72 results about "Digital television terrestrial broadcasting" patented technology

The invention relates to a method and system for tiered digital broadcasting. A plurality of different bit streams representing digital data targeted for different services is received from a data source. Each bit-stream of the plurality of different bit-streams is modulated on a plurality of OFDM sub-carriers. Sub-carriers of different bit streams have different spectral efficiency. The parallel OFDM sub-carriers of each bit-stream are frequency interleaved with the parallel OFDM sub-carriers of the other bit streams of the plurality of different bit streams such that the parallel OFDM sub-carriers of each bit are spread over an entire available frequency spectrum. The interleaved sub-carriers are transformed into time domain for providing a frequency interleaved OFDM signal. The OFDM signal is then upconverted to the frequency of a broadcasting channel and transmitted. The invention enables a broadcasting station to transmit multiple bit streams with different spectral efficiency using one RF channel.

The present invention discloses a method for modulating digital television ground broadcasting transmitter based on insertion training sequence and LDPC code, wherein the method comprises the following steps: 1) forming an FFT coded data block with the input bit flow through LDPC coding; 2) switching the FFT coded data block to a time domain discrete coded data sample block through IFFT; 3) forming a complex training sequence discrete sample block with a mode that a training sequence is used as a real part sequence and an operational indicator sequence is used as an imaginary part sequence; 4) continuously repeating the complex training sequence for four times to form a time domain insertion training sequence discrete sample block; 5) directly overlapping the time domain discrete coded data sample block with the time domain insertion training sequence discrete sample block for forming a time domain insertion training sequence coded data block; 6) inserting a circulating prefix into the time domain insertion training sequence coded data block for forming a signal frame; 7) forming a signal frame pulse with a square-root raised cosine roll-off filter; and 8) upconverting the baseband signal to the carrier.

A method of burst signal detecting for orthogonal frequency division multiplexing system and a control method for automatic gain can carry out the burst signal detection of baseband digital signal and can utilize the detecting result of the burst signal to control the digital switch and at the same time to control the work of AGC for regulating the gain of the entire system after the analog or thogonal demodulating and analog to digit converting. The method can be easily realized with high detection accuracy, less calculation, can quickly regulate AGC and to be used for various OFDM system such as the European digital video broadcast digital TV ground broadcast and orthogonal frequency division multiple access of radio local net.

The present invention applies to the digital signal processing field, provides a mapping and interlacing method and system for digital television terrestrially broadcast signals. The method includes: acquiring interlacing mode information and modulating mode information corresponding to the input LDPC coding bit data; interlacing the LDPC coding bit data according to corresponding interlacing mode based on the interlacing mode information; based on the modulating mode information, when the modulation mode is one of 64QAM, 32QAM, 16QAM and 4QAM, directly performing constellation mapping of corresponding modulating mode to bit data after interlacing, and when the modulation mode is 4QAM-NR, firstly performing NR quasi-orthogonal pre-mapping and then performing 4QAM constellation mapping to the bit data after interlacing. The present invention, by firstly interlacing and then mapping the bit data stream together, decreases the bits of basic symbols during interlacing, can decrease the size of memory of the interlacing device, and does not require to increase additional module to realize according to the 4QAM-NR mode, thereby reducing the production cost.

The invention relates to a frequency deviation estimating method of a receiver based on a DTTB standard, belonging to the technical field of digital television transmission. The frequency deviation estimating method comprises the following steps of: roughly estimating frequency deviation; carrying out rough frequency deviation compensation on received data according to a rough frequency deviationestimating result; accurately estimating residual frequency deviation; and compensating finally remained residual frequency deviation of the received data according to an accurate frequency deviationestimating result. The invention ensures that the DTTB system can be used for correctly receiving and transmitting signals in large frequency deviation and high-speed movement by using the characteristics of PN (Pseudorandom Noise) sequence circulation of a frame header mode 1 and a frame head mode 3 in a DTTB system.

