Concepts and Features
R&S
®
ZNB/ZNBT
177
User Manual 1173.9163.02 ─ 38
trace is shifted in vertical direction and centered around zero. In phase format, the
"Auto Length" corrected trace shows the deviation from linear phase.
Length and delay measurement, related settings
"Auto Length" is suited for length and delay measurements on transmission lines.
1. Connect a (non-dispersive) cable to a single analyzer port no. n and measure the
reflection factor S
nn
.
2. In the CHANNEL – OFFSET EMBED > "Offset" softtool tab, select "Auto Length".
The delay is diplayed in the "Delay" field, the cable length (depending on the
"Velocity Factor") in the "Mech. Length" field.
It is also possible to determine cable lengths using a transmission measurement. Note
that "Auto Length" always provides the
single
cable length and the delay for a propa-
gation in
one
direction.
The analyzer provides alternative ways for delay measurements:
1. Measure the reflection factor and select TRACE – FORMAT > "Delay" .
This yields the delay for propagation in forward and reverse direction and should
be approx. twice the "Auto Length" result. For transmission measurements, both
results should be approx. equal.
2. Measure the reflection factor and select TRACE – FORMAT > "Phase" . Place a
marker to the trace and activate TRACE – TRACE CONFIG > "Trace Statistics" >
"Phase/El Length".
Measure the reflection factor and select FORMAT > "Phase" . Place a marker to
the trace and activate TRACE > "Trace Statistics" > "Phase/El Length".
This yields the delay in one direction and should be approx. equal to the "Auto
Length" result.
The measurement results using trace formats and trace statistics functions depend on
the selected delay aperture and evaluation range. "Auto Length" is particularly accu-
rate because it uses all sweep points. For non-dispersive cables, aperture and evalua-
tion range effects are expected to vanish.
Use TRACE – MARKER > "Set by Marker" > Zero Delay at Marker to set the delay at a
special trace point to zero.
Preconditions for Auto Length, effect on measured quantities and exceptions
"Auto Length" is enabled if the measured quantity contains the necessary phase infor-
mation as a function of frequency, and if the interpretation of the results is unambigu-
ous:
●
A frequency sweep must be active.
●
The measured quantity must be an S-parameter, ratio, wave quantity, a converted
impedance or a converted admittance.
Offset Parameters and Embedding
