w4dnr
New Member
Posts: 27
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Post by w4dnr on Oct 20, 2016 15:59:20 GMT -5
I understand the basic concepts of "pinging" the line, but with the AIM 4170, does that mean "ONE" ping at one frequency ... ie : a single-shot square wave where the detector window
looks at the whole line or is it multiple square waves with multiple receive windows ? I see the graph being generated from left to right / shortest to longest . Is this a software left-to-right movement based on just one pulse, or is the graph being populated by multiple pulses ?
Don W4DNR
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Post by Bob on Oct 21, 2016 9:01:33 GMT -5
The AIM actually scans with a steady state sine wave over the whole frequency range. The reflection coefficient is determined at each frequency and the Fourier transform is used to calculate the time domain response.
Traditional TDR's use a step pulse generator and they read the time domain response directly, but this requires a scope with a very high frequency response.
-- 73/Bob
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w4dnr
New Member
Posts: 27
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Post by w4dnr on Oct 22, 2016 21:57:23 GMT -5
Before doing a TDR, should I select STANDARD CALIBATION ( the whole frequency range )
if I have been using CUSTOM CALIBRATION previously for a specific frequency ?
Don W4DNR
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Post by Bob on Oct 23, 2016 11:32:43 GMT -5
The TDR function requires using Standard Cal because the whole frequency range of the AIM is used.
You don't have to worry about setting the Start/Stop frequency Limits, that will be taken care of automatically.
--73/Bob
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Post by Harold on Oct 24, 2016 18:17:46 GMT -5
One thing I discovered is that when TDRing into a system that has a waveguide to coaxial interface
the TDR scan only shows the length of your line to that transition. It seems to not receive the band
limited reflected signals for analysis. This with the new UHF analyzer.
Harold K5GVR
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