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• AUTO
TUN"~
MODE
Enable full-band scan lock with special function control
code
#3300
(table
3-3).
The monitor scans its specified
frequency range to automatically acquire and tune a
strong input signal within fjve seconds. For faster ac-
quisition, use special function control code #33XY to
limit the scan range to 100 MHz increments. The
minimum input signal level for automatic frequency ac-
quisition is -30 dBm at the antenna port and 0 dBM at
the transceiver port. The word SCANNING replaces the
programmed frequency display. Line 8 displays the ac-
tual input frequency
±
I KHz as shown in the example
in figure 3-10. When tuned, dashes replace the SCANN-
ING display and a dash in the cursor replaces the chan-
nel number. When the input signal is removed, scanning
resumes.
• SCAN LATCH MODE
Select this variation of the auto tune mode, using special
function control code #3400 or 34XY to program and
latch an auto tune frequency. In this mode, the input
signal is acquired and tuned in the same manner as for
auto tune. However, the programmed frequency display
shows the word:
• LATCHED
and a dash under the cursor instead of the preset
number.
The second line on the metering display reads
• PRESS 0 TO RESCAN
If the input signal is removed, the system remains pro-
grammed to the last frequency tuned. When the
operator activates the 0 key, scanning resumes and the
word SCANNING replaces the word LATCHED on the
display. The preset number 0 appears under the cursor.
Also, the CRT omits the second line on the display as
scanning resumes.
The scan latch mode is useful for locating the transmit
frequency of trunked radios.
3.6
MONITOR SECTION
MONITOR
SquelCh
Volume
~19l
... ,
•
0" . . . .
'PM"
Image Opht
OW
HI9h~.
Wide
LOIN
w
N;wow
Delima OuI
BFO
FIGURE 3-15. MONITOR SECTION
3-8
• VOLUME AND SQUELCH CONTROLS
The Volume control adjusts the speaker output level.
The Squelch control located to the left of the Volume
control (figure 3-15) is continuously variable from Off
position (disabled squelch) to a maximum squelch lev(
of
-25
dRm
±
10 dB at the antenna port. When the
Signal Level LED illuminates, it indicates an open posi-
tion (unsquelched). When the LED is not illuminated, it
indicates a closed position (from threshold to tight
squelch).
• OFF-THE-AIR MONITOR
Use the Analyzer's antenna port for off-the-air monitor-
ing. The Analyzer receiver's 1.5 uV sensitivity allows
off-the-air monitoring to measure transmitter frequency
error and deviation to 1000 MHz. Monitor weak signals
with the variable squelch. But for accurate measure-
ment, set them higher to ensure proper signal-to-noise
ratio. More accurate measurements result from using a
higher signal level. The off-the-air monitor function
enables frequent parameter checks to spot system degra-
dation early and reduce service costs. Set Wide band-
width for off-channel signal location or wide band FM.
Set Narrow bandwidth for maximum sensitivity and
selectivity.
• SIGNAL STRENGTH METER
Place the FUNCTION switch in Monitor mode. The
frequency selective signal strength indicator, operates
simultaneously with other monitor functions over the
full input frequency range of the monitor.
It
uses a max-
imum 30 KHz bandwidth around the monitor center fre
quency. At the antenna port, the signal strength in-
dicator operates for input levels from -99.9 dBm to -30
dBm with the Step attenuator in the 0 dB position. For a
non-zero attenuate both limits are increased by the
amount of the attenuation. Measure higher level signals
by inserting loss, using the rotary attenuator. The
displayed measurement compensates for the attenua-
tion.
• FM DEMODULATION
The monitor demodulates FM to 75 KHz peak deviation
in the wide band position and to 5 KHz in the narrow
band position. Selectable highpass and lowpass filter
sections determine the monitor's frequency response
with characteristics as shown in table 3-4. Select band-
width via BW switch or special function control. The
wide band position enables the 5 Hz highpass and 20
KHz lowpass filters. The narrow band position enables
the 5 Hz highpass and 3 KHz lowpass filters. Special
Function overrides the BW switch to enable selection of
any combination of high and low pass filtering as de-
fined in table 3-3.
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