The related constellation mapping and interlacing method in DTV ground broadcast system is characteristics in that it supports 64QAM, 32QAM, 16QAM, 4QAM and 4QAM-NR five constellation mapping and relative interlacing implementation method. It takes group mapping according to digital signal bit flow to form nQAM (n for constellation point number) for modulation and convolution; to 4QAM-NR, first interlacing then constellation mapping. This invention improves system error correction capacity, adaptability and efficiency.

The invention provides a television receiving system in double modes of digital television terrestrial multimedia broadcasting and the internet. The television receiving system comprises a network detection module, a DTMB channel module, an internet channel module, a media pack caching module and an audio-video decoder, wherein the network detection module is used for detecting the network state of a DTMB network and the network state of the internet; the DTMB channel module is used for receiving and processing television program data of the DTMB network and caching the television program data to the media pack caching module to form first cache data; the internet channel module is used for receiving and processing television program data of the internet and caching the television program data to the media pack caching module to form second cache data; the media pack caching module is used for achieving switching between a DTMB channel and an internet channel according to the network states and a preset switching strategy and sending the first cache data or the second cache data into the audio-video decoder; the audio-video decoder is used for decoding and broadcasting the first cache data or the second cache data. Therefore, the television receiving system can optimize receiving efficiency, receiving cost, the receiving range and television viewing effects of television contents.

The invention discloses a space frequency modulation method for digital TV terrestrial broadcasting transmitter based on embedding training sequence and LDPC coding comprising: 1) coding input bit stream by LDPC and forming coding data block on frequency domain; 2) then demodulating by space-frequency coder and regulating time for synchronization; 3) converting data block after space-frequency modulation to time domain discrete data sample value block via IFFT; 4) training sequence serving as real part, service index sequence serving as imaginary part sequence, constituting discrete sample value block of plural training sequence; 5) repeating continuously the plural training sequence four times to form discrete sample value block of time domain embedded training sequence; 6) superposing the space-frequency modulated time domain discrete data sample value block and time domain embedding training sequence discrete sample value block to form space-frequency modulated time domain embedded training sequence data block; 7) inserting cyclic prefix as protective interval and forming signal frame; 8) pulse shaping to signal frame using square root raised consine roll-off filter; 9) up-converting base band to carrier.

The invention discloses an encoder device and an encoding method of an LDPC code. With the invention, a generator matrix of different code rates is segmented, and the generator matrix after segmentation is validly stored in a memory; when in encoding, the information to be encoded is cached by a plurality of small memories, output bit by bit and multiplied with the generator matrix stored beforehand; then, a summation of the operation results of each bit is summed. When the multiplication of all the information bits and all generator matrix blocks is finished, a parity bit is obtained and output in parallel into an output unit to finish the calculation. The encoder device and the encoding method provided by the invention can encode the LDPC code of single code rate and a plurality of code rates, thus particularly being suitable for the encoder design of the LDPC code of digital ground broadcast standard.

The invention relates to a carrier high-speed wireless wideband image transmission system, belonging to the multimedia information transmission technique. Wherein, said device comprises a carrier image emitter and a ground fixed image receiver; the carrier image emitter comprises an image camera and a wireless image emitter, which can be carried by aircraft to camera the on-site image and send signal, via the wireless transmission channel, based on superior digit television ground broadcast technique; the ground fixed wireless image receiver is used to receive and recover the signal sent from the carrier image emitter, then display image signal directly or transmit the recovered image signal to needed position by some relay. The invention can be used in special conditions as spaceflight engineering, etc, or the conditions as city emergency mechanism.

The invention discloses a modulation method for digital TV terrestrial broadcasting transmitter based on time domain training sequence and LDPC coding comprising: 1) coding input bit stream by LDPC and forming FFT coding data block on frequency domain; 2) converting FFT coding data block to time domain discrete coding data sample value block via IFFT; 3) inserting cyclic prefix as protective interval to time domain discrete coding data sample block and forming time domain cyclic prefix discrete coding data sample block; 4) continuous four time domain cyclic prefix discrete coding data sample value blocks constituting a frame body; 5) training sequence serving as real part of plural training sequence, service index sequence serving as imaginary part sequence to constitute discrete sample value block of plural training sequence; 6) inserting the discrete sample value block (frame head) of plural training sequence in signal frame for forming frame body;7) pulse shaping to signal frame using square root raised consine roll-off filter; 8) up-converting base band to carrier.

