Operating instructions

LOCAL OPERATION
3-33
Occupied Bandwidth
This optional facility is used to evaluated the bandwidth occupied by the output from a transmitter.
The display is a modified presentation of the spectrum analyzer display. For more information
about the Spectrum Analyzer facility refer to the Spectrum Analyzer section of this chapter starting
on page 3-55 .
B5472
Fig. 3-9 Occupied Bandwidth display
The Occupied Bandwidth facility is accessed from the Tx Test mode or from the Duplex Test
mode, by pressing the [Tx Power] soft key and then the [Occ B/width] soft key. The
OCCUPIED
BANDWIDTH screen is then displayed. See fold out diagrams (2.0) and (4.0).
The facility produces a measurement of the occupied bandwidth of a signal from a transmitter by
evaluating the spectral display of the signal. The result of the measurement is shown on the
display as:-
Occ BW nn.nkHz.
The parameters that can be set are:-
[Ref Level} Selects the RF Signal Reference Level setting and allows the value to be set using the
data keys, the variable control or the increment keys. For an accurate result the signal peak should
be within the top 10 dB division.
[O B/W Ratio] Selects the Occupied Bandwidth setting and allows the value to be set using the
data keys or the variable control. The settable range is 90.0 to 99.9%.
[RF Gen on/off] Enables or disables the output from the RF generator within the Test Set. This
signal may be used within the overall test setup and the ON/OFF key is provided for controlling it
without the need to leave the
Occupied Bandwidth facility.
[Centre Freq] Selects the Center frequency setting for the display and allows the value to be set
using the data keys or the variable control. The set value will usually be the RF Carrier Frequency
of the signal being measured.
[Span] Selects the Span setting for the display and allows the value to be set using the data keys,
the variable control or the increment keys. For an accurate result the span setting should be set to
give a display of the signal under investigation that has the obvious extent of the signal remaining
visible with the minimum of the noise floor included. The measurement will only work over the
displayed span, any signal power outside of this will be ignored.
[Res BW] Allows the Resolution Bandwidth of the display to be optimized. Automatic or manual
selection is available.