Network Technologies ASI-IP-GTW 用户手册

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ASI-IP-GTW User's Manual 
 
 Page 
77 
format. Three versions exist. IGMPv2 is common today but IGMPv3 is 
the next step.  
Meta-data: Meta-data is descriptive data that is "tagged" to a movie or 
audio clip. Meta-data is essential for the broadcaster.  
MPEG2: Moving Picture Experts Group 2. The compression standard 
used today on most satellite and cable TV digital broadcasts.  
MPLS: Multi-protocol Label Switching. A Quality of Service mechanism 
for IP networks that allow IP packets to flow along a predefined path in 
a network, improving the reliability and robustness of the transmission. 
MPTS: Multi Program Transport Streams. Transport Streams that carry 
multiple TV/Radio services. 
Multicast: An IP mechanism that allows transmission of data to 
multiple receivers. A multicast can also have several transmit sources 
simultaneously. In video applications, multicast is typically used to 
distribute a video signal from a central source to multiple destinations. 
NMS: Network Management System. A system used to supervise 
elements in an IP network. When a device reports an alarm, the alarm 
will be collected by the NMS and reported to the operator. NMS systems 
typically collect valuable statistics information about the network 
performance and can warn the operator early. 
PCR: Program Clock Reference. A sampled 27MHz video clock used in 
MPEG2 Transport Streams. The primary purpose of the PCR is timing 
synchronization between transmitter and receiver. 
PSI/SI: Program Specific Information / Service Information. This is 
information tables (meta-data) that is carried in MPEG2 transport 
streams in addition to video and audio. The information carried is 
typically service/program IDs, program names, conditional access 
information etc. 
QAM: Quadrature Amplitude Modulation. A digital modulation type 
that is used for transmission of digital TV signals over cable TV 
networks. Often referred to as DVB-C. 
QoS: Quality of Service. A common term for a set of parameters 
describing the quality you get from an IP network: Throughput, 
availability, delay, jitter and packet loss. 
QPSK: Quadrature Phase-Shift Keying. The digital modulation type 
typically used for transmission of digital TV signals over satellite. Often 
referred to as DVB-S. 
RIP2: Routing Information Protocol v2. A protocol used between 
network routers to exchange routing tables and information. 
RSVP: ReSerVation Protocol. A Quality-of-service oriented protocol used 
by network elements to reserve capacity in an IP network before a 
transmission takes place. 
RTP: Real-time Transfer Protocol. A protocol designed for transmission 
of real-time data like video and audio over IP networks. RTP is used for 
most video over IP transmissions. 
SDI: Serial Digital Interface. Also known as ITU-R BT.656. A 
specification describing how to digitize and transmit uncompressed 
video signals. The typical bit rate of an SDI signal is 270Mbit/s.