Concepts and Features
R&S
®
ZNC
31
User Manual 1173.9557.02 ─ 13
of a user-defined subrange termed the "Search Range") in order to find one of the fol-
lowing:
●
Absolute or relative (local) maxima and minima (minimum/maximum search).
●
Trace points with a specific response value (target search).
●
Trace segments with a shape that is characteristic for bandpass or bandstop filters
(bandfilter search); see
When the search is activated, the active marker is moved to the (next) point that meets
the search criteria. If the trace contains no markers, a marker M1 is created and used for
the search. The search result is displayed in the marker info field. If no search result can
be found, the marker remains at its original position.
Some search functions can be activated repeatedly in order to find all possible search
results. Moreover the analyzer provides a "Tracking" mode where the search is repeated
after each sweep.
Bandfilter Search
In a bandfilter search, the R&S ZNC locates trace segments with a bandpass or bandstop
shape and determines characteristic filter parameters.
Bandpass and bandstop regions can be described with the same parameter set:
●
A bandpass region contains a local maximum around which the magnitude of the
trace falls off by more than a specified bandwidth factor.
●
A bandstop region contains a local minimum around which the magnitude of the trace
increases by more than a specified bandwidth factor.
The analyzer locates bandpass and bandstop regions and determines their position
("Center" frequency) and shape ("Bandwidth, lower and upper edge", quality factor. For
a meaningful definition of the bandwidth factor, the trace format must be "dB Mag".
The info field contains the following search results:
●
"Bandwidth" is the n-dB bandwidth of the bandpass/bandstop region, where n is a
selectable bandwidth factor. The bandwidth is equal to the difference between the
"Upper Edge" and the "Lower Edge".
●
"Center" is calculated as the geometric mean value of the "Lower Edge" (LBE) and
"Upper Edge" (UBE) positions:
)
f
*
(f
f
UBE
LBE
Center
●
"Lower Band Edge" is the closest frequency below the center frequency where the
trace is equal to the center value minus n dB.
●
"Upper Band Edge" is the closest frequency above the center frequency where the
trace is equal to the center value minus n dB.
Screen Elements