Operating instructions

LOCAL OPERATION
3-43
Modulation generators
Set up one or both of the modulation generators for the required frequency, level and shape by
using the soft keys and data input keys. When these and the de-emphasis filter are set to the
required settings press the [Return] key to restore the
RECEIVER TEST menu.
Modulation frequency and level
The frequency range and level must not exceed the following limits:-
Modulating freq. range 20 Hz to 20 kHz
AM depth range 0 to 99% total sum of
active modulation sources
FM deviation range 0 to 75 kHz total sum of
active modulation sources
To enable or set up the modulation generators press the [Mod Gen] key. The screen and menu
shown in fold out diagram (4-2) will be displayed.
Set up the modulation generator(s) for the required frequency and output level by using the soft
keys and data input keys:-
[Gen 1/Gen 2] to select MOD1, then, [FREQ][n]....[n][kHz/Hz]
[LEVEL][n]...[n][kHz/Hz]
then [Gen 1/Gen 2] to select MOD2 if required,....[.../Hz]
Frequency and level increment
The FREQ [×] and [Ø] and the LEVEL [×] and [Ø] keys can be assigned to the modulation
generator frequency and level. See Incremental adjustments which starts on page 3-68.
Modulation generator state
Either or both generators can be switched off to suit the test requirement. To disable a generator,
first select it using the [Gen 1/Gen 2] key. Repeated presses of the orange [ON/OFF] function key
will disable or enable the selected generator.
Note that the modulation generators are also used as AF generators to provide a
modulation source in the Tx TEST mode.
If both AF generators are set to
ON in the Tx TEST mode, switching to Rx
TEST mode will show both modulation generators to be
OFF.
Either or both generators can be set up and turned on within the Rx TEST mode.
The frequency, level and shape settings of their last use in the Rx TEST mode will be retained
within the Rx TEST mode setup. These settings will be effective when the generators are
switched to ON in the Rx TEST mode. Their use as audio generators in the Tx TEST mode will
then be disabled.
Modulation generator shape
The shape of the output waveform from each modulation generator can be set to either sine or
square wave. To change the output waveform from a generator, first select it using the [Gen
1/Gen 2] key. Repeated presses of the [Shape] key will toggle between sine or square wave.
Modulation generator level locking
Pressing the [Lock] key locks the output level of the two modulation generators to the same level.
The unselected generator locks to the level of the selected generator.