GB20600-2006
Framing structure, Channel coding and modulation for digital television terrestrial broadcasting system
数字电视地面广播传输系统帧结构、信道编码和调制
GB 20600-2006 is a current mandatory Chinese national standard for Framing structure, Channel coding and modulation for digital television terrestrial broadcasting system. It appears in the Electronics compliance cluster with a testing methods focus and has an implementation date of Aug 1, 2007.
Applicability depends on product scope, certification route, competent authority notices and transition rules. Requst for the translation or verify source before using this record in a compliance decision.
Compliance overview
Scope and applicability
GB 20600-2006 specifies the framing structure, channel coding and modulation for digital television terrestrial broadcasting systems operating within UHF and VHF bands in an 8 MHz channel bandwidth. This standard applies to terrestrial transmission of digital multiplex television and high-definition television (HDTV) services, supporting both fixed and mobile reception modes. It is mandatory for all manufacturers of digital TV terrestrial broadcasting equipment intended for the Chinese market. The standard covers both multi-frequency network (MFN) and single-frequency network (SFN) configurations, referencing standards such as GB/T 17975.1 for input data interfaces and SJ/T 10351 for RF output interfaces.
Technical requirements
The standard defines a comprehensive transmission system architecture encompassing scrambling, forward error correction (FEC), symbol constellation mapping, interleaving, and frame structure design. The FEC subsystem employs a concatenated BCH and LDPC coding scheme with three code rates (0.4, 0.6, and 0.8), all using a block length of 7488 bits. The system supports multiple constellation mapping modes including 64QAM, 32QAM, 16QAM, 4QAM, and 4QAM-NR, with power normalization applied across all mapping schemes. The standard introduces a unique four-layer frame structure consisting of signal frames, super frames (125 ms), minute frames, and calendar day frames, synchronized with natural time and GPS. Each signal frame comprises a PN sequence frame header and a frame body containing 3780 symbols (36 system information symbols plus 3744 data symbols). Three frame header modes are defined with PN sequence lengths of 420, 595, and 945 symbols respectively. The frame header PN sequences serve dual purposes: system synchronization and channel estimation/equalization. The standard specifies time-domain symbol interleaving with two convolutional interleaving modes, and frequency-domain interleaving for the C=3780 multi-carrier mode. System information is transmitted using spread spectrum technology, mapping 6 information bits to 32-bit vectors using Walsh sequences and pseudo-random sequences. The baseband post-processing employs a Square Root Raised Cosine (SRRC) filter with a roll-off factor of 0.05. The standard supports net payload data rates ranging from 4.813 Mbit/s to 32.486 Mbit/s, depending on the combination of frame length, FEC code rate, and modulation scheme. Both C=1 (single-carrier) and C=3780 (multi-carrier) frame body processing modes are supported, with optional dual pilot insertion in the single-carrier mode.
Testing methods
The standard defines spectrum mask templates for out-of-band emission control, including specific templates for scenarios where digital TV transmitters share sites with analog TV transmitters (PAL system) on adjacent channels, as well as stricter templates for cases where adjacent channels serve other services. The baseband signal spectrum characteristics are specified after pulse shaping filtering. Testing involves verifying compliance with the defined spectral mask turning points at specified relative frequencies, measured in 4 kHz bandwidth with 0 dB corresponding to total output power. The standard also requires verification of frame structure integrity, FEC encoding/decoding performance, constellation mapping accuracy, and interleaving/de-interleaving correctness through the defined PN sequence generation, LDPC code generation matrices, and frequency-domain interleaving patterns specified in the normative appendices.
FAQs
What products are regulated under GB 20600-2006?
GB 20600-2006 applies to all digital television terrestrial broadcasting transmission equipment, including transmitters, modulators, and related systems operating in UHF and VHF bands with 8 MHz channel bandwidth. It covers both fixed and mobile reception devices for standard definition and high-definition digital TV services in China.
How does GB 20600-2006 differ from the DVB-T standard?
GB 20600-2006 (DTMB) differs from DVB-T in several key aspects: it uses a unique PN sequence-based frame header for synchronization instead of cyclic prefixes, employs BCH+LDPC concatenated coding instead of RS+convolutional coding, supports both single-carrier (C=1) and multi-carrier (C=3780) modes, and uses a time-domain synchronous OFDM approach. The standard references EN 300 744 (DVB-T) as a normative reference but implements fundamentally different technical approaches.
What are the three frame header modes in GB 20600-2006?
The standard defines three frame header modes: Mode 1 uses a PN420 sequence (420 symbols, 55.6 μs) based on an 8th-order m-sequence with 225 frames per super frame; Mode 2 uses a PN595 sequence (595 symbols, 78.7 μs) based on a 10th-order m-sequence with 216 frames per super frame; Mode 3 uses a PN945 sequence (945 symbols, 125 μs) based on a 9th-order m-sequence with 200 frames per super frame. In Modes 1 and 3, the frame header average power is twice the frame body power, while in Mode 2 they are equal.
The summary above provides a high-level overview of GB 20600-2006. To ensure complete compliance for your digital TV terrestrial broadcasting products entering the Chinese market, a precise and professional translation of the full technical specifications is essential. Purchase our high-quality English translation of GB 20600-2006 today to access all detailed parameters, LDPC code generation matrices, PN sequence definitions, frequency-domain interleaving patterns, spectrum mask tables, and complete testing procedures.
Applicability hints
- Type
- Method
- CCS
- M63
- ICS
- 33.160
- Competent department
- National Radio and Television Administration
- Technical committee
- National Technical Committee on Radio, Television and Online Audiovisual of Standardization Administration of China