Digital Terrestrial Multimedia Broadcast

Overview

Previously known as DMB-T/H (Digital Multimedia Broadcast-Terrestrial/Handheld), the DTMB is a merger of the standards ADTB-T (developed by the Shanghai Jiao Tong University), DMB-T (developed by Tsinghua University), and TiMi (Terrestrial Interactive Multiservice Infrastructure); this last one is the standard proposed by the Academy of Broadcasting Science in 2002.

At first, neither Shanghai Jiao Tong University nor Tsinghua had enough political strength to make their own technology become the unique standard, so the final decision was to opt for a double standard, merged with the TIMI 3 standard, responding to a need for backward compatibility.

The DTMB was created in 2004 and finally became an official DTT standard in 2006.

DTMB in China

2005 trial
01/01/2006 formal adoption and official launch as a DTT standard
08/08/2008 analog switchoff started
01/01/2015 analog switchoff completed

DTMB channel available in China

National:
- CCTV-1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, CGTN English
Provinces:

Main channel of province TV in each province

High Definition Channel:
- Varies
City or Local channel:
- Varies

DTMB in Hong Kong

01/01/2006 formal adoption and official launch as a DTT standard
31/12/2007 analogue switchoff started
01/01/2015 analogue switchoff completed

DTMB in Macau

01/01/2006 formal adoption and official launch as a DTT standard
15/07/2008 analogue switchoff started
01/01/2015 analogue switchoff completed

DTMB elsewhere

DTMB started in Laos in 2007.
Cambodia adopted the DTMB standard in 2012.
The Comoros chose DTMB in 2013.
Cuba adopted DTMB in 2013.
In 2017, Pakistan and ZTE signed a contract to deploy DTMB broadcasts in the country by 2020.
East Timor adopted DTMB, and work to implement it started in 2019.

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Versus CMMB

See China Multimedia Mobile Broadcasting (CMMB).

Countries and territories using DTMB

As of August 2025, the following countries use the DTMB broadcast standard: neighbouring countries may also pick up DTMB signals due to signal overspill.

Description

Besides the basic functions of traditional television service, the DTMB allows additional services using the new television broadcasting system. DTMB system is compatible with fixed reception (indoor and outdoor) and mobile digital terrestrial television.

Mobile reception: is compatible with digital broadcasting TV in standard definition (SD), digital audio broadcasting, multimedia broadcasting, and data broadcasting service.
Fixed reception: in addition to the previous services, also supports high definition digital broadcasting (HDTV).

Modulation

The DTMB standard uses many advanced technologies to improve their performance. For example, a pseudo-random noise code (PN) as a guard interval that allows faster synchronization system and a more accurate channel estimation, Low-Density Parity Check (LDPC) for error correction, modulation Time Domain Synchronization - Orthogonal Frequency Division Multiplexing (TDS-OFDM), which allows the combination of broadcasting in SD, HD, and multimedia services, etc.

This system gives flexibility to the services offered to support the combination of single-frequency networks (SFN) and multi-frequency networks (MFN). The different modes and parameters can be chosen, depending on the type of service and network's environment.

The sequence of pseudo-random pattern is defined in time domain, and the information of the Discrete Fourier transform (DFT) is defined in the frequency domain. The two frames are multiplexed in the time domain, resulting in Time domain synchronization (TDS).

Functional scheme

This transmission system makes the conversion of the input signal to the output data of terrestrial TV signal.

The data passes through the encoder, the error protection process FEC (Forward Error Correction), through the constellation mapping process, and then the interleaving processes the information to create the data blocks. The data block and the TPS information are multiplexed, and pass through the data processor to form the body structure. It combines information from the body and the head to form the frame and this is passed through the SRRC (Square Root Raised Cosine) filter to become a signal within an 8 MHz channel bandwidth. Finally, the signal is modulated to put it in the corresponding frequency band.

Features

Bit-rate: from 4.813 Mbit/s to 32.486 Mbit/s
Combination of SD, HD, and multimedia services
Flexibility of services
Time and frequency domain of data-processing
Broadcasting of between 6 and 15 SD channels and 1 or 2 HD channels
Same quality of reception as wire broadcast