An embodiment of the invention discloses a signal receiving test system based on digital television terrestrial broadcasting (DTTB). The signal receiving test system comprises: a signal demodulation module, a transmission mode, a signal analysis processing module and a control module, wherein the signal demodulation module is used to carry out analog / digital conversion to an analog signal received by a receiving antenna and acquire a digital data; the transmission mode is used to transmit the digital signal acquired by the signal demodulation module; the signal analysis processing module is used to analyze and process the digital signal transmitted by the transmission mode, acquire analyzed and processed data and generate a control signal; the control module is used to receive the control signal generated by the signal analysis processing module and sends the control signal to the signal demodulation module so that the signal demodulation module carries out corresponding operation processing according to the control signal. According to the embodiment of the invention, a system C / N threshold and signal emission power can be reduced; current interferences to a television program can be reduced; various kinds of interferences / distortions can be resisted. The system can support fixed, portable, walking, hand-held or mobile receptions.

Before carrying out equalization processing for data stream, the receiving end of the transmission system carries out recognition for transmission mode. The method includes steps: (1) when received data stream reaches system information bit in data frame, the input data starting multiplication to random sequence data in n bits one by one; mode for creating random sequence data in n bits is identical to mode for creating random sequence in system information generation procedure to carry out randomization process for Walsh sequence blocks; (2) after n pieces of symbol are transmitted, Walsh transform is carried out for multiplied result of n bits corresponding to these symbols; (3) fetching one maximal absolute value from n pieces of outputs after Walsh transform; based on definition of mode word in system information in time of transmission, finding out corresponding system information; then, finding out transmission mode of data frame matched to the system information.

The present invention discloses a carrier wave synchronization method and the equipment for a digital television ground broadcast transmission system receiver, which belongs to the digital information processing field. The present invention is characterized in that: first of all, after the frame synchronization, the receiving terminal locally creates a PN serial which is accordant with the receiving frame head, the frequency can be estimated according to the relative results of the fore and after sub serial of the flame head, and the frequency offset signal can be compensated by passing through the loop circuit filtering. The carrier wave synchronization proposal of the present invention is suitable for the flame structures of two modes, the single carrier wave and the multi carrier wave, and at the same time the proposal has the advantages that the synchronizing speed is quick, the anti-noise performance is good, and the present invention suitable for hardware realization.

The invention discloses a method for estimating time delay of ground broadcast signals of a digital television, which belongs to the field of digital television broadcasting and wireless navigation positioning. The method comprises the following steps of: by using a transmitting time marker extracted from transmission code steams which are output from a digital television receiver through demodulation coding, reforming the transmission code streams into television signal frames which have same standard and same time sequence with transmitted signals, and then performing coding and modulation the same as those of a sending terminal in turn frame by frame; reforming a transmitted signal sample of a transmitting station which is nearest to a mobile receiving terminal; and performing cross-correlation operation on the sample and a stored received signal sample so as to accurately estimating the time delay for the broadcast signals transmitted by all single-frequency network transmitting station to reach a mobile terminal through different transmission paths. The method has high time delay estimation accuracy, is simple to implement, and has a low cost and a wide application range.

The embodiment of the invention provides a fine symbol synchronization method for the second generation of digital television terrestrial broadcasting system and a device for the second generation of digital television terrestrial broadcasting system. By the fine symbol synchronization method, a path having a minimum mean square deviation is found out from a plurality of paths to act as a first path, and the formula of the mean square deviation of the first path can be calculated by a simplified mean square deviation formula. Therefore, the fine symbol synchronization method is short in synchronization time, and the first path can be found out correctly, so that a starting position of a Fast Fourier conversion window is locked at the correct starting position of the symbol signal of the first path.

