a cable could cause 10Hz (or 60Hz) noise in a receiver. There is no known mechanism to say that 10Hz noise transmission by a gigahertz Ethernet cable has anything to do with Ethernet clock jitter as opposed to common mode noise.. The contradiction in this paper is to identify a non linearity from one side and assuming a Lorentzian shape of the spectrum from the other side. jabbr 1 Link to comment
alfe Posted March 23, 2020 Share Posted March 23, 2020 25 minutes ago, RussL said: Just trying to inject a little humor. Russ Objectivist! Link to comment
Popular Post alfe Posted March 23, 2020 Popular Post Share Posted March 23, 2020 19 minutes ago, Superdad said: That's nothing compared to the "moderator" at Audio Science Review this morning posting this vile gem: "I hear uptone claim to have a vaccine for coronavirus..." People are dying and this is the sort of crap we see?! They are jealous because you have a vaccine for jitter. jabbr, The Computer Audiophile, Teresa and 2 others 4 1 Link to comment
alfe Posted March 23, 2020 Share Posted March 23, 2020 My apologies Alex for my poor joke. Link to comment
Popular Post alfe Posted April 1, 2020 Popular Post Share Posted April 1, 2020 13 minutes ago, pkane2001 said: This being an ostensibly 'objective' thread, I'll take any objective evidence. If you can demonstrate in a properly controlled test that you prefer ER over a simple switch, I'll take that, too. pkane2001, Seraph and jabbr 3 Link to comment
alfe Posted April 3, 2020 Share Posted April 3, 2020 14 hours ago, jabbr said: This paper describes ways to measure Ethernet receivers in the presence of injected jitter, so called stressed eye pattern testing, again to ensure that input jitter is not retransmitted: https://www.tek.com/document/application-note/physical-layer-tests-100-gb-s-communications-systems 65W_28494_1_LR_Letter (2).pdf 2.01 MB · 4 downloads Now you are trying the Frankenstein design (let's create first and see what happen later)😁 Link to comment
Popular Post alfe Posted April 3, 2020 Popular Post Share Posted April 3, 2020 36 minutes ago, pkane2001 said: Ha! All three of the remaining four objectivists here are reporting subjective posts in Objectify? The horror! I've yet to report a single post by anyone since I joined CA, so I know it's not me 🤨 Not me , not Jon, the only objectivist I can think about is SandyK😂 DuckToller, sandyk, jabbr and 1 other 4 Link to comment
Popular Post alfe Posted April 3, 2020 Popular Post Share Posted April 3, 2020 30 minutes ago, Seraph said: I call fraud, snake oil and bullshit on this product. You can show some respect even if you are not convinced by the product. No one is putting a gun on your head to buy it. jabbr, sandyk, Teresa and 1 other 1 2 1 Link to comment
alfe Posted April 3, 2020 Share Posted April 3, 2020 12 minutes ago, jabbr said: It’s very possible that a cheap Ethernet switch might transmit common mode noise to the receiver. You mean phase noise, close in phase noise, deterministic jitter, periodic jitter...😄 jabbr 1 Link to comment
alfe Posted April 3, 2020 Share Posted April 3, 2020 5 minutes ago, Seraph said: I show respect when respect when respect is due. If you believe in science you can't have one without the other. Audiophile Neuroscience 1 Link to comment
alfe Posted April 3, 2020 Share Posted April 3, 2020 9 minutes ago, jabbr said: It’s been demonstrated that copper Ethernet can transmit common mode noise aka leakage current to receivers and in hospitals, particularly in ICIs where there might be direct cardiac electrodes, so-called Ethernet isolation filters are used (they weren’t developed for the audiophile market 😂) https://www.tripplite.com/rj45-network-isolator-ethernet~N234MI1005 Link to comment
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