Comtech EF Data CDM-600/600L - Manual (Page 259)

G–1
Appendix G. BUC FSK
COMMUNICATIONS (CDM-600L)
G.1 Introduction
The CDM-600L Open Network Satellite Modem’s modulator includes capability to communicate
with a Block Up Converter (BUC) using an FSK signal multiplexed onto the IF output connector
along with the Tx IF signal, 10 MHz reference, and DC power to the BUC. The M&C implements
commands to control BUC functions and to query the BUC for configuration or status information.
FSK Transmitter
Frequency 650 kHz
± 5 %
FSK Deviation ± 60 kHz nominal (+60 kHz mark)
Deviation Tolerance ± 50 kHz minimum, ± 70 kHz maximum
Output Level -5 to –15 dBm
Start Tone Time 10 ms minimum
Output Impedance 50
Ω
Start Tone 710 kHz
FSK Receiver
Locking Range
Input Sensitivity ± 32.5 kHz
-15 dBm (50
Ω)
Transmission Protocol
Baud Rate
Data Bits
Parity
Stop Bits
Message Rate
BUC Response Time
Maximum Response Time 9600 bps
8
None
1
1 every 40 msec
12 msec, typical
40 msec
Note: If the BUC does not respond within the maximum response time the
IDU should cyclically repeat the command.
On power-up, the Tx carrier is Off until the BUC is commanded to turn the carrier on (unless the
unit is commanded into the power On mode at the factory). The BUC does not allow the carrier to
be turned On unless the PLL is locked, and automatically turns the carrier Off in the event the PLL
goes out-of-lock. If the PLL then comes back into lock, the BUC restores the carrier to the most