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SLM-7650 Satellite Modem
Theory of Operation
4.4.3.2.1.9 Drop & Insert
The interface option card provides Drop & Insert (D&I) functional support. The
following table provides definitions for D&I.
Characteristic
Terrestrial Data Rates
Terrestrial Framing
D&I Formats
Satellite Data Rates
Satellite Overhead
D&I Time Slot to Channel
Mapping
Terrestrial Data Interface
Transmit Clock Source
(Drop)
Receive Buffer Clock
Source (Insert)
ESC
Definitions
1544.0 kbps (T1), 2048.0 kbps (E1)
G.732/G.733, G.704
T1 (D4 framing), T1 (Extended Super Frame "ESF"),
E1 (Common Channel Signaling "CCS"), and
E1 (Channel Associated Signaling "CAS")
N x 64.0 kbps ("N" is the number of 64.0 kbps channels)
N = 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 16, 20, 24 (T1 and E1_CCS)
N = 1, 2, 4, 6, 8, 12, 16, 24, 30 (E1_CAS)
1/15 of satellite data rate, per IESS-309
Terrestrial time slots:
T1 = 1 to 24
E1 (CCS) = 1 to 31
E1 (CAS) = 1 to 15 and 17 to 31
Channels: 1 to N (N = Satellite Data Rate ÷ 64 kbps)
Note:
N = 30 (1920.0 kbps) is a transparent mode which disables
time slot to channel mapping.
Drop Channel Assignments: Maps terrestrial time slots to transmit
satellite channels.
Insert Channel Assignments: Maps received satellite channels to
terrestrial time slots.
G.703
Signals Supported:
DDI (Drop Data Input)
DDO (Drop Data Output)
IDI (Insert Data Input)
IDO (Insert Data Output)
Note: Only DDI and IDO are supported on the G.703
un-balanced interface. DDO to IDI internal loop is
supported, when enabled the drop data output is
internally routed to the insert data input.
Transmit clock will reference the terrestrial input data source only.
In addition to the normal buffer clock sources, "Insert Clock" is added
as a selection. If "Insert" is selected as the clock source, inserts will
be applied to the terrestrial data input at IDI and output to IDO. Any
other clock selection will cause inserts to be applied to an internally
generated terrestrial data stream referenced to the selected clock
source and output to IDO.
D&I operates with the IBS Overhead ESC.
4–23
Revision 4
MN/SLM7650.IOM
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