The invention discloses a novel 3780 points DFT processor, which relates to a digital television terrestrial broadcasting system. The processor has one of the following two structures, of which the first structure comprises 140 27 points DFT processors, a complex multiplier, a subscript mapping processor and 27 140 points DFT processors in turn; the second structure comprises the 27 140 points DFT processors, the complex multiplier, the subscript mapping processor and the 140 27 points DFT processors. As for input information including channel impulse response (CIR) vector, the 3780 points DFT processor with the first structure also comprises pruning algorithm to remove the redundant operation in the processor related to zero element in CIR vector. Compared with the prior art, the 3780 points DFT processor provided by the invention effectively reduces the multiplication operation quantity and system power dissipation. Moreover, the invention further reduces the multiplication and addition operation quantity of the processor by pruning algorithm according to the natural characteristics of the CIR vector.

The invention discloses a method for receiving and the transporting signals of digital mobile radio and television which includes china digital television terrestrial broadcast (DMB-TH) and china mobile digital multimedia broadcast used on a handheld device, and a DMB-TH terminal or a CMMB terminal which adopt the method. The method comprises the steps of receiving and transporting, wherein the receiving step is characterized in that DMB-TH or CMMB signals are not only received, but also transported to a MPEG-2TS transport stream including a video steam, a video stream, or other data objects, or a data stream including a video steam, a video stream, or other data objects, the transporting step is characterized in that the feedback MPEG-2TS transport stream including the video stream, the video stream, or other objects, or the data stream including the video stream, the video stream, or other objects, are converted into a format suitable for being transported to an external device and transported to the external device. The DMB-TH terminal or the CMMB terminal comprises an independent power supply, a receiving sub-module, and a communication sub-module, wherein, the communication is a 204 GHz Bluetooth sub-module, so that the adoption of the Bluetooth sub-module enables various information data to be converted by the Bluetooth standard and sent through a wireless device.

The invention discloses a method for detecting and correcting residual frequency offset of the national standard of digital terrestrial broadcasting, which comprises the steps: 1, decoding of system information: recovering the system information of 6 information bits; 2, stability determination: comparing the system information of 6 information bits solved by multi-frame data, determining that the system information is stable if the system information of the continuous multi-frame 6 information bits is totally same; determining that the system information is not stable if the stable system information of the continuous multi-frame is not searched in a certain frame number; and returning to the first step to receive the next data frame if the stable result is not determined; 3, constellation point determination: ending the detection and correction process of the residual frequency offset for a system in absence of the residual frequency offset; and performing the correction of the residual frequency offset for a system in presence of the residual frequency offset. The algorithm has the advantages of small complexity, less logic quantity, simple circuit implementation and less resources.

The invention discloses a large frequency hemiopia estimation method, which is carried out according to circular correlation property of receiving data without using auxiliary data, of a digital television terrestrial broadcasting transmission system receiver and a device thereof, belonging to the processing field of digital information. The invention adopts a digital intermediate signal which is subjected to A / D sampling to be multiplied by a local carrier signal so as to carry out digital down conversion and then forms filtering by a square root raising cosine (SRRC) filter. A complex signal output by the SRRC filter is delayed for Tau sampling points and subjected to conjugation-obtaining, and the delayed and conjugated complex signal is subjected to re-multiplication with the original signal before being delayed. The result of re-multiplication is divided into p branches for summarizing, the results of the p branches are subjected to FFT of p point, and then the estimation value of the frequency offset is obtained. The invention is applicable to the frame structures of two modes: single carrier and multi-carrier, can carry out blind estimation on the frequency offset under the state without any auxiliary information, and has the advantages of large scale of frequency offset estimation, good noise immunity, being suitable for hardware realization and the like.

