Wegener DTV742, User Manual

Page: 42 / 50

DTV 742 User’s Manual
800057-01 Rev. B 42 wegener.com
3.7 Transport Stream Processing
Refer to ISO 13818-1 for supporting details on the structure of MPEG Trans-
port Streams.
RF Signal
Reception The channel number or carrier frequency must be supplied to the tuner in order
for the unit to derive its Transport Stream from the RF input. This data is used
to set up the tuner module. If carrier acquisition is successful, then the Trans-
port Stream borne in the carrier will be passed to the ASI output.
Input to
Output
Processing The DTV742 has four RF ATSC inputs that the unit processes. Programs are
passed through to the selected ASI output. A program or programs from one
RF input may be routed to one or more ASI outputs. Each ASI output may
receive signals from all RF inputs. However, an ASI output may also be set up
to receive signals from only one RF input.
PSIP
Structure and
Program
Selection Within the transport stream are PIDs carrying tabular information on that
stream. The PAT describes all the programs available. A program number iden-
tifies each program in the transport stream. When a source of data is acquired,
the stream is passed to the internal transport demultiplexer. This circuit then
extracts the PAT and PMT information and provides this information to the
user on the web interface.
3.8 Alarm/Warning System
The alarm and warning system is intended to provide indications to the local
user of a critical failure or imminent failure. See
Table 7: LED Indicator
Descriptions on page 33 for the visual indications.
Alarm
conditions Generally, if the unit is unable (or presumed to be unable) to present output
from a transport stream, then that is an alarm state. The following list defines
all alarms during normal operation (also see
Initialization Failure on
page 41):
1. All inputs missing - no RF input signal detected.
2. RF missing - no RF signal at one or more enabled inputs.
3. RF n PAT missing - PAT missing in a specific RF input stream (RF input
port
n
).
Warning
conditions The DTV742 presents the following warnings when an input transport stream
is missing needed information.
1. PCR missing – An input transport stream does not include a PCR (program
clock reference).
2. PMT missing - An input transport stream does not include a PMT (program
map table).