Appendix D. Theory Of Operation; Rf Signal Conversion - Comtech EF Data CSAT-5060 Installation And Operation Manual

Appendix D. THEORY OF OPERATION

This appendix contains a general description of the theory of operation for the
CSAT downconveter and upconverter sections. The CSAT can be used for
SCPS/MCPC, DAMA, and TDMA, as well as for full transponder HDTV and
analog TV, applications.
The description is for the standard 50W transceiver. In all models, the downconverter and
upconverter local oscillators are independently synthesized to allow simplex or duplex operation. In
order to minimize complexity, they share a common power supply, an internal high stability 10 MHz
reference oscillator, and the Maintenance and Control (M&C) unit.
The downconverter section operates in the frequency range of 3400 to 4200 MHz,
with a temperature compensated gain of 45 dB. This high level of gain provides
an IF output signal level of +13 dBm at 1 dB of gain compression. This provides
the capability to handle longer modem cable runs, or fan out for splitting networks
without requiring additional line amplifiers.
The upconverter section operates over a frequency range of 5845 to 6425 MHz
with a temperature compensated gain of 74 dB. The RF output level is +47 dBm
minimum at 1 dB gain compression over the operating temperature range.
The phase noise performance of both the upconverter and downconverter sections
exceeds the Intelsat phase noise mask for IBS and IDR services by 6 dB. This
allows phase dependent demodulators to provide the best possible performance.
The close-in phase noise is also very low making the converter ideal for low data
rate applications such as DAMA hub earth stations.
An auto select EIA-232 or EIA-485 pin out is available in the circular COM
connector on the exterior of the chassis. All configuration control, status retrieval
and unit adjustments are available as ASCII commands through this interface.
D.1 RF Signal Conversion
D.2 Monitor & Control
D-1
D-2
D-4