The NIT (Network Information Table) provides information on Multiplexes & Transport streams in a network and information about the network itself.
The combination of the Original Network ID and Transport Stream ID must be unique so each transport stream can be identified in the network. Networks have unique network IDs allocated, utilized as a unique identification code for the Network. An overview of these codes can be found in the ETR_162 or online
Besides the current network it's also possible to send NIT tables for other networks (NIT-other). Identification of these tables is done by using different table_id's The NIT tables that describe the actual network use table_id 0x40, tables for the other networks use table_id 0x41. In most cases, the receiver will store the NIT in the memory to optimize access speed the service. Update of the table indicated by the raising of the version number must be detected to follow the network changes.
TR 101 290
  • The repetition rate must be less than 0.5 seconds.
  • The time between receiving the last byte of the section and the first byte of the next section should be at least 25 ms.
  • The Scrambling Control must have the binary value '00 ' ( umscrambled )
  • Descriptors
    The following descriptors may appear in the NIT :
  • Network_name_descriptor
  • service_list_descriptor
  • stuffing_descriptor
  • satellite_delivery_system_descriptor
  • cable_delivery_descriptor
  • linkage_descriptor
  • terrestrial_delivery_system_descriptor
  • multilingual_network_name_descriptor
  • private_data_specifier_descriptor
  • frequency_list_descriptor
  • cell_list_descriptor
  • cell_frequency_link_descriptor
  • default_authority_descriptor
  • time_slice_fec_identifier_descriptor
  • S2_satellite_delivery_system_descriptor
  • extensie_descriptor
  • user_defined

  • name bits description
    Table ID 8 Indicates to which table this section belongs, in this case NIT-actual = information about the current network (0x40). In the case of NIT-other (0x41) = information on other networks
    section_syntax_indicator 1 Indicates whether a sub-table structure including CRC check is used.
    reserved_for_future_use 1 always binary value '0'
    Reserved 2 always binary value '11'
    Section length 12 The length of the section in bytes. This length starts immediately after this field and includes the CRC.
    Network_id 16 Indicates to which network this NIT belongs.
    reserved 2 always binary value '11'
    version_number 5 Value between 0 to 31.< br />A higher value indicates that the information has changed.
    current_next_indicator 1 This is to indicate whether a section is 'valid now' or 'valid in future'
    section_number 8 Value between 0x00 - 0xFF. Used to indicate the sections of a table. Up to 256 sections
    last_section_number 8 The number of the last section, so the receiver know when the table is completely received.
    reserved for future use 4 always binary value '1111'
    netwerk descriptors length 12 Indicates the total length of the descriptor loop network
    Netwerk descriptor loop
    reserved for future use 4 always binary value '1111'
    transport stream loop length 12 Indicates the total length of the transport stream loop
    transport stream id 16 This 16 bit field indicates the transport stream ID for identification of the transport stream in the network
    original network id 16 This 16 bit field shows the original network id
    reserved for future use 4 always binary value '1111'
    transport descriptors length 12 Indicates the total length of the transport descriptors loop
    transport descriptors loop
    CRC_32 32 Cyclic redundancy check