Comtech EF Data KST-12000 - Manual (Page 97)

KST-12000 Ku-Band Satellite Terminal Revision 4
Theory of Operation MN/KST12000.IOM
5.4 Synthesizer
The RFT-1200 requires two synthesizers:
• One for the down converter to convert the RF input to a 70 MHz IF output.
• One for the up converter to convert the 70 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.
5.4.1 Specifications
RF Inputs:
Connector Type
Impedance
Input level
10 MHz CMOS square wave, 2300 MHz reference (from
IFLO)
SMA
50
Ω
+7 dBm
RF Outputs:
Connector Type
Impedance
Level
U/C Frequencies 12780 to 13280 MHz
D/C Frequencies 9730 to 11530 (RCV 10.95 to 12.75 GHz)
9730 to 10480 MHz (RCV 10.95 to 11.7 GHz)
10480 to 10980 MHz (RCV 11.7 to 12.2 GHz)
11030 to 11530 MHz (RCV 12.25 to 12.75 GHz)
SMA
50
Ω
+7 dBm
5.4.2 Theory of Operation
The synthesizer module multiplies the 10 MHz reference clock to a variable clock by use
of:
• VCOs
• Loop
filters
• Phase detectors
• Variable divide-down chains
The divide-down chain is controlled by the M&C board through the use of CMOS
signals.
The VCO tuning voltages are sent to the M&C for monitoring, as well as a summary lock
detect fault.
Refer to Figure 5-6 for a diagram of the down converter LO synthesizer. Refer to
Figure 5-7 for a diagram of the up converter LO synthesizer.
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