Digital videocast modulating method and device

Abstract

This invention discloses one digital television broadcast signal modulation method, which comprises the following steps: multiplying data signals, pre-generated frequency characters and synchronous wave load and zero wave load distributed symmetrically, wherein, the said guidance characters occupies one part wave load with each load wave not adjacent distributed; the time area signals adds protection isolation with zero filled to form one OFDM character by use of more than one OFDM character and one front frequency signal to generate base band send signals.

Description

technical field [0001] The invention relates to the field of digital TV broadcasting, in particular to a modulation method and device for digital TV broadcasting. Background technique [0002] Digital TV broadcasting is a research and application hotspot in the field of broadcasting technology at present, and many countries have launched their own digital TV broadcasting systems one after another. At present, there are various modulation techniques for digital TV broadcasting, among which, the DVB-T standard adopts Orthogonal Frequency Division Multiplexing (OFDM) modulation in terms of transmission, which belongs to the multi-carrier transmission technique. [0003] Referring to FIG. 1 , the modulation structure of the transmitter defined by the DVB-T standard includes an OFDM modulation unit 100 , a guard interval insertion (CP) unit 104 and a framing unit 105 . Wherein, the OFDM modulation unit 100 includes a serial / parallel conversion unit 101 , an inverse fast Fourier ...

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Problems solved by technology

[0004] From the above modulation system, CP needs to be inserted into the signal after OFDM modulation. Since CP and data have certain correlation characteristics, the receiver can complete timing synchronization by relying on CP. However, transmitting CP needs to consume a certain amount of power.

However, fading channels, special values ​​of data signals, etc. will deteriorate the correlation between CP and data, thus greatly reducing the speed and accuracy of timing synchronization

[0005] Moreover, for all digital broadcasting systems based on OFDM modulation, there is a common problem: the peak-to-average power ratio (PAPR) is generally high, which will directly lead to a decrease in the use efficiency of the power amplifier of the transmitter, especially when the number of carriers is small. When it is large, such as 8k mode of DVB-T, the power amplifier efficiency of the transmitter is very low

Unfortunately, the existing DVB-T system does not take this issue into account

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