34 results about "Digital terrestrial multimedia broadcasting" patented technology

A Digital Terrestrial Multimedia Broadcasting (DTMB)-based carrier mode detection system includes first and second TPS decoders, first and second carrier calculators and a determinator. The first and second TPS decoders respectively receive NTPS input signals to thereby produce the corresponding NTPS mask signals and to respectively perform an absolute operation on the corresponding NTPS mask signals to accordingly select a maximum result as first and second absolute maximum mask signals for output. The first and second carrier calculators respectively receive NCS input signals and produce first and second absolute summation carrier signals. The determinator is based on the first absolute maximum mask signal, the first absolute summation carrier signal, the second absolute maximum mask signal and the second absolute summation carrier signal to accordingly determine that the carrier mode is of a multi- or single-carrier mode.

The invention discloses a transmission method of time domain synchronous-orthogonal frequency division multiplexing (TDS-OFDM) based on a theory of compressive sensing and relates to the field of wireless communication. The method comprises the following steps: on the basis of self-correlation properties of a received training sequence and a local training sequence, obtaining parts of prior information of multi-path channels, and confirming a position of a non-interference area in the received training sequence according to the channel length of the multi-path channels included in parts of the prior information; according to parts of the prior information and on the basis of the theory of compressive sensing, calculating time delay of each path of the multi-path channels; and according to signals in the non-interference area and on the basis of a maximum likelihood algorithm, calculating coefficient of each path of the multi-path channels. According to the transmission method of the TDS-OFDM based on the theory of the compressive sensing, two technical problems that the TDS-OFDM is difficult to support high order modulation of 256 quadrature amplitude modulation (QAM) and the performance deterioration in dynamic channels is obvious are solved, and a strong theoretical and technical support is provided so that digital terrestrial multimedia broadcasting (DTMB) can catch up with and surpass the advanced international levels in key performance indicators of spectral efficiency, high-speed motion and receiving and the like.

The invention discloses a method for capturing the frame header PN of a digital terrestrial television system. When receiving a signal frame to recover data, a digital terrestrial multimedia broadcasting (DTMB) system simplifies relevant calculation of time domain by utilizing the group calculation of FFT and IFFT and judges whether a frame header PN sequence is successfully captured or not by comparing a relevant peak and a capturing threshold. By applying the method of the invention, a PN mode selected and used by the frame header of an identification signal frame can be quickly captured so as to provide necessary conditions for the follow-up process of a receiver; the speed of relevant calculation is improved and computational complexity is reduced; meanwhile, other treatment methods and logic circuits are not required to be added when the frame header rotates in phases of PN420 and PN945 modes, thus circuit structure is simplified so as to improve the speed for capturing the frame header PN in a digital terrestrial television broadcasting transmission system.

The invention relates to a solution to parallel encoding of the QC-LDPC (quasi-cyclic low-density parity-check) codes with three different code rates in a DTMB (Digital Terrestrial Multimedia Broadcasting) system. The solution is characterized in that a parallel QC-LDPC code encoder of the system mainly comprises four parts including a register, lookup tables, a bc-bit two-input exclusive-or gate and a b-bit two-input exclusive-or gate. The parallel QC-LDPC code encoder provided by the invention is compatible with multiple code rates, can fully use the functions of the lookup tables in the FPGA (field programmable gate array) logic resources to reduce the resource demand effectively under the condition of keeping the encoding speed unchanged, and has the advantages of being easy to control, consuming few resources and power, being low in cost, etc.