User's Manual

Model 1150A DVOR
2-8 Rev. - November, 2008
This document contains proprietary information and such information may not be disclosed
to others for any purposes without written permission from SELEX Sistemi Integrati Inc.
Refer to Figure 2-4. The carrier frequency is generated by a PLL synthesizer, referenced to the precision 200 KHz
signal. A voltage controlled oscillator, or VCO, generates the RF signal. This signal is buffered, and a portion of
the signal fed back to the PLL controller, where it is divided by a programmable divider. The divided output is
compared to the precision 200 KHz reference signal in the PLL controller’s phase comparator. The phase
comparator generates an error voltage signal that is filtered and applied to the voltage control input of the VCO, thus
locking the VCO output frequency to the reference. VOR channel selection is accomplished by changing the divide
ratio of the PLL controller’s divider. This divide ratio is programmed into the PLL controller by a serial port
interface (SPI) located in the audio generator CCA. The output of the carrier synthesizer is split and routed to the
carrier phaser, the carrier phase reference, the front panel test port buffer amplifier, and the sideband board in the
synthesizer assembly.
The test port buffer amplifier is located on the 012262 Interface CCA, on the backside of the frequency synthesizer
module. The output of this buffer is attenuated to provide the 10 mW typical carrier frequency output signal
available on the front panel SMA connector. The attenuator also serves to provide a resistive load for the buffer
when no external load is connected to the SMA connector. The 012262 boards serve as an interface with the
Synthesizer (012258) and Carrier (012263) boards to communicate with the system through the backplane. The
012262 board also contains circuitry for sideband generation and power supplies for each of the boards mounted.
The 012258 and the 012263 board each have a 30 pin header for connecting to the 012262 Interface board. The
012258 and 012263 boards are mounted in a housing to provide isolation between the carrier and sideband signals.
DIVIDE BY 50
(200KHz REF)
TEST PORT
BUFFER
CARRIER
AMPLIFIER
CARRIER
LOOP
CONTROLLER
LOOP FILTER
VCO AND
BUFFERS
AUDIO GENERATOR
SPI BUFFER
FREQ/2560
DIVIDER
From Audio
Generator
FRONT
PANEL TEST
POINT
CARRIER MEAN
AND DYNAMIC
PHASER
PHASE
DETECTOR
VOR SYSTEM
CARRIER
AMPLIFIER
(EXTERNAL)
VOR SYSTEM
CARRIER
OUTPUT
PHASE
SHIFTER AND
BUFFERS
USB BUFFER
AMPLIFIER
USB
QUADRATURE
MODULATOR
CVOR/DVOR
MODE
SELECT
DIRECT
DIGITAL
SYNTHESIZER
FREQ/2560
DIVIDER
USB
DETECTOR/
BUFFER
AMPLIFIER
USB RF
OUTPUT
CARRIER FREQ
COUNTER
OUTPUT
10 MHz Ref
TCXO
LSB BUFFER
AMPLIFIER
LSB
QUADRATURE
MODULATOR
FREQ/2560
DIVIDER
LSB
DETECTOR/
BUFFER
AMPLIFIER
USB
DETECTED
OUTPUT
USB FREQ
COUNTER
OUTPUT
LSB FREQ
COUNTER
OUTPUT
LSB RF
OUTPUT
LSB
DETECTED
OUTPUT
Figure 2-4 Synthesizer Block Diagram