Frequency Modulation (Vco) Menu - Ametek 7124 Instruction Manual

Chapter 5, FRONT PANEL OPERATION

5.3.13 Frequency Modulation (VCO) Menu

5-24
FILTER CONTROL
The amplitude modulation control signal can be filtered by a simple digital low-pass
FIR filter before being applied to the oscillator, which can be useful for eliminating
noise or glitches on the modulating signal. This control adjusts the filter; when set to
0 the filter is turned off; as the number is increased, increased filtering is applied.
AM ENABLED
This control turns the amplitude modulation control on and off
AM SOURCE
This control determines the source of the signal used to control the oscillator
amplitude. It has two settings, as follows:
ADC 1
The control signal should be applied to the ADC1 auxiliary input. The
CENTER VOLTAGE and VOLTAGE SPAN controls are active.
EXT REF
The control signal should be applied to the external reference channel (either
TTL or analog inputs on either the main console or the 7124 RCU). Because the
reference channel internally generates a fixed signal amplitude that is used as the
control signal for the amplitude modulation, the CENTER VOLTAGE and
VOLTAGE SPAN controls are inactive.
Pressing the Previous Menu key returns control to the Oscillator Menu.
When the Oscillator menu is displayed, pressing a key adjacent to the Frequency
modulation (VCO) item accesses the Voltage Controlled Oscillator menu, which is
shown in figure 5-17.
Figure 5-17, Voltage Controlled Oscillator Menu
The Voltage Controlled Oscillator menu has seven controls affecting the instrument's
internal oscillator. Changes to the setting of the controls can be made by using the
adjacent keys.
When the VCO is enabled, the internal oscillator's output frequency can be
modulated by a signal applied to the ADC1 auxiliary input. The controls operate as