Measure Cable Length with an Oscilloscope

Today we take a crack at measuring some coax cable using TDR on an oscilloscope with the help of a pulse generator. Cable length can be calculated by sending a pulse down a cable and measuring how long it takes for the pulse to return.
If you don't have a pulse generator, here are a couple of cool little circuits from fellow RUclipsrs:
Mr. Carlson's Lab TDR: • "TDR" or Time Domain R...
W2AEW TDR circuit: • #88: Cheap and simple ...
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[@fullwaverecked]

Or TDS. Great video! Always dig the way you explain complicated concepts, you always crush it! Cheers!

[@jamesdriscoll9405]

Always remember, a portion of your transmission will be reflected back to you.

[@electronicengineer]

This man just explained an extremely complex measurement setup and executed it in such a clear and concise way, that anyone can understand and grasp it! I wish that I would have had the opportunity to have you as my professor in college. BRAVO sir!! Fred

[@AmRadPodcast]

Thanks!

[@electronicengineer]

@@AmRadPodcast You are most welcome as it is the truth. Fred

[@k5la144]

If you have a network analyzer then you can check the impedance of a dummy load. I find many bird dummy loads are not exactly 50 ohms.

[@BaconbuttywithCheese]

Very well presented and explained. More to dig into!

[@Bunno1177]

Have done similar on site with high voltage cables

[@acestudioscouk-Ace-G0ACE]

Thanks for making this video, very interesting and useful.

[@TonyBarr99]

Thank you! Great as always. How can something so technical sounding as Time Domain Reflectometry be so darn easy to understand? Of course, when explained by a great teacher! It is so fascinating to know that I have the equipment in my home lab to measure the speed of light!

[@ehsfrac]

Very interesting! Excellent explanations!

[@FEPLabsRadio]

Great video Derek. I need to go back and look at mine again. If I remember, I didn't have the same wave form. Also, I didn't have a pulse gen at the time, and that might have been the difference. Hopefully, I did math right, it is a pretty simple formula.

[@AmRadPodcast]

In your case the return signal is stacked (summed) on top of the initial signal, which is still ongoing. In my case, the pulse generator goes hi/low before the return pulse, so you see two individual blips.

[@electronic7979]

👍

[@asunasposibol]

Thanks for your video. Would it work with a rise time < 20 ns? That's the best my frequency generator can get (FeelTech FY3200S)