Comtech EF Data SNM-1010L - Manual (Page 248)

SNM-1010L Data/Control Modem Revision 0
Specifications MN/SNM1010L.OM
The modem provides a synthesizer reference on the center pin of the L-Band output
connector. The signal is 10 MHz with a stability of
± 0.01 ppm. @ 0.0 dBm,+3, -1 dB.
B.3.18 Control and Monitor
The modem provides an FSK signal for M&C of the SierraCom BUC. An optional plug-
in card is OK.
B.3.19 Current Sense
The modem senses the magnitude of DC current delivered to the ODU and provides
programmable minimum and maximum current thresholds. An alarm is produced when
the sensed current to the ODU either falls below the minimum programmed threshold or
exceeds the maximum-programmed threshold.
B.3.20 Burst Mode Modulator Specifications
The burst mode modulator is used for TDMA transmission using the inbound control
channel. Burst mode is only used while the Data/Control Modem is operating in the
Control mode.
B.3.20.1 Transmit Preamble
In Burst mode, when RTS transitions from false to true, the modem turns On the RF
carrier and generate a burst preamble with the following characteristics:
At the end of the preamble, the modulator causes CTS to transition from false to true.
This signals the baseband equipment to begin sending data. The RF carrier remains On
until RTS transitions back to false.
B.3.20.2 Transmit Packet
| 96 symbols | 352 symbols | 31 symbols |
| | | |
| CW
| BIT TIMING | UNIQUE WORD |
Channel contents:
CW: I and Q channels contain all 1’s
Bit
Timing: I: 1010…
Q: 1010…
Unique Word: I: 000 0010 0011 1010 1001 0111 1001 1011
Q: 000 0010 0011 1010 1001 0111 1001 1011
*Note: Bit Timing and the Unique Word is BPSK and uncoded.
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