Listening (Audio Mode) - Selcom ST 400 Cayman Operating Manual

2.5. Listening (AUDIO mode)

The AUDIO mode is primarily intended for analysing target responses by listening to the
demodulated signal output. This should give the operator ample information to identify the
response type.
To switch from SEARCH to AUDIO, press
head will then go off, and AUDIO led will light
When the AUDIO mode is on, the device status will be displayed on the antenna module as
described in Table 2 below.
Table 2
legend colour
POWER red
TUNING yellow
AUDIO yellow
INPUT white
LEVEL 3
*Upon switching to AUDIO, none of the TUNING bar segments are lit, which corresponds
to #0 frequency combination.
The ST 402 Cayman NLJD makes it possible to listen to demodulated signals while probing
with six different frequency combinations. Each combination, indicated by LEDs on the TUNING
bar, is suited to deal with a particular category of nonlinear objects. Upon activation of the AUDIO
mode, frequency combination #0 is set by default; it is meant for probing semiconductor content
and, as a rule, gives good results in identifying active radio-transmitting and sound-recording
devices.
Frequency combination #1 is used to analyse return signals from MOM (metal/oxide/metal)
structures.
The remaining four combinations are auxiliary. Their use is advised when responses have been
observed in the SEARCH mode on the red INPUT LEVEL bar, yet probing with combination #0
has rendered no definitive findings.
Table 3 shows correspondence between frequency combinations and responses observed in
the SEARCH mode.
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OPERATING MANUAL
light indication
continuous
blinking
continuous*
continuous
varying numbers of
lit LEDs
. The SEARCH led (5, Fig. 4) on the antenna
up (6, Fig. 4).
meaning
The antenna module is powered properly.
The battery is discharged and needs to be
replaced.
The 5-segment bar displays the selected
probing frequency combination.
AUDIO mode on.
The 16-segment bar displays the levels
of returned signals. Note: in the AUDIO
mode this gauge bar shows a sum total of
responses, regardless of their type.