R&S ZVB - Page 515

R&S
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ZVA / R&S
®
ZVB / R&S
®
ZVT GUI Reference
Channel Menu
Operating Manual 1145.1084.12 – 30 500
always provides the single cable length and the delay for a propagation in one direction.
The analyzer provides alternative ways for delay measurements:
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.
Measure the reflection factor and select Trace – Format – Phase. Place a marker to the trace and
activate Trace – Trace Funct – Trace Statistics – Phase Delay / 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 accurate because it uses all sweep points. For
non-dispersive cables, aperture and evaluation range effects are expected to vanish.
Use 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 information as a
function of frequency, and if the interpretation of the results is unambiguous:
 A frequency sweep must be active.
 The measured quantity must be an S-parameter, ratio, wave quantity, a converted
impedance or a converted admittance.
The effect of Auto Length on S-parameters, wave quantities and ratios is to eliminate a linear
phase response as described above. The magnitude of the measured quantity is not affected.
Converted admittances or impedances are calculated from the corresponding Auto Length
corrected S-parameters. Y-parameters, Z-parameters and stability factors are not derived from a
single S-parameter, therefore Auto Length is disabled.
Auto Length for logical ports
The Auto Length function can be used for balanced port configurations as well. If the active test
port is a logical port, then the same length offset is assigned to both physical ports that are
combined to form the logical port. If different length offsets have been assigned to the physical
ports before, they are both corrected by the same amount.
Remote control:
[SENSe<Ch>:]CORRection:EDELay<port_no>:AUTO ONCE
Auto Length and Loss
Determines all offset parameters such that the residual group delay of the active trace (defined as the
negative derivative of the phase response) is minimized and the measured loss is minimized as far as
possible across the entire sweep range. Auto Length and Loss involves a two-step procedure:
 An Auto Length correction modifies the phase of the measured quantity, minimizing the residual
group delay. The magnitude of the measured quantity is not affected.
 The Auto Loss correction modifies the magnitude of the measured quantity, leaving the (auto
length-corrected) phase unchanged.
If Auto Length and Loss is used with a line connected to a test port, the end of the line should be left
open.