Comtech EF Data HPCST-5000 - Manual (Page 173)

High-Power C-Band Satellite Terminal Configurations
Rev. 0 A–3
A.1.2 Synthesizer
The 140 MHz IF terminal requires two synthesizers:
" One for the down converter to convert the RF input to 140 MHz output
" One for the up converter to convert 140 MHz input to the RF output
The purpose of the synthesizer module is to convert the 10 MHz reference signal to a
variable frequency to perform the conversion.
A.1.2.1 Specifications
Refer to Table A-2 for specifications.
Table A-2. Synthesizer Specifications
Parameter Specifications
RF Inputs
Connector type
Impedance
Input level
10 MHz CMOS square wave
SMA
50
#
+7 dBm
RF Outputs
Connector type
Impedance
Level
Frequencies 4592.5 to 5172.5 MHz
SMA
50
#
+7 dBm
A.1.2.2 Theory of Operation
The synthesizer module multiplies the 10 MHz reference clock to a variable clock by use
of a VCO, loop filter, phase detector, and a variable divide-down chain. The divide-down
chain is controlled by the M&C board through the use of three serial signals. A frequency
tripler is then applied to produce the final output.
The VCO tuning voltage is sent to the M&C for monitoring, as well as a lock detect fault.
Refer to Figure A-2 for a block diagram of the LO synthesizer. Refer to Figure A-3 for a
block diagram of the U/C LO synthesizer.