LCN--逻辑频道号

LCN在欧洲机顶盒用得很多，很多人用来作为节目排序的准则。一般来说在一个实际网络中LCN是唯一的，它在NIT表中，Descriptor Tag value为0x83。

 Signalling Specifications for DTT deployment in Portugal.pdf描叙如下：

logical_channel_descriptor{
  descriptor_tag //8 uimsbf
  descriptor_length //8 uimsbf
  for (i=o; i<N; i++){
    service_id //16 uimsbf

    visible_service_flag //1 bslbf
    reserved //5 bslbf
    logical_channel_number //10 uimsbf
  }
}

NORDIG NorDig-Unified_ver_2.1版本中LCD V1是这样描叙的：

logical_channel_descriptor(){
descriptor_tag //8 uimsbf
descriptor_length //8 uimsbf
for (i=0;i<number_of_services;i++){
service_id  //16 uimsbf
visible_service_flag  //1 bslbf
reserved   //1 bslbf
logical_channel_number  //14 uimsbf
}
}

descriptor_tag还是0x83。

 NORDIG还有另外一个版本：

Syntax No. of bits Identifier
Logical_channel_descriptor(){
descriptor_tag //8 Uimsbf
descriptor_length //8 Uimsbf
for (i=0;i<N;i++){
channel_list_id //8 Uimsbf
channel_list_name_length //8 Uimsbf
for (i=0;i<N;i++) {
char// 8 Uimsbf
}
country_code //24 Uimsbf
descriptor_length //8 Uimsbf
for (i=0;i<number_of_services;i++){
service_id //16 Uimsbf
visible_service_flag //1 Bslbf
reserved_future_use //5 Bslbf
logical_channel_number //10 Uimsbf
}
}
}

descriptor_tag为0x87.