Rohde & Schwarz R&S UPP, Руководство пользователя

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Instrument Functions
R&S
®
UPP
459 User Manual 1411.1055.32 ─ 10
onds, depending on the sampling rate. What may actually cause problems are delays
and settling times that occur in the "DUT" and, possibly, also on the transmission lines
from the generator to the "DUT" and from the "DUT" to the analyzer.
If they are known and constant for all signal changes that occur, the total delay may
be entered as "Start Condition Delay", and is then treated as a waiting time prior to the
start of the measurement – same as the internal delays.
If external delays and settling times are known but not constant , the worst-case
value can be entered as the delay. In the case of most measurements, however, this
will unduly extend total measurement time, especially where the actual measurement
time is significantly shorter than the waiting time. Conditions are particularly difficult if
external waiting times or the settling characteristics are
unknown or if an external sig-
nal source is used.
For all of these cases, it would be preferable to determine – by way of measurement –
the time at which the DUT settled, and only then to carry out the desired measurement.
The purpose of the settling method described here is to determine the settling time by
means of a measurement. The basic idea is to perform as many measurements as
possible while settling is still in progress and to determine the time at which the signal
has settled to an extent that the measured value can be regarded as stable. This time
is determined based on the – continuously decreasing – difference between succes-
sive measured values.
The settling method is particularly reliable when combined with a trigger condition, as
with an external sweep or an external level trigger. In such cases, the trigger condition
is not fulfilled until a signal change is detected in the measured value and stabilizes
over several measurements.
If there is no such trigger condition (such as with manually started single measure-
ments), in the case of very long delays or very short measurement times it may happen
that the desired number of measurements is completed before the signal change
becomes visible on the analyzer.
With manually started single measurements, therefore, the external signal delay should
be entered as exactly as possible as "Delay" under "Start Condition", while the settling
method is activated as well.
●
The external signal delay is entered as a fixed delay under "Start Condition".
●
The settling time is dynamically measured with the settling method.
The following types of settling can be activated and also combined with one another as
desired (i.e. several types of settling can be used simultaneously):
●
Settling in the "Start Condition" menu, i.e. with an external level or frequency
sweep or with an external level trigger. An additional delay is not required.
●
Function settling in the case of distortion measurements and (most) level measure-
ments. As the measurement time becomes shorter relative to the signal delay, it
becomes more important to compensate for the signal delay.
●
Frequency Settling (not for multichannel analyzers)
●
Phase Settling (not for multichannel analyzers)
Settling Methods