Technical data

DOC-01-TELAS-CRG-4 ASTi ACE Studio Components Reference Guide Rev.M
4 Copyright © 2014 Advanced Simulation Technology inc.
2.1. AmpMod
Summary: The Amplitude Modulator component generates a carrier signal whose
amplitude is controlled by a modulating signal. This is useful for general warning
tones (e.g. Radar Warning Receivers) that require dynamic control. Complex
warning tones can be generated when the amplitude modulator is used with a Pulse
component.
Description: The amplitude modulator provides a signal multiplication capability
between two signals, a carrier waveform and a modulating envelope.
The carrier waveform is the external signal source that is connected to the carrier
input parameter. The CarrOffset input parameter is an offset value that is added to
the amplitude of the carrier waveform prior to modulation. If no signal source is
connected to Carrier and Carrier Offset is 0, the amplitude modulator does not
generate an output signal. If no signal source is connected to Carrier and Carrier
Offset is not 0, the amplitude modulator will use the offset value as a dc carrier
(offset).
The modulating signal is the external signal source that is connected to the
ModSignal input parameter. Typically, the modulating signal source is a square
wave or pulse; however, any signal type may be used. The ModOffset input
parameter is the offset value that is added to the amplitude of the modulating signal
before the lag filter is applied. The modulation signal can thereby be offset from
zero to allow for control of the modulation depth. The modulation offset should be
1.0 to provide a full depth of modulation from a square or sinusoidal source. This
assumes the gain of the originating signal is set to 1.0, in which case it will swing
between -1.0 and 1.0, hence the need for a 1.0 offset. The Modulator input flag
controls whether the modulating signal is applied to the carrier. If not signal source
is connected to ModSignal, the amplitude modulator does not modulate the carrier
signal.
The FilterFreq internal parameter determines the filter constant for the lag filter,
which filters modulating signal. This lag filter softens the edges which occur when
square wave modulating a sine wave. The filter constant determines the effective
slew rate of the modulating signal.
The Gain input parameter controls the amplitude of the playsound output. When the
gain is less than or equal to 0, the amplitude modulator component does not output
a signal.
Note: The Lag filter is an a-rate function, not a k-rate function.
Audio Inputs
Carrier-
Signal
Type Default Value
audio n/a
Description: The carrier signal whose amplitude is modulated.
CarrOff-
set
Type Default Value
float32 1.0
Description: Value added to the carrier signal prior to modulation.
If no external variable is connected to ModOffset, the offset scale
factor is used; otherwise, the offset is the scale factor times the out-
put result of the external variable.
Modifier: Multiply
Modifier_default: 0.0
Range: 0.0 - 1.0
Gain
Type Default Value
float32 1.0
Description: Amplitude gain of the waveform. If no external vari-
able is connected to Gain, the value of the scaler is used.
Modifier: Multiply
Modifier_default: 0.0
Range: 0.0-Inf
Modulat-
ingSignal
Type Default Value
audio n/a
Description: The modulating signal whose amplitude controls the
amplitude of the output signal. It passes through a lag filter to round
any sharp edges (as a square wave or pulse would produce) before it
is applied to the carrier signal.