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Usefulness of different TDR designs?

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rhb:
Without readable  scales it's a bit hard to compare things.  Does the Agilent actually use a continuous sweep? 

I was actually asking about what Joel Dunsmore calls "reflection masking" rather than intrinsic cable attenuation.   In geophysics we call  the portion of the incident wave reflected at an interface transmission loss.  Physics uses the same terminology for EM.

ocw:
The Agilent automatically places markers on the four distances with the least return loss and shows those distances and RL figures.  That obviously makes it easy to see any change in future measurements.  For the two TDR's I moved their one marker to the end of the coax.


--- Quote ---Does the Agilent actually use a continuous sweep?
--- End quote ---

My spectrum analyzer shows that the frequency range chosen (either automatically or manually chosen) is swept continuously in frequency.

vk6zgo:

--- Quote from: ocw on April 25, 2019, 04:46:37 pm ---There are a number of factors influencing the use of a TDR or Frequency Domain Reflectometry (FDR) measurements.  While I have used a Tektronix 1503B and various Riser Bond TDR's to locate and then correct many cable problems, FDR's are generally replacing TDR's since they do a better job of locating most faults.  See:  https://www.anritsu.com/en-US/test-measurement/solutions/en-us/distance-to-fault

Examples of this are shown in my attachments.  I am comparing a Tektronix 1503B to a Agilent E7495A.  The best example is probably comparing an inexpensive Chinese 2M BNC to BNC RG58 cable.  The end of the cable is connected to a 6 GHz 50 ohm load.  The Tektronix TDR display indicates that it is perhaps not the best cable in the world, while the Agilent FDR display clearly demonstrates that besides the connectors being marginal, the cable is not the best quality either.


The RG214 cable comparison shows the differences when measuring a better quality cable.

Additional cables are shown on just the Agilent FDR since the differences are more easily seen on that instrument.

--- End quote ---

I was confused by the distances in feet, not matching what I thought meant  "2metre  long" cable, not realising "2M"in this context was a part number.
I lost interest, but now I need to revisit your interesting postings.

ocw:

--- Quote ---I was confused by the distances in feet, not matching what I thought meant  "2metre  long" cable...
--- End quote ---

It was a 2 meter long cable being measured.  It is just that the cheap cable did not meets its velocity factor specification.

tomato:

--- Quote from: rhb on April 26, 2019, 05:49:42 pm ---If EEs want to have their own special meaning for ETS, they may do so.  But I am not interested in such abuses of language and mathematics.  Wiener, Shannon and Nyquist got it right and stated it properly.
--- End quote ---

You want to discuss instruments designed by EEs on an EE forum, but you reject the conventions used by EEs with a condescending attitude?  Good luck with that approach. 

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