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Time-Domain Reflectometry

David Escandon
Expert 2175 points

TI Team,

I'm in the process of developing a cable tester that basically check for shorts and opens. In some cases, I would not have clear access to the cable, but the tester will need to have a PC interface.

I was looking at using a high speed data converter to both transmit and receive the test signal. The data would then be transmitted to the PC for analysis. Has the TI team worked on this type of application, and if so, what are the general recommendations for the ADC and DAC.

Any information you can provide is greatly appreciate.

http://en.wikipedia.org/wiki/Time-domain_reflectometry

-David

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    TI__Genius 17390 points

    Hi David,

    I do not have much experience with this application. From that article, it sounds like the limitation is the rise time of the system. You would need to determine the necessary rise time and choose a DAC based on that. I'm not sure how to determine the necessary rise time.

    On the ADC side, I would think that you would first want to select an ADC that is fast enough to give you the time resolution needed. The time resolution will be determined by the sampling period (1/Fs). I suppose you could determine the needed time resolution by knowing the propogation delay per unit length and the distance you want to be able to resolve (1 m? 10 m?).

    Second, on the ADC side, you want a part with good enough SNR to sense the reflected waveform. I suppose this would be determined by the minimum impedance difference you want to detect as well as the loss of the cable. The longer the distance you want to be able to measure, the more loss, and the better the SNR would need to be.

    Note that I have no experience with this and these are just my thoughts on the subject...

    Regards,
    Matt Guibord