Agilent Technologies ESA Series User's/Programmer's Reference page 72

Front-Panel Key Reference
Det/Demod
Demod Time
It is normal to hear clicking sounds when the Auto Alignment function
NOTE
is On. During retrace, a small portion of the analyzer circuitry is
realigned. Some of the switching of the analyzer circuitry is done using
relays. It is the rapid switching of these relays during retrace that
causes the clicking sounds. To eliminate the clicking sounds, turn the
auto alignment off by pressing
When this is done, the
periodically. Refer to the Specifications Guide for your instrument to
learn more information on how often to perform
auto alignment is off.
Squelch
72
Allows you to set the time, in non-zero spans, to pause
and demodulate the signal after each sweep. The
demodulated signal can be heard during demodulation
when in mode. In zero span, demodulation
Speaker (On)
is performed (and can be heard) throughout the sweep.
With non-zero spans, in AM the Video BW is set to 3
kHz and the Resolution BW is set to 10 kHz. In FM, the
Video BW is set to 30 kHz and the Resolution BW is set
to 100 kHz.
When AM or FM demod is enabled, the instrument will
tune to the marker frequency and wait for the Demod to
take place.
Demod Time
FM demod is selected, and span is >0 Hz. For long
demodulation times, pressing
is set to will abort the Demod function. The
Factory
default value is 500 ms.
Key Access:
Det/Demod
System
, function should be performed
Align Now All
Allows you to adjust the squelch level. The squelch level
mutes weak signals and passes strong signals. Only the
audio level is affected. If the internal speaker is On,
audio signals are not output unless the signal strength
exceeds the squelch threshold.
The squelch level does not affect the rear panel AUX
VIDEO OUT signal. Squelch level is indicated on screen
by the numbers 0 to 100, with 0 being the minimum
threshold (all signals are passed) and 100 being the
maximum threshold (no signals are passed). The
default squelch value is 0. Squelch is active only when
FM demod is selected and it is only available when the
Option AYQ hardware is used as the instrument's FM
demod hardware.
Key Access:
Det/Demod
is not available unless AM or
when
Preset Preset Type
,
Demod
, ,
Alignments Auto Align
,
Align Now All
,
Demod
, .
Off
when the
Chapter 2