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230results about How to "Accurate demodulation" patented technology

Method with strong anti-multi-path capability for processing moveable underwater sound communication signal

The invention relates to a method with strong anti-multi-path capability for processing moveable underwater sound communication signals, including two parts, namely a transmitter processing method and a receiver processing method, wherein the transmitter processing method includes the operations of error correction of coding, data packing, digital interpolation, base band shaping wave filtering, upper modified frequency modulation, and the like; and the receiver processing method includes the operations of digital wave filtering, frame synchronous judgment, preliminary compensation of Dopplerfrequency shift, lower modified frequency modulation, bit synchronous judgment, fine compensation of Doppler frequency shift, digital equalization, error correction of decoding, etc. The invention carries out the intercrossing treatment on technologies of synchronous judgment, compensation of Doppler frequency shift, compensation of multi-path effect, and the like, and guarantees that under the environment of strong Doppler frequency shift, the system can realize the accurate synchronism of signals and carries out real-time estimation and compensation on the effect of strong Doppler frequencyshift; and the adopted blind equalization method can carry out effective tracking compensation on the time varying multi-path effect of an underwater sound signal channel, thereby greatly increasing the integral stability and the bit error rate performance of an underwater sound communication system and enduing the system with the capability of reliable communication during movement.
Owner:NAVAL UNIV OF ENG PLA

Reception circuit, radio-controlled timepiece, and reception circuit control method

A reception circuit can receive a plurality of standard time signals and has a reception means for selectively receiving and demodulating any one of the plural standard time signals, and a control means for outputting a control signal that controls the reception means. The reception means includes a signal amplifier unit for amplifying a reception signal representing the received standard time signal; a signal extraction unit for extracting a signal of a specific frequency from the amplified reception signal; a rectifier unit for rectifying the extracted signal of the specific frequency; and a demodulation unit for demodulating the rectified signal of the specific frequency. The signal extraction unit includes a plurality of crystal filters corresponding to the frequencies of the plural standard time signals; a plurality of parallel capacitances corresponding to the plural crystal filters and parallel connected to the plural crystal filters; a filter switching unit for switching the plural crystal filters based on the control signal; and a parallel capacitance switching unit for switching the plural parallel capacitances based on the control signal. The control means outputs to the filter switching unit and the parallel capacitance switching unit a control signal denoting the switch states enabling the reception means to receive the standard time signal.
Owner:SEIKO EPSON CORP

Wireless communication system, receiver, transmitter, wireless communication method, receiving method, and transmitting method

A system that combines MIMO spatial multiplexing and dual polarization transmission is provided. The system is constructed with a simple circuit configuration, whereby a wireless communication system which accurately demodulates signals that are multiplexed doubly, both spatially and in polarization, is provided. The wireless communication system is a MIMO communication system that uses a plurality of antennas to form a plurality of fixed transmission channels, and includes a transmitting section and a receiving section. The transmitting section performs MIMO spatial multiplexing as well as dual polarization transmission of transmitting two independent signals in the same band by using two mutually orthogonal polarizations of radio waves as signals to be transmitted from respective antennas on a transmitting side. The receiving section includes an inference canceller and a MIMO signal processing circuit that is connected to the interference canceller. The interference canceller performs signal processing for eliminating an interference component between the polarizations by adaptive control on signals received by respective antennas on a receiving side. The MIMO signal processing circuit performs signal processing for MIMO spatial demultiplexing independent of the signal processing of the interference canceller.
Owner:NEC CORP

Method and device for transmitting demodulation reference signal, as well as method and device for receiving demodulation reference signal

