Handheld products to achieve DVB-H digital TV (with photos) - digital TV, mobile TV, digital TV set-top boxes - Broadcasting industry

Handheld products to achieve DVB-H digital TV (with photos) - digital TV

, mobile TV, digital TV set-top boxes - Broadcasting industry

Present, many buses, taxis, both to install a digital TV, this television technology used is DVB-T (Digital Video Broadcasting - Terrestrial). DVB-T power comparison, it is not suitable for battery-powered mobile devices to use. To this end, the DVB-T based on the introduction of new technologies, form suitable for mobile terminals to receive terrestrial digital TV transmission standard DVB-H (digital video broadcasting - handheld). Compared with DVB-T, DVB-H terminals with lower power consumption, mobile reception, and anti-jamming performance is superior.

DVB-H standard is based on DVB and DVB-T standard on two criteria. A DVB-H system receiver front-end is a DVB-H wrapper and DVB-H modulator, DVB-H package is responsible for the IP data encapsulation into MPEG-2 Systems Transport Stream (TS), DVB-H modulator for the channel coding and modulation; system terminal by the DVB-H DVB-H demodulator and terminal form, DVB-H demodulator for channel demodulation, decoding, DVB-H terminal is responsible for operations related to processing, display.

Key technologies In DVB-H, the data link layer using the time slicing technology is the one bright spot, it is used to reduce average power consumption of handheld devices to facilitate a smooth and seamless business exchange. Multi-protocol encapsulation (MPE) FEC technology to improve signal to noise ratio of mobile use (S / N) threshold and Doppler performance, but also can enhance the anti-pulse interference.

Time Segmentation, by definition, Time Division Multiplexing technology. It solved the problem handheld mobile digital TV receiver in the high power consumption. As a result of burst mode transmission of data, each burst transmission time slice of a business, delivery time in the business of the business single-chip holds all the data bandwidth, and that the next time slice generated by the same business time. For the receiver, the only time specified in the packet can receive data. In this way, hand-held terminal can be selected to receive the specified time business, free time to do energy conservation in business processing, thereby reducing the overall average power consumption. Of course, this period is the front-end transmitter has been working in the same business will be sent between the two time slots of other business data, DVB-H signal is the time slice by the number of such composition. From the receiver's point of view, the operational data received is not a constant rate as the traditional continuous mode, the data arrival interval discrete way, to achieve burst transfer. If the decoding terminal requests a lower data rate, but must be a constant rate, the receiver can first of all the received burst data to the buffer, and then generate the data flow rate unchanged. Burst bandwidth is usually fixed at about 10 times the bandwidth. Twice the bandwidth at a fixed bandwidth of sudden case of power could save 50%, 10 times the bandwidth, so if you can save 90%. In addition to lowering power consumption, the time slicing technology is also beneficial to different networks to achieve a smooth data exchange. In the data transmission idle time, the adjacent cellular mobile terminal can monitor, scanning other frequency signals, test signal strength, this way when the user enters a new network, the mobile terminal to monitor the results based on the idle time in the signal to switch to a different transport stream on different networks to achieve a smooth data exchange.

DVB-H standard in the data link layer for the IP datagram added Reed? Solomon (RS) error correction coding, as MPE forward error correction coding, verification of information in the specified FEC ( FEC) section of the transmission, that is multi-protocol Encapsulation - Forward Error Correction (MPE-FEC). MPE-FEC goal is to improve the mobile channel in S / N, pulse Doppler and resistance to interference.

Proved even in very poor reception environment, the proper use of MPE-FEC can still be accurate reconstruction of the IP data. MPE-FEC data overhead allocation is very flexible, in other transmission parameters unchanged, if the checksum overhead to 25%, the MPE-FEC enables handheld devices to and use of antenna diversity reception when the same S / N. DVB-H IP-based data broadcast, DVB-H physical layer based on the DVB-T supplement. In the DVB-T system, 2K mode 8K mode better than the mobile reception performance, but the 2K mode symbol period and guard interval is very short, so 2K mode only for small single frequency networks. DVB-H 4K mode increases with a longer period and symbol guard interval, to the construction of medium-sized single-frequency network, better network optimization, spectrum efficiency. This optimization is not as efficient 8K mode, but the 4K mode 8K mode symbol period than the short, more frequent channel estimation, provides a better mobile performance than the 8K. Therefore, 4K mode and performs between 2K and 8K modes, for coverage, spectral efficiency and mobile reception performance of the trade-off to provide an additional option. 2K and 4K mode in-depth symbol interleaver, can further improve the environment and the impact of noise in the mobile environment, the system reliability. Through the coordination of mobile reception performance and the scale of a single frequency network to further improve network design flexibility.

Receiver design

Now many companies dedicated to portable terminals DVB-H receiver module design. Here, I described the reception module is Freescale's MC44CD02 direct conversion tuner and DiBcom's DiB7000-H channel decoder. Use of this tuner, users can in a variety of harsh conditions are DVB-H services.

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