SDM-309B Satellite Modem
M&C and Interfaces
MN/U-SDM309B Rev. #
4-4–25
4.2.2.2 Data Interface
The module contains transformer balanced data interfaces supporting CCITT G.703
parameters, (compatible with AT&T DSI service) and de-jitter. Data inputs are named
Drop Send Data Input A and B (DSD-A and DSD-B) and Insert Send Data Input A and B
(ISD-A and ISD-B). Outputs are Drop Receive Data Output A and B (DRD-A and DRD-
B) and Insert Receive Data Output A and B (IRD-A and IRD-B). Frequently the system
will be used with the Drop Receive Data Output signal looped to feed the Insert Send
Data Input. This is to be done at the far end of any redundancy switching as this will
allow Transmit and Receive chains to be switched independently. Zero substitution
codes are AMI, B8ZS, and HDB3 are user selectable during configuration.
A data loop back function on the "Insert" data is available in this Section so that the user
may determine that his T1, or E1 data parameters correctly match those of this interface.
The "Drop" data is always hard wired into loopback.
4.2.2.3 Transmit Multiplexer
The data stream is multiplexed 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 no
valid input signal is present the interface will fall back to a 10-5 accuracy reference clock
generated in the modem and transmit a valid IESS-308 framing pattern. This will keep
the link open to the far end. A fault will be signaled if this happens.
The transmit data will be replaced with an all ones pattern (Alarm Indication Signal or
AIS) in the event of certain failures, per IESS-308.
As a test mode the transmit data can be replaced with a 2047 pattern. Selecting this over-
rides AIS. Only user data bits are replaced with the pattern, the Engineering Service
Channel including framing and alarms will operate normally.
The composite multiplexed data stream is normally fed to the modem for further
processing (scrambling and K7 Viterbi encoding). The composite data stream may be
looped back at this point as a test function called "Interface Loopback" provided that the
transmit data rate matches the receive data rate. This allows the customer to test virtually
the entire interface as the ESC is looped to itself through the Demultiplexer (Demux).
User data also passes through the a Plesiochronous buffer in this mode, so this may also
be checked.
4.2.2.4 Receive Demultiplexer
Receive data including overhead is fed into the demultiplexer for processing. This circuit
checks and synchronizes to the frame pattern and separates the user data from the ESC
channel. If the Demux is receiving a correct signal and synchronized, it will signal the
modem that the multiplex system is locked ("Muxlock") and passing data . This is
Summary of Contents for SDM-309B
Page 7: ...Preface SDM 309B Satellite Modem iv Rev 0 This page is intentionally blank ...
Page 13: ...Table of Contents SDM 309B Satellite Modem x Rev 0 This page is intentionally blank ...
Page 16: ...SDM 309B Satellite Modem Introduction MN U SDM309B Rev 1 1 3 Figure 1 1 SDM 309B Modem ...
Page 18: ...SDM 309B Satellite Modem Introduction MN U SDM309B Rev 1 1 5 Figure 1 3 Modular Construction ...
Page 25: ...Introduction SDM 309B Satellite Modem 1 1 12 MN U SDM309B Rev ...
Page 28: ...SDM 309B Satellite Modem Installation MN U SDM309B Rev 2 2 3 Figure 2 1 Rear Panel View ...
Page 34: ...SDM 309B Satellite Modem Operation MN U SDM309B Rev 3 3 Figure 3 1 Front Panel View ...
Page 47: ...Operation SDM 309B Satellite Modem 3 16 MN U SDM309B Rev Figure 3 2 Menu Tree ...
Page 48: ...SDM 309B Satellite Modem Operation MN U SDM309B Rev 3 17 Figure 3 3 Menu Tree ...
Page 49: ...Operation SDM 309B Satellite Modem 3 18 MN U SDM309B Rev Figure 3 4 Menu Tree ...
Page 50: ...SDM 309B Satellite Modem Operation MN U SDM309B Rev 3 19 Figure 3 5 Menu Tree ...
Page 51: ...Operation SDM 309B Satellite Modem 3 20 MN U SDM309B Rev Figure 3 6 Menu Tree ...
Page 52: ...SDM 309B Satellite Modem Operation MN U SDM309B Rev 3 21 Figure 3 7 Menu Tree ...
Page 53: ...Operation SDM 309B Satellite Modem 3 22 MN U SDM309B Rev Figure 3 8 IF Loopback ...
Page 54: ...SDM 309B Satellite Modem Operation MN U SDM309B Rev 3 23 Figure 3 9 RF Loopback ...
Page 55: ...Operation SDM 309B Satellite Modem 3 24 MN U SDM309B Rev Figure 3 10 Interface Loopback ...
Page 56: ...SDM 309B Satellite Modem Operation MN U SDM309B Rev 3 25 Figure 3 11 Baseband Loopback ...
Page 71: ...Operation SDM 309B Satellite Modem 3 40 MN U SDM309B Rev Figure 3 12 Menu Tree ...
Page 72: ...SDM 309B Satellite Modem Operation MN U SDM309B Rev 3 41 Figure 3 13 Menu Tree ...
Page 73: ...Operation SDM 309B Satellite Modem 3 42 MN U SDM309B Rev Figure 3 14 Menu Tree ...
Page 74: ...SDM 309B Satellite Modem Operation MN U SDM309B Rev 3 43 Figure 3 15 Menu Tree ...
Page 75: ...Operation SDM 309B Satellite Modem 3 44 MN U SDM309B Rev Figure 3 16 Menu Tree ...
Page 76: ...SDM 309B Satellite Modem Operation MN U SDM309B Rev 3 45 Figure 3 17 Menu Tree ...
Page 77: ...Operation SDM 309B Satellite Modem 3 46 MN U SDM309B Rev ...
Page 88: ...SDM 309B Satellite Modem M C and Interfaces MN U SDM309B Rev 4 4 11 Figure 4 4 IBS Fault Tree ...
Page 89: ...M C and Interfaces SDM 309B Satellite Modem 4 4 12 MN U SDM309B Rev Figure 4 5 Jumper Table ...
Page 127: ...SDM 309B Satellite Modem Theory of Operation MN U SDM309B Rev 5 5 3 Figure 5 1 Modulator Card ...
Page 151: ...Maintenance SDM 309B Satellite Modem 6 6 6 MN U SDM309B Rev Figure 6 3 Typical Eye Patterns ...
Page 177: ...SDM 309B Satellite Modem Data Rates and Filters MN U SDM309B Rev A 9 ...
Page 235: ...External Channel Unit SDM 309B Satellite Modem C C 28 MN U SDM309B Rev Figure C 13 Menu Tree ...
Page 236: ...SDM 309B Satellite Modem External Channel Unit MN U SDM309B Rev C C 29 Figure C 14 Menu Tree ...
Page 237: ...External Channel Unit SDM 309B Satellite Modem C C 30 MN U SDM309B Rev Figure C 15 Menu Tree ...
Page 238: ...SDM 309B Satellite Modem External Channel Unit MN U SDM309B Rev C C 31 ...
