R&S ZNB Series User Manual page 352

®
R&S ZNB/ZNBT
The three grids can be calculated repeatedly in any order; the analyzer always starts
from the original set of sweep points.
For more information, refer to
Remote command:
CALCulate<Chn>:TRANsform:TIME:LPASs
Automatic Harmonic Grid
If enabled (default) the frequency grid is automatically kept harmonic.
Remote command:
[SENSe<Ch>:]HARMonic:AUTO
DC Value
The control elements in this section define the measurement result at zero frequency
and in the interpolation/extrapolation range between f = 0 and f = f
enabled after a harmonic grid has been established.
Defining the low frequency sweep points
After calculating a harmonic grid, the analyzer must determine the value of the mea-
sured quantity at grid points below the analyzer's minimum frequency f
The following figure shows a scenario where the harmonic grid was calculated with
fixed "Stop Frequency and Number of Points". The DC value and the values at the two
additional red points must be extrapolated or interpolated according to the values at
the measured sweep points (blue dots).
●
If the properties of the DUT at f = 0 are sufficiently well known, then it is recom-
mendable to enter the DC value manually ("Manual Entry").
Examples: At f = 0 the reflection factor of an open-ended cable is 1. It is –1 for a
short-circuited cable and 0 for a cable with matched termination. If a cable with
known termination is measured, enter these numbers as DC values.
●
The "Extrapolate" button initiates an extrapolation of the measured trace towards f
= 0 and overwrites the current DC value. This function can be used for a consis-
tency check.
●
"Continuous Extrapolation" initiates an extrapolation of the measured trace towards
lower frequencies, so that the missing values (green and red dots) are obtained
without any additional input. The extrapolation is repeated after each sweep.
After setting or extrapolating the DC value, the analyzer then calculates the remaining
values (red dots) by linear interpolation of the magnitude and phase.
Remote command:
CALCulate<Chn>:TRANsform:TIME:LPASs:DCSParam
CALCulate<Chn>:TRANsform:TIME:LPASs:DCSParam:CONTinuous
User Manual 1173.9163.02 ─ 62
Chapter 4.7.2.4, "Harmonic
GUI reference
Trace Config softtool
grid", on page 225.
. They are
min
.
min
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