Modulation Gain - MOGlabs ARF021 Manual

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5.2 Modulation gain

5.2.1 Physical units
5.2.2 Integer representation
The modulation depth is controlled by the "gain" and is set using
GAIN
the command. Each modulation mode (amplitude, frequency or
phase) has a separate modulation gain for individual control, and
can be negative to indicate that the modulation action is inverted.
The gain can be specified either with physical units, or using an
integer representation.
Since firmware v1.6.4 the gain can be specified with physical units,
which corresponds to the modulation achieved at +1V input. Fre-
quency can be specified in MHz, kHz or Hz, phase in degrees or
radians, and amplitude in percentage.
For example, when +1V is applied to the associated modulation
GAIN,1,FREQ,10MHz
input,
GAIN,1,AMPL,-100%
and
Note changing the output power changes the amplitude and hence
the modulation depth as a percentage, so the amplitude gain com-
mand must be issued again to keep the percentage depth the same.
Also, when performing frequency modulation, ensure that the gain be
chosen to ensure that the output frequency stays between 20 MHz
and 400 MHz to prevent unexpected behaviour.
The gain is alternatively specified as a signed 32-bit integer in
either decimal or hexadecimal, with a negative value indicating the
the modulation action is inverted
in the table below.
1
Negative hexademical values are represented using two's complement.
Chapter 5. External modulation
will shift the output frequency by 10 MHz
will bring the amplitude to zero.
1
. The range of gain values is shown