CN1177475C - Data Interleaving Method in Digital TV Transmission - Google Patents

Abstract

The present invention relates to a method for interlacing data in digital television transmission, which is characterized in that each synchronous signal comprises three-bit interlacing information, and the interlacing information indicates the branch numbers of a parameter convolution interlacing device of an interlacing device and the byte numbers of each memory cell. Inputted streams enter the interlacing device after being randomized and coded by RS (208, 188), and the interlacing device interlaces the data in a convolution interlacing mode synchronously to packet synchronous signals. In a single modulation mode, the data of streams share the same interlacing device. In a mixed modulation mode, mixed streams which correspond to the modulation mode respectively use respective interlacing devices. In the method, different interlacing modes can be selected according to the different requirements of different streams so as to guarantee the flexibility of a system for transmitting various streams.

Description

Data Interleaving Method in Digital TV Transmission

                      

The invention belongs to the field of digital signal transmission, in particular to a data interleaving method in digital television transmission.

Background technique

A typical digital transmission system includes a transmitter and a receiver. Digital modulation technology often encodes digital signals, and then adds necessary auxiliary information, such as: synchronization signals, pilot signals, etc. The coded digital signal forms a baseband signal after channel filtering. The baseband signal is modulated to a corresponding frequency band through an up-converter and then sent. At the receiving end, the tuner converts the high-frequency signal to the baseband to obtain a digital signal through an analog-to-digital converter. After the digital signal is processed, it is restored to the same information as the sending end. In order to deal with the impact noise (Impulse Noise) interference in the channel and cooperate with channel coding, the digital TV broadcasting transmission system needs to perform interleaving processing on the data. Although interleaving is beneficial for encoding, it does not participate in the encoding process. Usually, data interleaving adopts a convolutional interleaving algorithm. Convolutional interleaving disrupts continuous byte groups by effectively dispersing different numbers of bytes in the data structure, so that burst errors are dispersed so that correct data can be recovered with error correction decoding, and deinterleaving performs corresponding reverse processing . Data interleaving involves three important parameters, namely the expected maximum impact noise length L _N , the number of errored bytes L that can be corrected by the RS decoder, and the size of the RS block L _RS . Accordingly, the designed interleaving depth L _M should at least reach L _M =L _N ×L _RS /L. If the interleaving depth is too small, the effect of avoiding impact noise is poor. However, the interleaving depth cannot be designed too large, otherwise the interleaving at the encoding end and the deinterleaving at the decoding end will cause a large system transmission delay, which will cause problems for broadcasting systems (especially cable broadcasting systems) with two-way interactive communication requirements. on the limit.

Contents of the invention

The purpose of the present invention is to design a corresponding data interleaving method for a digital television transmission system compatible with stream mixing and modulation mode mixing at the same time, so as to effectively avoid impact noise interference in the channel, and simultaneously simplify the structure of the realization circuit.

Digital TV transmission includes a single modulation mode and a mixed modulation mode. The single modulation mode refers to the use of one of multiple QAM modulation methods, and the mixed modulation mode refers to the mixing of multiple QAM modulation methods. The TS stream or packet data stream input during data transmission is randomized and sent to the interleaver through (208, 188) RS coding; the interleaver uses convolutional interleaving for data interleaving; the interleaver is synchronized with the packet synchronization; after interleaving The data is sent to the mapper for mapping, and each group of mapped data symbols is inserted into a synchronization signal; each synchronization signal is composed of 288-bit synchronization information, including 3-bit interleaving information; the 3-bit interleaving information indicates the parameters of the interleaver B and M, where B is the number of branches of the convolutional interleaver, and M is the number of bytes of each storage unit. In the single modulation mode, all TS streams or packet data streams are mixed and use the same interleaver; in the mixed modulation mode, each modulation mode corresponds to an interleaver, and each stream using the same modulation mode uses the same interleaver.

When the 3-bit interleaving information is 000, B=104, M=1; when it is 001, B=52, M=2; when it is 010, B=52, M=1; the interleaving information is reserved for others, It can be used for function expansion in the future.

The present invention can select different interleaving modes according to different requirements of different streams, and the receiver can automatically identify the interleaving modes, thereby ensuring the flexibility of the system to transmit multiple streams.

Description of drawings

Figure 1 is a block diagram of the transmission system;

Figure 2 is a structural diagram of an interleaver.

Detailed ways

As shown in Figure 1, after the input stream is mixed, scrambling, RS coding, interleaving, and mapping are performed. The mapped data is inserted into synchronization information through the multiplexer MUX, then QAM modulated, and finally output after IF amplification. The coordinated work of the whole system is completed by the control unit.

As shown in FIG. 2, the present invention inserts each group of transmission data into a synchronization signal, and each synchronization signal is composed of 288-bit synchronization information, including 3-bit interleaving information. The interleaving information indicates parameters B (B=104) and M (M=1) of the interleaver, where B is the number of branches of the convolutional interleaver, and M is the number of bytes of each storage unit. The input stream is randomized and enters the interleaver after being encoded by (208, 188) RS. The interleaver performs data interleaving in a convolutional interleaving manner. The interleaver is synchronized to the packet synchronization signal. In the single modulation mode, the data of each stream uses the same interleaver; in the mixed modulation mode, the mixed streams corresponding to each modulation mode use their own interleavers, and the outputs of different interleavers are multiplexed according to the modulation mode, and then Sent to the mapper for symbolic mapping.

Claims (2)

1. The data interleaving method in digital television transmission is characterized in that: digital television transmission comprises single modulation mode and mixed modulation mode, and single modulation mode refers to adopting a kind of in multiple QAM modulation modes, and mixed modulation mode refers to multiple The TS stream or packet data stream input during data transmission is randomized and then sent to the interleaver through (208, 188) RS coding; the interleaver uses convolutional interleaving for data interleaving; interleaving The device is synchronized with the packet synchronization; the interleaved data is sent to the mapper for mapping, and each set of mapped data symbols is inserted into a synchronization signal; each synchronization signal is composed of 288-bit synchronization information, including 3-bit interleaving information; the 3 The bit interleaving information indicates the parameters B and M of the interleaver, where B is the number of branches of the convolutional interleaver, and M is the number of bytes of each storage unit; in a single modulation mode, all TS streams or packet data streams pass through The same interleaver is used after mixing; in the mixed modulation mode, each modulation mode corresponds to an interleaver, and each stream using the same modulation mode uses the same interleaver. 2. The data interleaving method according to claim 1, characterized in that: when the 3-bit interleaving information is 000, B=104, M=1; when it is 001, B=52, M=2; it is 010 , B=52, M=1; the interleaving information is reserved for other times, and can be used for function expansion in the future.

Images