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Recent content by cmd

  1. C

    Help for iFFT in Matlab

    Do you have any idea about this return loss value difference?
  2. C

    Help for iFFT in Matlab

    Hi jks, i also dont have any idea about windowing. With my code i locate the fault at the same position with anritsu cable analyzer, but return loss values have some differences from the anritsu's results. You said that agilent explained that but it doesn't contain enoug information. I uploaded...
  3. C

    Help for iFFT in Matlab

    Hi jks, Thanks for your advice. I had already fixed (rloss/10) problem. But your advice about log10 works my code. The measured RL value at 24.88 m was 3.59 dB. With Matlab iffft i calculate at 28.8m with 5.263dB. There is still a problem with the values but it is better than former I uploaded...
  4. C

    Help for iFFT in Matlab

    Hi everyone, There is a problem somewhere in the code. The time domain localization is true but return loss values doesn't match. In order to match return loss values i have to multiply the ifft result with a factor which changes in every experiment data. It shouldn't be so. Where is the...
  5. C

    Return Loss Measurement Basics

    Hi FvM, Thanks for your reply. You said the phase information is necessary for distance to fault measurements. The Anritsu's DTF aplicatin note says"The FDR technique requires a swept frequency RF signal. The Frequency Domain Reflectometry principle involves vector addition of the sources output...
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    Return Loss Measurement Basics

    According to the distance to fault application notes from Anritsu, it has to be measured magnitude and also phase information between incident and reflectected signals from the cable in order to get transform frequency domain data to time domain data. That's why for distance to fault measurement...
  7. C

    Return Loss Measurement Basics

    Yes you are right FvM, We had talked about TDR and FDR and their advantages. TDR theory is basic and easy to understand and apply. But FDR offer a selected frequency range measurment which is important for pass band applications. Also measurement at high frequency provide to see small faults on...
  8. C

    Return Loss Measurement Basics

    E Kafeman, Thank you for your helpfully reply. My graduation project is mainly about time domain reflectometry and frequency domain reflectometry methods for fault locating on RF and Microwave coaxial cables. I made some experiments about TDR with RG6 and RG58 coaxial cables and about FDR with a...
  9. C

    Return Loss Measurement Basics

    Thank you for your replies, E Kafeman, I have a graduation project about fault location on coaxial cables. For the experimental study i needed create a fault on the coaxial cable. That's why i bent the cable and destroyed it. I should show that the device can locate RF faults on a feeder...
  10. C

    Return Loss Measurement Basics

    Hi E Kafeman, Thank you for your reply! I uploaded the bent cable used in distance to fault measurement. I measured at the deformed point a return loss -9.92dB at 700-1000MHZ and -8.48dB at 1700-2000MHz. Do you think its normal? In which frequency range from these should be expected that return...
  11. C

    Return Loss Measurement Basics

    Thanks for your reply FvM, You say that at higher frequencies returns more power from a bend fault,so it can compansate the attenuation at higher frequencies. That's why the return loss values at higher frequencies were measured more then lower freq. Did i understand right? But i think that...
  12. C

    Return Loss Measurement Basics

    Hi FvM, You are right, i should give some more details. I made this measurements with Anritsu Site Master S331D cable and antenna analyzer. I have a 25m long 1/2" feeder cable for my experimental purpose. At first i made some measurements at 700-1000MHz range. I calibrated the device with its...
  13. C

    Help for iFFT in Matlab

    Anritsu Site Master use chirp z transform for transforming data from frequency domain to time domain in order to zoom the trace. With ifft we create a time domain sequence with measurement points N between dt*[0:NFFT-1] and distance domain sequence until to max distance range 206meter. Then we...
  14. C

    Return Loss Measurement Basics

    Hi albbg, Thank you for your reply. Did you look the last DTF traces i uploaded. First peak at 19.01m is a bend fault and the second peak at 24.88m is the end of the feeder cable. I think the measured RL values at 1700-2000MHz should be less than values at 700-1000MHz because cable loss is...
  15. C

    Return Loss Measurement Basics

    Hi, I made a distance to fault measurement on a bent feeder cable at different frequency ranges. First test was made at 700MHz-1GHz and the second was at 1700MHz-2GHz. The return loss values at high frequency range measured less than first measurement. But i think because of cable loss return...

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