Wegener Communications UNITY 4600 - Manual (Page 20)

General Information
14 800032-01 Rev. G www.wegener.com
PMT Program Map Table. A PSI table within an MPEG transport stream which cross-references
a program (or programs) against all the PIDs that bear its component streams (such as
audios, video, DPI, PCR, etc.). IRDs need this table to decode the compressed
components of that program.
Presets Table A non-volatile table of unit presets. This table is used for either automatic recoveries or as a
shorthand method to quickly reconfigure the unit. The presets table may be programmed at
the factory and edited by the customer, either locally or via network control.
Program A single media stream (combination of audio, video, data, etc.) tied to a common time base.
Program Number A numerical code representing a program.
PSI Tables A group of information-bearing tables, each borne by well-known PIDs, regularly
transmitted in the transport stream. See also “PAT” and “PMT”. Also, ISO 13818-1 gives a
thorough description of these and other Tables.
PTS Presentation Time Stamp. A marker signal associated with audio and video streams within
a program conveyed in MPEG transport stream. This signal allows the audio and video to
be presented in synchronism to each other.
RAM Random access memory. A general term for all volatile memory types out of which
application software executes and into which its variables, state information, and messages
are stored. RAM is also used to designate the volatile storage used by the Transport
Demux and decompression devices.
RF Radio frequency
Service Descriptor Service Descriptors are text entries in the Service Descriptor table (SDT, defined per a DVB
standard). Service Descriptors are used to give text names to the Programs within transport
streams.
Service settings That part of the Unit Settings which allow for the local detection, decompression, and output
(or "display") of a program's services.
Setting,
Last Commanded
The most recent Unit Setting requested by a user (local or network) command. This value is
non-volatile.
Setting,
Last Successful
The most recent Unit Setting, which is NOT a Temporary Setting, at which the IRD was able
to deliver services while free of alarms. This may also be the Last Commanded setting or it
may be the attempted (Transient) setting at which auto-recovery was successful. This value
is non-volatile.
Setting, Permanent That non-volatile Unit Setting which the IRD will attempt, if in Normal Operation, after a unit
reset. This will be the Last Commanded setting unless, since that command was issued,
the IRD had executed an Auto-Recovery and successfully acquired at one of the Preset
settings. In other words, the Permanent Setting is the most recent of the Last Commanded
and Last Successful Settings.
Setting, Temporary A special volatile unit setting with a timed expiration period. The command to invoke this
special setting and the subsequent success of the IRD to find services at this setting does
not affect the non-volatile value of the Last Commanded or Last Successful Settings. Also,
if the compliant IRD receives a command to change its Permanent Setting while in a
Temporary Setting, the Temporary Setting will not be aborted, but the new Permanent
Setting will be recorded in NVRAM as the Last Commanded setting and the Permanent
Setting pointer will refer to that.
Setting, Transient A volatile Unit Setting used for immediate acquisition of services. Transient settings are
either Temporary settings (see above) or Presets used for attempted acquisition during
Auto-Recovery. If, in the case of Presets, the attempt is successful, those settings become
Permanent Settings.
Term Definition