The invention discloses a method and a device for transmitting a demodulation reference signal, as well as a method and a device for receiving a demodulation reference signal. The transmitting method comprises the following steps: determining a PRB (program require block) which is subjected to subcarrier migration with the PRB of a second base station among the PRB included in a sub frame to be sent of a first base station when the first base station and the second base station execute cooperative transmission; performing frequency shift on RE (receiving equipment) carried with a DM-RS (demodulation reference signal) in the direction from the DC (direct current) subcarrier of the second base station to the DC subcarrier of the first station, in the time frequency resource consisting of the determined PRB (program require block), according to the amount of the migration subcarrier of the determined PRB; in the PRB included in the sub frame, mapping the DM-RS to the RE for carrying the DM-RS; and then sending the sub frame to a user terminal. By utilizing the technical scheme, the problems in the prior art that interferences of a data symbol and a pilot symbol are likely to occur on the PRB subjected to subcarrier migration, when two base stations execute cooperative transmission, and the error code rate is very high when the user terminal demodulates the DM-RS are solved.
Owner:CHINA MOBILE COMM GRP CO LTD

Resource allocation

ActiveUS20100069081A1Increase possibility of correct demodulationIncrease possibilityAssess restrictionOrthogonal multiplexData channelControl channel
Resource allocation information is signalled to user devices (UE1, UE2, UE3, UE4) in a mobile telecommunications communications system in which each user device is allocated plural resource allocations (RB) in a TTI (50) by, for each user device, providing information (I1) regarding a selected resource allocation allocated to that user device in a control channel (L1, L2, L3, L4) and providing information (I2, I3) regarding at least one other resource allocation allocated to that user device in a data channel (52) in the selected resource allocation. In one example, the selected resource allocation is the first resource allocation (RB1) allocated to that user device (UE1) and information regarding each successive further resource allocation is provided in a data channel in the resource allocation preceding that successive further resource allocation. In another example, the selected resource allocation is the first resource allocation allocated to that user device and information regarding each successive further resource allocation is provided in a data channel in the first resource allocation. In another example, the selected resource allocation is the resource allocation that is indicated to have the best channel quality. The resource allocation information may be provided in the data channel of the one resource allocation as a list of RFI fields or as a bit map.
Owner:NEC CORP

Ultrasonic ranging method and ranging device with high anti-interference performance

InactiveCN103941259AImprove real-time performanceGood self- and cross-correlation propertiesAcoustic wave reradiationSonificationSelf correlation
The invention provides an ultrasonic ranging method and ranging device with high anti-interference performance. Frequency modulation is conducted on a sine wave signal generated by a sine-wave generator through a pseudo code, and transmitting ultrasonic wave is generated and transmitted; echo frequency discrimination demodulation is conducted on the ultrasonic wave echo, so that echo identification is achieved, and the detection is more accurate; moreover, the pseudo code has a good self-correlation characteristic and a good cross-correlation characteristic, and when the pseudo code is applied to the spread spectrum communication, good noise interference-resistant performance and good mutual crosstalk-resistant performance are represented, so that the problem of mutual crosstalk of the ultrasonic wave is solved and the result is accurate; furthermore, the FFT technology is adopted, so that the received wave can be accurately modulated through a few sampling data, frequency resolution is guaranteed, data collecting time of the received wave is shortened, real-time work of the ranging device is greatly improved, and an efficient solution for accurate and rapid ranging and positioning is provided for an autonomous mobile robot.
Owner:CHANGAN UNIV

Low signal-to-noise ratio short frame burst communication open loop demodulation method and device

The invention discloses a low signal-to-noise ratio short frame burst communication open loop demodulation method and a low signal-to-noise ratio short frame burst communication open loop demodulationdevice, and belongs to the technical field of direct sequence spread spectrum demodulation technologies. According to the method, a segmented data processing mode is used for firstly demodulating dispreading data, then performing supply-zero FFT to estimate a frequency offset variation rate and frequency offset and perform compensation. A method of exhaustion is used for accurately estimating andcompensating each frequency offset, the polarity of a frame header is used for performing defuzzification on the phase, to complete correct demodulation of the data. Compared with the prior art, themethod and the device provided by the invention overcome the disadvantages that traditional phase-locked loop coherent demodulation devices are fuzzy in phase and slow in convergence speed, the frequency offset and the frequency offset variation rate can be quickly searched and compensated, the phase discrimination and phase correction can be completed, the short time is ensured, and a direct sequence spreading signal can be normally demodulated under the condition of a low signal-to-noise ratio.
Owner:BEIJING INSTITUTE OF TECHNOLOGYGY
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