How to measure the length of network cable

Discussion in 'Embedded Systems and Microcontrollers' started by speed1, Mar 9, 2012.

  1. speed1

    Thread Starter New Member

    Mar 9, 2012
    Hi all,
    wishing you nice weekend :D
    I have a project to do a network cable tester, I need to add a function of measuring the length of the network cable how to do that.
    please if you have any idea please share it we may get benefit.
    thank you
  2. n1ist

    Active Member

    Mar 8, 2009
    Look up Time Domain Reflectometry or TDR. Basically, send a pulse down the cable and time how long it takes for the reflection from the far end to come back.
  3. vpoko


    Jan 5, 2012
    I don't want to hijack this thread, but I'm curious about TDR. How would you measure the echo with enough time precision to get an accurate reading? With the speed of light being about 300 million meters per second, would you need a device capable of sampling at 300 MHz to be able to get accuracy to within a meter, or are there other tricks that can be used to enable slower devices to take this measurement?

    Edit: Never mind, I looked it up and it appears it's not just measuring return time (reflection magnitude, shape, and duration are involved, at least according to the Wikipedia article).
  4. nsaspook

    AAC Fanatic!

    Aug 27, 2009
  5. speed1

    Thread Starter New Member

    Mar 9, 2012