AP01-HD_rev.09_UK
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4.7.2.
MEASUREMENT BANDWIDTH SETTING
In terrestrial band there are two available bandwidths:
n
(100 kHz) and
w
(1 MHz). In
satellite band there are three:
k
(100 kHz),
n
(1 MHz) and
w
(4 MHz). To select the desired
bandwidth press the
MENU
key, turn the shaft encoder to select “FILTER BW”, press
ENTER
; make your selection turning the shaft encoder and the press
ENTER
to confirm. It
is generally better to use the widest bandwidth since it is less critical, unless there is
interference from close signals (in TV channels, for instance, the stereo audio carrier can be
measured only in “n” band, as otherwise the mono audio carrier would interfere). In case of
doubt, it should be better to check the difference on expanded spectrum mode (see
105H
0).
4.7.3.
USE OF ATTENUATOR
The full-scale value of the instrument depends on the inserted attenuation value. This value
changes in steps between 0 and 60 dB. To control the attenuator, press the
ATT
key, then
turn the shaft encoder. The inserted attenuation value is indicated on the status bar in the
lower part of the screen.
When attenuation is inserted, the instrument considers it and indicates the effective input
value. If the full-scale value is exceeded, the
>
sign appears next to level measure; in this
case it will be necessary to increase attenuation. If, on the contrary, the
<
sign appears, it
means the level is lower than the minimum, therefore attenuation must be decreased. The
instrument carries out automatically these two operations if the attenuator is on automatic
mode (on spectrum-analyzer mode the attenuator can be only manual). In order to activate
the automatic mode, press keys 2nd + ATT.
WARNING
:
Use the manual mode when you have to search the maximum or minimum level through
tuning or any other operation such as pointing of antenna. Many experienced operators
prefer using the attenuator on manual mode, since they can better understand level
variations.
In case you measure pure noise or digital signals, you shall know this kind of signals easily
saturates the input stages, thus you should take into consideration the following:
•
Measures should be carried out, as far as possible, using the attenuator on manual
mode.
•
To verify the input is not saturated, you shall check that the level measure does not
considerably change when you modify the attenuation.
•
The more narrow the measurement bandwidth (w, n, k) is, the greater is the risk of
overload.
PLEASE NOTE:
As in each receiver, in reception band there are many high-level
channels which may produce spurious signals. If the operator does not properly set
the attenuator, in case of automatic measures, some frequency actually without any
channel could be measured at unexpected level.
