NF FRA51602, Instruction Manual

Page: 159 / 286

5.2 Delay
5
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3
FRA 51602
5.2 Delay
If there is a response delay element in the equipment under test and the measurement frequency is changed,
the transient response causes an error in the measurement data. When using this instrument to measure
frequency response, that error can be reduced by inserting a delay after the frequency change and before the
measurement is started. The delay duration is set according to the time constant of the equipment under
test.
Particularly for equipment under test that has higher-order elements (steep filters, quartz oscillators, and
other elements that have high Q values), accurate measurement cannot be performed without a large delay.
Figure 5-1 Example of a response waveform that requires a delay
The measurement frequency is changed during normal frequency sweep measurements, when the sweep
begins (the frequency is returned to the starting frequency from the frequency at the end of the sweep), and
in spot measurement when the measurement frequency is changed, etc. There are two delay settings:
measurement delay (MEAS DELAY) and measurement start delay (START DELAY). The two types of
delay differ in the timing with which the delay takes effect. Both delays are set using
【
Measure
】
.
[MEAS DELAY] : The delay that is inserted each time the frequency changes during a sweep
[START DELAY] : The delay that is inserted only at the beginning of a sweep measurement or
at the beginning of a spot measurement.
OSC frequency = f1 f2
OSC output waveform
EUT response waveform
Time
Measurement waveform range
for delay = 0
Measurement window with
appropriate delay