Upconverter; Figure 1-2 Functional Block Diagram Of The Downconverter Section - Comtech EF Data CSAT-5060 Installation And Operation Manual

5 to 25 Watt Model C-Band Transceiver
Introduction
1.2.1 RF S
IGNAL
1.2.1.1 D
OWNCONVERTER
The RF input to the downconverter (Figure 1-3) is in the 3400 to 4200 MHz frequency range at a
typical level of -45 dBm. The input signal is mixed down to the 1110 MHz IF in the first
conversion mixer. High side LO injection is used for this mixing process. It is provided by the
downconverter RFLO synthesizer in the 4510 to 5310 MHz frequency range in 1.000 or 2.500
MHz steps. Both step sizes are automatically selectable.
IF filtering is provided by the 1110 MHz BPF. It is just wide enough to pass the 36 MHz
bandwidth of the desired signal while maintaining more than adequate amplitude and group delay
flatness. At the same time, it is narrow enough to provide the necessary rejection to the image, the
RFLO, and other spurious signals. The second mixer operates at a fixed input frequency of 1110
MHz. It operates with high side LO injection at 1180 MHz provided by the downconverter IFLO
and converts the IF signal down to the 70 ±18 MHz output frequency.
3 4 00 -
4 2 00 M Hz
3 40 0 - 42 0 0 M Hz
CO M M & C 10 M Hz
REFERENCE
Figure 1-2. Functional Block Diagram of the
1.2.2 U
PCONVERTER
The RF input to the upconverter (Figure 1-4) is at 70 ± 18 MHz at a typical level of -35 dBm
which would provide an output power back-off of 8 dB. In operation, the input signal is mixed
up to the 1250 MHz IF in the first conversion mixer operating at a fixed frequency with low side
LO injection at 1180 MHz provided by the upconverter IFLO. IF filtering is provided by the 1250
MHz BPF. It is just wide enough to pass the 36 MHz bandwidth of the desired signal while
maintaining more than adequate amplitude and group delay flatness. At the same time, it is
narrow enough to provide the necessary rejection to any unwanted mixer products, the IFLO, and
other spurious signals.
C
ONVERSION
V A R
A TTEN
RFLO
45 1 0 -
5 3 10 M Hz
Downconverter Section
1 1 1 0 M Hz BP F
IFLO
1 1 8 0 M Hz
1 18 0 M Hz
1-3
Revision 1
MN/CSAT506025.IOM
V A R
A TTEN
7 0 +/ - 1 8 M Hz
P O WER
SUP P LY