Setting The Gate Delay And Gate Length Properly, When Not Using The Gate Utility; Gate Not Occurring During The Pulse; Gate Is Occurring At The Beginning Of The Pulse - HP 8590 E-Series User Manual

Setting the Gate Delay and Gate Length Properly, When NOT Using the
Gate Utility
If the gate delay and gate length are not set properly, you may not be viewing an accurate
representation of a signal. For example, If the gate does not occur during the RF pulsed signal,
the amplitude of the signal displayed on the spectrum analyzer is lower than the actual signal
(see Figure 4-28).
Figure 4-28. Gate Not Occurring During the Pulse
The time gate is implemented after the resolution bandwidth filtering and before the video
filtering. The displayed signal is a result of the decay time for the resolution bandwidth filters
and is not an accurate representation of the input signal.
If the gate occurs at the beginning of the RF pulse signal or at the end of the RF pulse signal,
the signal displayed on the spectrum analyzer can be attenuated or contain transient signals
caused by the spectrum analyzer (see Figure 4-29). If this happens, decrease the gate length
and change the gate delay to place the gate output during the signal.
REF .0 dBm
10
SC FC
Figure 4-29. Gate is Occurring at the Beginning of the Pulse
In Figure 4-29, the peak amplitude has not been reached, and the transient response of the
resolution bandwidth filters adds noise.
Table 4-4 and lhble 4-5 provide the recommended initial spectrum analyzer settings when
measuring a signal without signal delay.
CLEAR
WRITE
HOLD A
. . . . . . . . . . . . . . . . . . . .
:
BLANK
RSWP
PRINTER
PRINTER
:
PRINTER
ADDRESS
:
PRT
O N
I
PRINTER
SETUP
SPAN 20.00 MHz
150 RT
A
RT
B&W
NENU
MENU
Making Measurements 4.33