Tag: DMB-H DMB-T
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DMB-T/H mobile receiving digital TV system features
The combination of orthogonal multi-carrier technology with time domain synchronization and frequency domain signal processing enables the demodulator to lock it quickly under lower C/N conditions; it has strong penetration and strong resistance. Multipath interference and Doppler shift ensure that fast-moving users in the coverage area can receive normally.
(1) Compatibility. At present, there are 33 countries and regions in the world that choose DVB-T technology standard. Both DMB-T technology and DVB-T technology adopt OFDM signal debugging mode, which has basically the same effective signal bandwidth and spectrum characteristics. Therefore, the DMB-T can use the same spectrum protection ratio as DVB-T to PAL, PAL to DVB-T, DVB-T to DVB-T for co-channel interference and adjacent channel interference. Since the minimum received field strength required by DMB-T is lower than that of DVB-T, the frequency planning scheme required by the DVB-T system can be used for the DMB-T system. The same antenna, broadcast transmitter and tuner can be used for DMB-T and DVB-T systems.
(2) High data rate, in the 8MHz TV channel, the maximum payload rate is up to 33Mb/s, which can meet the HDTV broadcasting requirements; overcome the cliff effect of digital TV, so that DMB-T can be used for DTV broadcasting, Can be used for data communication.
(3) Support for cellular single frequency networks, which means that adjacent television stations can broadcast the same content using the same frequency, and can cover a wide range with low transmission power. The single-frequency network is beneficial to frequency planning, increases spectrum utilization, and allows the limited frequency resources to be fully utilized. It can further introduce communication technologies in the broadcast protocol, enabling DMB-T to support cellular single-frequency networks, enabling people to ride cars and Reliable, instant multimedia information services are available on trains.
(4) Introducing the frame structure of time slicing and absolute time synchronization, which is convenient for automatic wake-up function setting, achieves power saving purposes, and supports portable mobile phone reception.
(5) Adopting the time domain synchronization scheme, the data detection and identification is fast and the channel estimation is accurate and fast, and the best reception effect is obtained.
(6) Strong receiving ability under various conditions and environments; using the most advanced error correction technology and signal modulation technology, the receiver can reliably receive signals under various conditions and environments, and has strong anti-interference ability ( 24dB spread spectrum gain), capable of anti-static multipath (simple antenna reception) and dynamic multipath interference (suitable for reception in sports environments) and various home appliance pulse interference; using hierarchical coding technology to make standard definition and HDTV signal transmission compatible .
(7) Construction network costs and operating costs are low. DMB-T technology supports mobile reception making it an ideal wireless solution. Support for bursty data enables it to process short data or messages. Supporting the cellular network enables it to be extended. The DMB-T uses a time domain spread spectrum synchronization sequence with the capability of code division multiple access, which can identify signal frames, base stations, and the like. Therefore, DMB-T can be used to form a cellular broadcast network, and directional transmission can also be realized; DMB-T protocol and absolute time synchronization support timed reception, storage and power saving applications, and important features for handheld devices and portable devices. Ideal for future digital TV broadcast systems to meet future larger capacity needs (interactive multimedia broadcasts, cellular broadcast networks, etc.).
At the same time, terrestrial digital TV, as a kind of coverage different from satellite and cable TV, can give full play to its unique advantages, and will serve the future broadband wireless access market, support the mobile receiving industry, and support the two-way service of wireless two-way transmission. The promotion and industrialization of digital TV terrestrial broadcasting will bring new economic growth points and bring new development opportunities for the broadcasting and television industry.
system integration
DMB-H can support data streams packed from 4.8Mbps to 32.4Mbps in MPEG-2 transport stream format, which can support bit rate.
High-definition digital TV format of around 20Mbps. DMB-H meets the needs of all existing and extended services of mobile TV, achieving improved spectrum utilization, higher quality and more types of broadcast TV service services. For the standard bandwidth of 8MHz in China, the data of the transmission rate is shown in Table 2 below.
Table 2 DMB-T System Payload Table
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