38 Replies to “Clock synchronization and Manchester coding | Networking tutorial (3 of 13)”

  1. At 7:10 Just for information the electrons in in wire move at a very slow speed (few milimeters per second).
    What it is really important here is not how elecrons move but how the electromagnetic waves propagate in the wire.
    Anyway, this video is really interesting because you explain in a very simple way things that is really not obvious to understand for a lambda person.

  2. BEN, where can i find a controller that can reproduce the manchester code? I have an animatronics show that used the manchester fm2 code and want to be able to program new shows. Please advise.

  3. Why not use something like 5V for 0 and 10V for 1? Then you don't need a clock, because each data point would be either 5V or 10V. You would send them in pulses. So 0V->5V->0V would mean it's a 0 and 0V->10V->0V would mean it's a 1. There would be no 5V->10V and vice-versa transitions.

  4. This is kinda similar to the encoding used in USB wires. The difference is that in the USB standard, 0 is encoded as a transition (either way), and 1 is encoded as no transition.

  5. I have recently bought an old HP8073 Pattern generator to play with. Thanks for this video you have reminded me of my university communications classes nearly 20 years. All I need is for you to do a video on multi mode and stepped index fibres and I will truly be back in the day. Many thanks. PS I went to Manchester University

  6. So, basically, Manchester coding is about half the speed of what the processing hardware can handle. It may have uses where the "cable" speed is the limiting factor, but otherwise, that sounds like a dramatic lost in efficiency.

    If two clock are not strictly adjusted to the same frequency, but "close", could they not "agree" to send "n" bits, then resynch them, say with a start bit, so they will, in theory, always safely read the data without slip ? Is it not what serial communication was doing? And thus, your efficiency will be more like around n/(n+1) instead of 0.5, as for Manchester coding as I understand it ( assuming that the cable transmission speed can support a speed as good as the processing one involved by the hardware at the "terminals").

  7. I don't often comment on Youtube videos but I would like to just say that you have been an amazing teacher and provided a fantastic overlook on manchester coding so thank you for finally making me understand it haha.

  8. Interesting. I'd never heard about Manchester coding. Doesn't it necessarily involve sacrificing half whatever your medium's maximum possible throughput is though? I'm just thinking you could be signaling in a nonManchester twice in the same period since you don't have to have a transition to represent a symbol.

  9. Would it make more sense to us a ternary system in networking instead of binary to avoid the clock? For instance a signal that goes from 2 to 0 could be interpretted as 0 and 2 to 1 would be 1. 0 to 1 would be 0 and 0 to 1 would be 1. 1 to 0 would be 0 and 1 to 2 would be 1.

  10. We used clocks because we couldn't reliably interpret the data which was recieved. Using clocks both the communicating nodes know at what rate they should transmit/read the data off the wire.
    So u mentioned gps and using another wire for clock sync as a way to sync clocks between these nodes. I dont understand how Manchester coding gets rid of the clock problems u mentioned, as u still need to read the data at some regular interval i.e u still need a clock right? The reciever can still read at a faster rate or go out of phase even if Manchester Coding is used, so can someone explain me how does it solve the clock issues?

  11. The contrast between the lines and the background is really poor.
    It feels like you've recorded on lower resolution than your display and some lines are thus almost invisible. I, and I'm sure many others, would appreciate it if you can upload the video back with proper resolution or with thicker line width and sharper contrast so it's easier to watch.

    The content itself is great regardless!

  12. your comments around 4:30 are misleading. No-one uses GPS satellites or atomic clocks to synchronize bus clocks. It provides a lot of pointless information (you don't care about the date or time of day when trying to shift in bits from a serial link), and wouldn't even be accurate enough for modern communication links that signal in the realm of hundreds of MHz or in the GHz. Plus it just moves the problem; how do you communicate between that super-duper clock and the rest of the computer?

    I understand you're intentionally suggesting two "bad" options before presenting realistic ones, but i'm not saying they're bad options, i'm saying they're nonsensical.

  13. seriously i have read 100's of times about clocks and coding but never able to visualize and understood like this before !!! crisp and clear , even a first timer can easily understood , superb!!! thanks !!!

  14. if you use Manchester coding to send the message 0000 0000, won't it be misinterpreted as 0101 0101 0101 0101 ? since the clock appears to be regular?

  15. Apologies, I'm afriad I still don't understand. Where is the clock with Manchester encoding? Sorry, I know it's a failure of understanding on my end, but I don't see the difference between a wire sending a signal and another sending a clock, and the Manchester encoding. Is the clock somehow bound up with the signal being transmitted, in a way that it isn't with the other set-ups? Thoroughly enoying this series, thank you.

  16. I'm from Manchester and had not heard about Manchester Coding. My old mathematics teacher had worked in the computer department there.

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