The invention discloses a synchronized method of low-density parity-check (LDPC) data blocks in 32quadrature amplitude modulation (32QAM) and 4quadrature amplitude modulation-nordstrom robinson (4QAM-NR) of digital television terrestrial broadcasting system (DTMB). The method comprises the following steps: initializing synchronization positions of LDPC data blocks and setting beginning positions of the LDPC data blocks of a first data frame in a frame header of the data frame; receiving new frame data; detecting whether the received frame data is all-zero codes; continuously receiving next frame data if the frame data is all-zero codes; conducting a subsequent determine if the frame data is not all-zero codes; splitting the data frame to a plurality of LDPC data blocks according to the synchronization positions of LDPC data blocks; performing a LDPC decoding operation to the LDPC data blocks; performing a bose-chaudhori-hocquenghen (BCH) data block check on decoded data of the LDPC data blocks; if all the BCH data block checks are failure, which means there are synchronization errors in the LDPC data blocks, switching the synchronization positions of the LDPC data blocks and receiving next data frame; otherwise ending synchronization determination of the LDPC data blocks if synchronization of the LDPC data blocks is correct. In the invention, misjudgments of synchronization positions of the LDPC data blocks caused by bad signals can be reduced.

The invention relates to a pseudo random code sequence phase capturing method used for simultaneous receiving of digital television terrestrial broadcasting signals. The method comprises the following steps: acquiring adjacent signal frames in received signals, extracting frame header PN code sequences of the signal frames, carrying out slide-correlating operation on the frame header PN code sequences and local PN code sequences to obtain a correlation result, and detecting a correlated peak position corresponding to each signal frame; based on the correlated peak positions, carrying out first-difference operation on the correlated peak positions of the adjacent signal frames in the received signals to obtain correlated peak intervals and peak deviations corresponding to the signal frames; carrying out second-difference operation on the adjacent peak deviations to obtain a second-difference differential value; and searching a second-difference differential value search sequence for a result corresponding to the second-difference differential value, and determining sequence numbers corresponding to the signal frames. The pseudo random code sequence phase capturing method eliminatesthe influence of timing errors on the adjacent signal frames and avoids the interference of timing errors on the pseudo random code sequence phase capturing by using the second-difference method.

The invention relates to a method for estimating channel of digital TV terrestrial broadcasting and a device thereof, which pertains to the technical filed of digital information transmission and is applicable to national standard digital TV terrestrial broadcasting (GB 20600-2006) systems, digital communication systems, telemetry and telecontrol systems and other relevant systems and technical fields. Under the frame head modes of PN420 and PN945 of digital TV terrestrial broadcasting, the multipath channel impulse response which falls into the prefix length range of the frame head PN sequence can be estimated by the following processing of sampling sequence of symbol rate after synchronization: (a) synchronization and pre-processing; (b) cyclic correlation; (c) channel impulse molding. The method and the device of the invention utilize diversity gain brought by the PN sequence correlation, have good anti-noise performance, can effectively reduce interference resulting from non-ideal autocorrelation of the PN sequence , accurately and fast estimate the multipath channel impulse response which falls into the prefix length range of the frame head PN sequence and have the advantages of high estimation accuracy, small calculation amount and low implementation complexity compared with other methods.

A multi-channel single frequency network front-end center transmitting station of digital television terrestrial broadcasting includes a program signal input part, a source processing part, a channel processing part, a transmitting train-synthesis-transmitting antenna feed part, and a data-software management control part; adopts mature digital source coding and processing technology to perform channel coding and modulation processing meeting China national standard GB20600-2006 to the transmitted channels, and form a multi-channel DTTB transmission network center transmitting station according to the needs of system operations; and has main characteristic that it adopts adjacent channels or alternate channels same station transmitting, same station transmitting of multi-channel same power or different transmitting powers. The transmitting station can constitute a network separately, more importantly, provide front-end supports for the formation of digital television terrestrial broadcasting multi-channel single frequency network.

