Wegener Communications 4600 manual Glossary of Terms and Abbreviations, Compel→, Dpi, Dtmf, Dvb

General Information

1.5 Glossary of Terms and Abbreviations

	Term	Definition
	Ad avail, digital	The opportunity for a local program splicer to insert local content in the MPEG PES streams
		in substitution for “regular” network-distributed programming. The avail is bounded by
		“splice out” and “splice in” points. "Splice points" are seamless insertion points (located for
		the splicer by DPI messages) where the compressed stream may be broken and
		substituted without frame-by-frame interruption of video.
	Ad avail, analog	The opportunity for local users to switch from the network-supplied programming to locally-
		generated content (commercials). This is signaled by use of DTMF tones or closures of cue
		relays.
	Alarm	A condition or notification of a condition that prevents proper Unity 4600 functioning.
	Application Software	The main host software which sets up the unit hardware, runs the process of acquiring
		transport stream sources, sets up and monitors the demux and decompression processes,
		monitors unit operations, and interfaces with the network and local users.
	ASI (or DVB-ASI)	An “asynchronous” bit-serial physical interface for transport streams. Transmitting and
		receiving functions are designed such that the time relationships between all packets and
		their timing references are unchanged.
	Audio Language	Legacy 3-character MPEG descriptor applied to a program’s audio streams. It was
	Descriptor	originally allocated to designate languages, but is now used for generic identification.
	Automated Recovery	The mechanism used when the Unity 4600 is unable to acquire a valid transport stream,
	(or Recovery)	loses network control or detects an invalid control stream, or is unable to deliver the
		required services using its current settings. The unit automatically begins attempting
		operations under "backup" unit settings stored in the presets table until it can return to
		normal operation or is stopped by local user command.
	Boot loader	Software residing in non-writable zone of flash which executes at unit reset. It will verify and
		load the preselected application.
	CA	See "Conditional Access".
	COMPEL→	Wegener's network control software that may be used to manage your Unity 4600 as well
		as other hardware.
	Conditional Access	Wegener’s system for securing the transmitted transport stream from unauthorized access.
		It features distribution of ciphered authorizing messages within a special PID. Upon
		deciphering in secure processors within the IRD, these messages continuously update the
		IRD with the current descrambling key.
	DPI	Digital Program Insert. A special message, borne in an MPEG PID associated with a
		particular program, that signals the boundaries of ad avails.
	DTMF	Dual-Tone Multi-Frequency. Tone signaling system used by the legacy telephone system.
		Tone pairs represented each of the keyboard items 0-9, *, and #. This system may be used
		to control external cueing equipment.
	DVB	Digital Video Broadcast working group. This is a shorthand designation for a group of
		industry standards that provide enhancements in the use of MPEG transport streams. (For
		example, one DVB standard defined the standard way QPSK-modulated carriers would
		convey these streams over satellite world-wide.)
	Eb/N0	Energy-per-bit per Noise density-per-Hertz. This is a unitless ratio that expresses signal-to-
		noise ratio in carrier transmission systems that convey digital data. A quality measurement
		for any such system is the Eb/N0 needed to just convey the digital data within acceptable
		error rates. This is called the “Eb/N0 threshold”.
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