User's Manual

RVP8 User’s Manual
October 2005
TTY Nonvolatile Setups
3–31
A two-tone simulation will be produced when the RVP8 is setup in dual-receiver
mode. The pulse will be the sum of two transmit pulses at the primary and secondary
intermediate frequencies. To make the simulation more realistic, the two signal
strengths are unequal; the primary pulse is 3dB stronger than the secondary pulse.
Frequency span of simulated burst: 27.00 MHz to 32.00 MHz
The simulated burst responds to AFC just as a real radar would. The frequency span
from minimum AFC to maximum AFC is given here.
3.2.6.1 AFC Motor/Integrator Option
The question “AFC Servo– 0:DC Coupled, 1:Motor/Integrator” 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 needs to be overcome.
The DC-Coupled AFC loop questions (changes shown in bold) 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
and 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
Notice that the physical units for the feedback slope and slew rate limits are different
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; hence D-Units are used directly.
The above example illustrates typical values that might be used with a
Motor/Integrator servo loop. The feedback slope of 1.0 D-Units/KHz means that a
frequency error of 100KHz would produce the full-scale (100 D-Units) AFC output.
But this is modified by the minimum and maximum slew requests as follows:
S A zero D-Unit output will always be produced whenever AFC is locked.
S When AFC is tracking, the output drive will always be at least 15 D-Units.
This minimum non-zero drive should be set to the sustaining drive level of the
motor actuator, i.e., the minimum drive that actually keeps the motor turning.
S When AFC is tracking, the output drive will never exceed 90 D-Units. This
parameter can be used to limit the maximum motor speed, even when the
frequency error is very large.