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2-2
Overview
Functional Overview
The primary function of the OM 1000 is to combine multiple OOB data inputs into a single
datastream that is transmitted over the OOB channel as an RF signal. The OM 1000 also
provides serial data communications to transmit and receive baseband digital data over various
serial data ports.
OOB Signal Processing
In converting the OOB data inputs into an RF signal, the OM 1000 performs the following OOB
signal processing functions:
Receives the cable terminal control stream and other OOB data from multiple input
sources.
Multiplexes the information into a single, packet-based, MPEG-2-compliant transport
stream.
Inserts Packet Identifier 0 (PID 0) and PID 1 control streams into the transport stream if
necessary.
Modulates the digital transport stream onto a 1.5 MHz-wide RF carrier using QPSK
modulation.
Upconverts the resulting signal into an RF output with a center frequency in the
71 through 129 MHz range. (An IF output is available for optional external upconversion to
other frequencies.)
Figure 2-2 shows the typical flow of OOB data from the input port(s) through the packet
multiplexer to the RF modulator:
Figure 2-2
OOB data flow through the OM 1000
PID0/PID1 data
(if necessary)
OM 1000 Installation and Operation Manual
RS-232
RS-530
OOB
data
Ethernet
multiplexing
UDP/IP
Message storage
Ethernet
and packet
TCP/IP
generation
RF
Packet
modulation
and upconversion
RF
out
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