The invention relates to the technical field of digital information transmission. The invention provides an embedded multi-service transmitting method based on China Digital Terrestrial Multimedia Broadcast (DTMB) standard and a device for realizing the method. On the premise of not changing the receiving end in the traditional China DTMB standard at all, the method designs a new transmitting end structure and transmits multiple services in an embedded mode. The device comprises a randomizing module, an embedded multi-service coding module, an embedded multi-service fixed expansion mapping module, an embedded multi-service data format matching module, an embedded multi-service randomizing module, a multiplexing module, a China DTMB standard system randomizing rear transmitting end module and a control module. The invention expands the existing system of the China DTMB standard to transmit multiple services in an embedded mode, and adds the functions of power saving and the like, thereby widening the application range of China DTMB standard. The invention is especially suitable for single-transmitter operation and wide-range single-frequency network.

The invention brings forward a testing method for network coverage of a ground broadcast network of a digital television. The testing method comprises the following steps that: a testing receiving plate of a ground broadcast network of a digital television receives a ground broadcast network signal of the digital television and sends receiving analytical data to a data processing module according to the round broadcast network signal of the digital television; according to the receiving analytical data, the data processing module determines field intensity and receiving performance corresponding to a specific position by combining a field intensity signal as well as latitude and longitude information; and field intensity of the current time and real-time statistical information of an error code are displayed according to the field intensity and the receiving performance corresponding to the specific position. According to a technical scheme provided in the invention, the variation of different interfaces can be shielded by means of software; testing data, time and geographic information are combined by utilizing a GIS assembly, so that a test process can be displayed vividly and visually; meanwhile, a network coverage test of a ground broadcast network of a digital television can also be effectively realized.

The invention provides a method for detecting the sequence number of a frame header in Chinese digital television terrestrial broadcasting. Frame coarse synchronization is performed by using the structure that the frame header of a signal frame in different superframes of a signal repeatedly appears, and then the specific sequence number of the frame header is determined by using the structure that the frame header of the signal frame in one superframe is symmetrical back and forth. The sequence number of the frame header of a specific signal frame is determined from a television signal in two steps. The method can be used for calculating a pseudo-range in a positioning process which is performed by using a Chinese digital television terrestrial broadcasting system and can be also used for frame synchronization for the signal. Without generating a local performance number (PN) through a receiver, the position and the sequence number of the frame header can be accurately determined by a method of detecting related peak value for two times, so that the complexity of the system is reduced, and the calculation amount of the system is reduced. The auto-correlation of the signal is adopted, so the requirement on the receiving effect of the signal is relatively low. The method is also suitable for positioning in a region with a relatively poor television signal.

The invention discloses a digital television terrestrial broadcasting system and a construction method thereof. The system comprises at least one transmitter; the transmitter comprises a first filtercircuit, a first front-stage amplification unit and a power amplification unit, which are connected in sequence, wherein the transmitter is used for receiving a digital television terrestrial broadcasting network signal from the air, processing the digital television terrestrial broadcasting network signal, and then, transmitting the digital television terrestrial broadcasting network signal; thefirst filter circuit is obtained based on the frequency of the received signal; and furthermore, the power and the number of the transmitter are determined according to the area and the terrain needing to be covered and the signal value of the received signal. According to the digital television terrestrial broadcasting system and the construction method thereof disclosed by the invention, the low-power transmitter is adopted; selection requirements on a transmitting point can be reduced; therefore, the transmitting point can be flexibly arranged; in addition, the filtered and amplified signalis transmitted in a guard interval in a supplementary manner; and thus, a main coverage signal blind area can be repaired.

The invention discloses a carrier tracing loop of digital TV ground broadcast in the digital signal transmission domain, which comprises the following parts: equalizer FIR, DFE, complex multiplier, adder, judger, subtracter, real multiplier, accumulator and loop low-pass filter, wherein the demodulated complex signals is composed of I and Q paths, which is output as complex signal through equalizer FIR; the complex signal is multiplied by total phase difference phi with real baseband signal being fetched out in the adder with DFE output, which obtains the output of equalizer; the judger disposes the signal, which enters into subtracter after DFE; the signal and imaginary part Q' output by equalizer FIR are sent in the real multiplier; the signal is sent in the accumulator to eliminate phase-detector noise, which outputs driving frequency error signal delta f of digital control oscillator.