288results about How to "Clock jitter is small" patented technology

The invention provides a multichannel high-speed parallel alternate ADC (Analog to Digital Converter) sampling circuit, which comprises an analog differential signal input module, a clock generating and phase-splitting module, a parallel ADC module and a data transmission module, wherein each data output end of the analog differential signal input module is connected with each corresponding data input end in the parallel ADC module; each clock output end of the clock generating and phase-splitting module is connected with each corresponding clock input end in the parallel ADC module, and each data output end of the parallel ADC module is connected with the data transmission module; and a phase splitting unit consists of passive power divider, wherein each passive power divider is used for equally dividing an input clock phase and then outputting the input clock phase. The multichannel high-speed parallel alternate ADC sampling circuit finishes the phase splitting on a clock signal by using the passive power dividers, is little interfered because no power supply is needed for supplying power, and has high phase-splitting precision on the clock signal and small clock jitter.

The invention discloses a method for transmitting an anti-noise wireless multi-media broadcast signal in a single frequency network. In the method, the wireless multi-media broadcast signal is transmitted to an air wireless channel by a wireless multi-media broadcast transmitter in the single frequency network through the following steps: the multimedia data streams are processed by a central data manager; a network data manager carries out LDPC (Low Density Parity Check) coding, code element modulating and constellation rotation on bit streams; space-frequency coding modulation is carried out; discrete data sample value blocks in the time domain and embedded discrete sample value blocks of training sequences in the time domain are superposed to form frames; pulse shaping is carried out; up-conversion is carried out on a baseband signal to a carrier wave to form a radio-frequency signal to be transmitted to the air wireless channel; and a receiver terminal receives and processes the signal transmitted by the wireless multi-media broadcast transmitter in the single frequency network. The method has the advantages of short synchronous receipt time, environmental background noise resistance, large-range controllable multiple services in the single frequency network, etc.

The invention discloses a clock and data recovery circuit and a clock and data recovery method. The clock and data recovery circuit comprises a clock generation module, a clock selection module, a phase discriminator and a digital correlation processing module, wherein the clock generation module is used for receiving input clock signals, generating multi-channel clock signals identical in frequency and different in phase and sending the multi-channel clock signals to the clock selection module; the clock selection module is used for selecting continuous multi-channel clock signals from the multi-channel clock signals identical in frequency and different in phase to the phase discriminator and selecting one-channel clock signal serving as a data lock to the digital correlation processing module; the phase discriminator is used for receiving input data, oversampling the input data according to multi-channel oversampling clocks and sending the oversampled data to the digital correlation processing module; the digital correlation processing module is used for processing the oversampled data, recovering the data and feeding back one clock selection signal to the clock selection module; according to the feedback clock selection signal, the clock selection module selects and outputs the clock signals as same as the recovered data in phase. The clock and data recovery circuit has he advantages of simple structure, short locking time, small recovered clock jitter and the like.

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.

The invention discloses a multiuser OFDM modulation method based on embedded training sequence and LDPC coding, which includes the following steps: 1) each user inserting zero even in its own training sequence to form discrete FFT training sequence block; 2) each user performing LDPC coding to its own input data bit stream to further form an FFT coding data block; 3) directly superimposing the discrete FFT training sequence block and the FFT coding data block to form an FFT embedded training sequence coding data block; 4) adopting IFFT to switch the FFT embedded training sequence coding data block into a time-domain discrete sample block; 5) taking circulating prefix as guard interval to insert into the time-domain discrete sample block to from a signal frame; 6) using a Raised Cosine Roll-off Filter to perform pulse shaping to the signal frame; 7) upconverting the baseband signal to carrier. The method has advantages of short synchronization time, channel dwindle resistance and multiuser disturbance resistance and the like.

The invention discloses a multimedia broadcast mobile signal robust framing modulation method, and belongs to a time domain and frequency domain mixed framing modulation scheme. The multimedia broadcast mobile signal robust framing modulation method has the advantages of low peak-to-average power ratio, short synchronous time, robustness, controllable multi-service and the like.

The invention discloses an anti-fading digital mobile broadcast signal transmission method which is a time domain frequency domain mixed transmission scheme. The anti-fading digital mobile broadcast signal transmission method of the present invention has the advantages of low peak-to-average power ratio, short synchronization time, fading resistance, control of multiple services and the like.

The invention discloses a transmission method of anti-noise digital wireless broadcasting signals. The transmission method is a framing modulation scheme with time domains and frequency domains being mixed. By means of the cascading interleaving coded modulation, the training sequence optimization design, the signal generating models and a signal selection method of the transmission method of the anti-noise digital wireless broadcasting signals, original signals of OFDM signals can be easily processed at a receiver end through processing and restoring, and the transmission method has the advantages of being low in PAPR, short in synchronous time, channel fading resistant, capable of controlling multiple services, and the like.

The invention discloses an anti-noise digital broadcast wireless signal transmitting method, and relates to a time domain/frequency domain mixed scheme. The anti-noise digital broadcast wireless signal transmitting method has the advantages of low peak-to-average power ratio, short synchronization time, resistance to channel noise, controllable multiple services and the like.

