Motorola OM 2000 Installation & Operation Manual page 20

2 OVERVIEW
In general, OOB data input to the OM 2000 must be in MPEG-2 transport packets.
Data sent to configure, control, and boot the OM 2000 need not conform to MPEG-2
format.
Multiplexing the OOB Data
The packet multiplexer combines OOB data from the Ethernet and serial input ports
into a single MPEG-2-compliant transport multiplex, and then routes this multiplex to
the RF modulator. The multiplexer can also accept input data from special internal
sources (for example, the internal generator for emergency alert messages or for
PID 0 and PID 1 control data) if necessary.
Caution!
The main destination for most OOB data is the RF modulator; however, the
multiplexer can route data to other output destinations. Each input packet stream
can be routed to up to three different output destinations. Table 2-2 lists the available
destinations.
Table 2-2 — Multiplexer output destinations
Destination
RF modulator
Serial data ports
UDP connections over
the Ethernet port
Null port
Because of the number of possible input sources and output destinations, the
OM 2000 relies on a collection of data-handling specifications called PID maps to
support the proper multiplexing and routing of data through the packet multiplexer.
One set of PID maps is defined for each input port to control how the multiplexer
handles packets from those streams. Within the set for a port, a single PID map
controls the handling of one packet stream, and each set includes a default PID map
to control the handling of packet streams having no explicit PID mapping.
10
The aggregate input rate of all data to be combined into the RF
output must not exceed 2.005 Mbps. If the rate is lower than
2.005 Mbps, the multiplexer will add null packets to achieve the
correct data rate. If the aggregate input rate is higher than
2.005 Mbps, the multiplexer will drop packets.
Description
The RF modulator uses QPSK modulation to convert an MPEG-2-
compliant transport multiplex into a 1.8 MHz-wide RF signal with a
center frequency between 1 and 129 MHz. Data directed to this
destination is output from the RF Out and IF Out connectors on the OM
2000 back panel.
Data directed to a serial data port is output as a serial datastream. The
serial data ports are valid destinations only when configured as output or
bi-directional ports.
Data directed to a UDP port is output as a serial datastream. The UDP
connections are valid destinations only when configured as output ports.
A legal UDP port number must be assigned to each connection, and the
IP address of the receiving device must be configured.
The null port is a conceptual destination equivalent to routing a packet to
nowhere (that is, discarding the packet).