[TowerTalk] TowerTalk Digest, Vol 117, Issue 9

[Roger D Johnson]

Hi Jim...

I'm used to the old Tek pulse type TDRs. What would be the effect on the trace 
of a swept frequency TDR
with FFT when the line is terminated with an antenna with several resonant 
points, such as Roger's? The
one trace I saw on the Array Solutions site for the AIM 4170 looked fine but the 
load was a resistive.

73, the other Roger

On 9/4/2012 1:17 PM, Jim Brown wrote:
> On 9/4/2012 10:00 AM, Spencer wrote:
>> You need a FAST rise time pulse generator with variable repetition rate and 
>> pulse width. A good scope. A test setup.
>> ANY Z discontinuities will cause a reflection and will show up on the scope 
>> trace. 
>
> There are several ways to skin this particular cat.  That's one of them. 
> Transforming a frequency sweep is another, and has been widely used in the pro 
> audio world for at least 30 years. One of the major advantages is signal to 
> noise level.  Another is that you can limit the response to the frequency 
> range in which you are interested. For example, small discontinuities that 
> would be more problematic at UHF can be ignored by using a sweep that only 
> goes to 100 MHz, and those discontinuities emphasized by using a sweep that 
> begins at 100 MHz or or so and sweeps to a higher frequency.
>
> 73, Jim K9YC
>
>
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