a cable with a tee junction at 3m with an open stub. The two impulses are for a 19cm open-circuit stub and a 29sm open-circuit stub.
You've lost me already ...I know it must be really simple, but what is meant by "open-circuit stub"?
I've just been measuring unterminated lengths of coax.
"Open circuit Stub" is RF "slang" for sections of open circuit transmission line connected across the main line.---they are commonly used for filtering of unwanted signals.
For instance,a section of open ended line connected in such a manner will look like a short circuit across the main line at the frequency at which it is a 1/4 wavelength.(normally,the unwanted frequency)
To the wanted frequency,it will look like an open circuit,& will effectively be invisible to it.(you can have "short circuit stubs",too,& combinations of both)
The TDR,being wideband,sees it as an impedance mismatch,& will indicate how far down the cable it is.