A digital-analog conversion method which can decrease jitter phenomenon when operation is carried on with two clock messages in different preriod includes the following steps: monitoring phase relation between two clock messages: starting transmission of multiset of wave form sampling stored in advance corresponding to each rising wave range of the first clock message and there will be a phase difference existing between any two sets of wave form sampling; exporting wave form sampling for each set corresponding to rising wave range of the second clock message and convertnig one set selected out from multiset of wave form sampling stored in advance according to phase relation into analog message. A digital-analog converter is composed of phase monitor, multiple wave form sampling mater, multiplexer and a digital-analog conversion circuit.

The invention discloses a method for framing and modulating wireless multimedia broadcast signals, which is a framing and modulating scheme mixing a time domain with a frequency domain. The method for framing and modulating wireless multimedia broadcast signals has a signal generation mode and a signal selection method which are easy to process and recover an original signal obtaining an OFDM (Orthogonal Frequency Division Multiplexing) signal at a receiver end, and has the advantages of being low in peak average power ratio, short in synchronization time, resistant to channel fading, capableof controlling various businesses, etc.

The invention discloses a method for framing and modulating anti-fading wireless multimedia broadcast signals, which is a framing and modulating scheme that time domains and frequency domains are mixed. The method for framing and modulating the anti-fading wireless multimedia broadcast signals disclosed by the invention has the advantages of low peak-to-average power ratio, short synchronization time, anti-fading property, controllable multi-service and the like.

The invention discloses an anti-interference wireless multimedia mobile broadcast signal framing modulation method, which is a time domain/frequency domain combined framing modulation scheme. The anti-interference wireless multimedia mobile broadcast signal framing modulation method has the advantages of low peak-to-average power ratio, short synchronization time, resistance to the influence of noises, multi-service controllability and the like.

The invention discloses a multimedia broadcasting wireless signal anti-interference framing modulation method which is a time domain and frequency domain mixed framing modulation scheme. The multimedia broadcasting wireless signal anti-interference framing modulation method provided by the invention has the advantages of low peak average power ratio, short synchronizing time, anti-interference, capability of controlling multiple services, and the like.

The invention discloses an anti-interference wireless signal transmission method for a digital broadcast, and relates to a mixed framing modulation scheme of the time domain and the frequency domain. According to the training sequence optimization design, the signal generating scheme and the signal selecting method of the anti-interference wireless signal transmission method for the digital broadcast, OFDM signals can be processed and recovered at a receiver end easily to obtain original signals of the OFDM signals. The anti-interference wireless signal transmission method for the digital broadcast has the advantages of being low in peak-to-average power ratio, short in synchronization time, resistant to channel fading, multiple in controllable service and the like.

The invention discloses a single-frequency-network anti-noise mobile digital broadcast signal transmission method which is a transmission scheme mixing a time domain, a frequency domain and a spatial domain. By using the single-frequency-network anti-noise mobile digital broadcast signal transmission method of the invention, PAPR is low, synchronization time is short, noise can be resisted, and aplurality of services can be controlled and so on.

The invention discloses an anti-interference wireless multimedia broadcast signal framing modulation method, which is a time domain/frequency domain combined framing modulation scheme. The anti-interference wireless multimedia broadcast signal framing modulation method has the advantages of low peak-to-average power ratio, short synchronization time, anti-interference performance, multi-service controllability and the like.

The invention discloses a robust mobile signal framing modulation method for a multimedia broadcast single frequency network, and relates to a mixed framing modulation scheme of the space domain, the time domain and the frequency domain. According to the training sequence optimization design, the signal generating scheme and the signal selecting method of the robust mobile signal framing modulation method for the multimedia broadcast single frequency network, OFDM signals can be processed and recovered at a receiver end easily to obtain original signals of the OFDM signals. The robust mobile signal framing modulation method for the multimedia broadcast single frequency network has the advantages of being low in peak-to-average power ratio, short in synchronization time, resistant to channel fading, multiple in controllable service and the like.

The invention discloses a method for framing and modulating anti-interference wireless multimedia broadcast signals in a single frequency network. The method provides a framing and modulating scheme mixing a space domain, a time domain and a frequency domain. According to a training sequence optimal design, a signal generation pattern and a signal selection method of the method for framing and modulating the anti-interference wireless multimedia broadcast signals in the single frequency network, an original signal of an OFDM signal can be easily obtained through processing and recovery on a receiver terminal. The method for framing and modulating the anti-interference wireless multimedia broadcast signals in the single frequency network has the advantages that the peak-to-average power ratio is low, synchronization time is short, channel fading is prevented, and multiple services can be controlled.

The invention discloses a robust transmission method of digital broadcast mobile signals, which is a mixed transmission scheme of time domain and frequency domain. The method has the advantages of low PAPR (peak-to-average power ratio), short synchronous time, robustness, multiple controllable services and the like.