Vaisala RVP900 - Page 103

Frequency span of simulated burst: 27.00 MHz to 32.00 MHz
More Information
‣
Automatic Frequency Control (AFC) (page 176)
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Digital AFC (DAFC) (page 50)
5.2.1.1 AFC Motor and Integrator Option
The AFC Servo– 0:DC Coupled, 1:Motor/Integrator question selects whether
the AFC loop runs in the normal manner (direct control over frequency), or with an external
Motor/Integrator type of actuator.
The question AFC minimum slew request:... provides additional control when
interfacing to mechanical actuators whose starting and sustaining friction must be
overcome.
The DC–Coupled AFC loop questions are:
AFC Servo– 0 :DC Coupled, 1:Motor/Integrator : 0
Wait time before applying AFC: 10.0 sec
AFC hysteresis– Inner: 5.0 KHz, Outer: 15.0 KHz
AFC outer tolerance during data processing: 50.0 KHz
AFC feedback slope: 0.0100 D–Units/sec / KHz
AFC minimum slew rate: 0.0000 D–Units/sec
AFC maximum slew rate: 0.5000 D–Units/sec
The Motor/Integrator loop questions are:
AFC Servo– 0 :DC Coupled, 1:Motor/Integrator : 1
Wait time before applying AFC: 10.0 sec
AFC hysteresis– Inner: 5.0 KHz, Outer: 15.0 KHz
AFC outer tolerance during data processing: 50.0 / KHz
AFC feedback slope: 1.0000 D–Units / KHz
AFC minimum slew request: 15.0000 D–Units
AFC maximum slew request: 90.0000 D–Units
The physical units for the feedback slope and slew rate limits are
dierent in the two
cases.
• In the DC–Coupled case the AFC output voltage controls the frequency directly, so
the units for the feedback and slew parameters use D–Units/second.
• In the Motor/Integrator case, the AFC output determines the rate of change of
frequency. The D–Units are used directly.
Chapter 5 – TTY Non-volatile Setups
101