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SDM-300L3 Satellite Modem
Open Network Operations
10.4.1
Description of D&I Operation
The main features of the D&I option are as follows:
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10.4.1.1
Data Interface
Data interface contains transformer
parameters and dejitter. This is compatible with AT&T Digital Speech Interpolation
(DSI) service. Data inputs and outputs named are listed below:
The system is frequently used with the drop receive data output signal (DRD
looped to feed the insert send data input signal (ISD-A, -B). This is accomplished at the
far end of any redundancy switching in order to allow transmit and receive chains to be
switched independently. The zero substitution codes (Alternate Mark Inversion [AMI],
B8ZS, and HDB3) are user
A data loopback function on the insert data is available in this section. This enables the
user to determine that the T1 or E1 data parameters correctly match those of this
interface. The drop data is always hard
10.4.1.2
Transmit MUX
The data stream is TX MUX with a 1/15 overhead channel and the resultant information
rates are interfaced to the Mod/Demod/Coder sections of the modem. A phase-locked
loop generates the output clock (with overhead), using the input clock as a reference. The
input clock is normally the recovered clock from the data interface. If a valid input signal
is not present, the interface falls back to a 10
modem, and will transmit a valid IESS-308 framing pattern. If this occurs, the link will
remain open at the far end and a fault will be signaled.
Data interface
Transmit MUX
Receive DEMUX
ESC
Backward Alarm
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Drop send data input A and B (DSD-A and DSD-B)
Data Inputs
Insert send data input A and B (ISD-A and ISD-B)
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Drop receive data output A and B (DRD-A and DRD-B)
Data Outputs
Insert receive data output A and B (IRD-A and IRD-B)
selectable during configuration.
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balanced data interfaces that support CCITT G.703
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wired into loopback.
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accuracy reference clock generated in the
-5
10–11
Revision 1
MN/SDM300L3.IOM
A, -B)
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