Glossary of DVB Terms, Explanation and definition

Glossary of DVB Terms

What is DVB?

The DVB standard contains a whole family of digital television standards. For example, DVB-H is a standard that only works on mobile device platforms. (Glossary of DVB Terms)

Standards under the general name DVB cover all methods of signal transmission: mobile, terrestrial, cable, terrestrial, satellite, and even IPTV. In these communication environments, information packets are transmitted at high levels, which provide decoders (devices) with important information. Such as the number of packets in the current stream, stream type, and other metadata.


Glossary of DVB Terms

BASEBAND is a complete unmodulated television signal that includes all components of the image signal and audio subcarriers modulated by audio signals (Fig. 1). The width of its spectrum depends on the transmission standard and does not exceed 10 MHz.

BAT (Bouquet Association Table) is an optional DVB table with descriptions of services included in one bouquet (a group of services that can be sold as a single product). Always has PID 0011.

BER (Bit Error Rating) - the ratio of the number of erroneous bits in the stream to the total number of bits.

CI (Common Interface) is a PCMCIA interface built into receivers for connecting external modules. It is currently used in receivers equipped with a standardized DVB descrambler to connect external CA modules.

DiSEqC- a group of protocols for the interaction of the receiver with external devices. To transmit 0 and 1, these protocols use certain combinations of a 22 kHz signal and a pause. Switches and positioners are now available with DiSEqC support. When specifying a protocol version, manufacturers do not always follow the DiSEqC specifications, and it is impossible to reliably determine the capabilities of the protocol from the specified version.

However, most commonly DiSEqC 1.0 refers to the version that controls switching between two or four converters, DiSEqC 1.1 controls switching between eight converters, and DiSEqC 1.2 controls the standard DiSEqC positioner. Versions 2. x - as a rule, "assign" to DiSEqC protocols that control specialized external devices, main positioners with additional functions.

ECM (Entitlement Control Message) - contains the data necessary for decrypting information by the conditional access module.

EIT (Event Information Table) - SI table. It contains a list of events related to each thread and the characteristics of those events. The DVB standard defines 4 types of EIT tables.
1. EIT Actual Present/Following - contains information about the current and next events of the received stream. This table is mandatory and has been assigned PID 0x0012.
The rest of the EIT tables are optional.
2. EIT Other Present/Following - contains information about the current and subsequent events in other transport streams of the network.
3. EIT Actual Event Schedule - contains a detailed list of events of the received stream in the form of a schedule covering more distant events.
4. EIT Other Event Schedule - contains a list similar to the previous one, but for other network flows.

EMM (Entitlement Management Message) - contains information about the volume of paid services provided to a particular subscriber or group of subscribers. Used to update information about the terms of subscription to paid channels or rights to receive Pay-Per-View services.

FEC (Forward Error Correction) is a parameter that determines the level of redundancy during coding in accordance with the Viterbi system used to improve the noise immunity of the stream. The level is indicated by a fraction, which is the ratio of the number of useful bits to the total number of bits. So, the value of FEC 3/4 means that there is 1 control bit per 3 useful bits in the stream. The maximum redundancy level currently used in satellite television is 1/2, and the minimum is 7/8. The specific level is selected depending on the width of the radio channel and the power of the satellite transponder.

NIT (Network Information Table) is a mandatory SI/PSI table. Contains information about the coordinates (parameters of transponders) of other transport streams in the network. Always has PID 0x0010. There are two flavors of the NIT table, Actual and Other. The first one is mandatory for DVB transport streams and contains information about the parameters of the network to which this stream belongs. The second is optional. It contains the same information about other networks.

CAT (Conditional Access Table) is a mandatory PSI table. Allows decoders to locate EMM messages. Always has PID 0X0001.

PAT (Program Association Table) is a mandatory PSI table. Contains a list of all programs carried in the transport stream, as well as the PIDs of the PMT tables related to these programs. Always has PID 0x0000.

PCI (Program Specific Information) is a set of service tables necessary for demultiplexing the transport stream and restoring the required program by the decoder. According to the DVB standard, PSI tables include PAT, CAT, PMT, and NIT.

Numbers that define the addresses of elementary streams in the total transport stream received from the satellite. Information about the location of the elementary streams is transmitted as part of the transport stream. All modern digital receivers have the ability to automatically find the necessary PIDs. However, some digital program providers use PIDs that are not part of the DVB standard, and receivers are not able to automatically allocate the desired streams. In such cases, manual entry of PIDs, provided in many receivers, can help.

PMT (Program Map Table) is a mandatory PSI table. Determines the PID values ​​of the elementary streams of all components of one program (service).

QPSK (Quadrature Phase-Shift Keying) - quadrature phase-shift keying. A type of modulation that uses two-phase states (0 and 1800) of two carriers shifted relative to each other by 900. Allows one symbol to transmit 2 bits of information. Used in digital satellite broadcasting.

RGB (Red, Green, Blue) - separate transmission of the three original color components of the video signal - red (R), green (G), and blue (B). An RGB input is available on some modern TVs

RST (Running Status Table) is an optional service DVB table. Contains information about changes in the schedule of events. Allows broadcasters not to retransmit the entire EIT table when changes occur. RST is assigned PID 0x0013.

A SCART connector is a 21-pin low-frequency connector used to connect external devices, most commonly a TV, VCR, and decoders. Pin assignments in different SCART connectors can be different. In some cases, the nature of the signals at the terminals of the connector is determined by software, through the menu of the receiver.

SI table. Contains characteristics of programs and services available on the network. This table is assigned PID 0x0011. The DVB standard provides for two types of SDT tables - Actual and Other. The first one, mandatory, contains descriptions of programs (services) transmitted in this transport stream. The second contains descriptions of programs (services) transmitted in other transport streams of the network.

SI (Service Information) is a set of tables containing information about programs and services transmitted over the network. SI necessarily includes tables TDT, NIT, SDT, and EIT.

S-Video (Super-Video) is a video signal transmission standard that provides for separate transmission of luminance (Y) and chrominance (C) signals formed according to the PAL standard. Some TVs and quality VCRs have S-Video inputs.

ST (Stuffing Table) is an optional DVB-table containing commands for the complete replacement of tables, which were partially rewritten at the headend of the network rebroadcasting the stream.

This allows you to maintain the previous sequence of presentation of data in the table. Has PID 0x0014. SPDIF (Sony/Philips Digital Interface) is a standard digital audio transmission format. Allows you to transmit audio without converting it to analog form. Transmission can be via radio frequency or optical interface. The most common is radiofrequency. In this case, an RCA connector and a coaxial cable are used.

TDT (Time and Date Table) is a mandatory SI table. Contains information about the time and date of the transfer of services. A Universal Time Coordinated (UTC) value is passed, which can be adjusted to match the time zone before being displayed. The constant PID of this table is 0x0014.

TOT (Timing Offset Table) - this table contains the universal time and date, as well as the difference between universal and local time for different geographical zones. The PID of this table is 0x0014

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