40results about How to "Avoid nonlinear distortion" patented technology

A random access channel transmission method in which a user terminal selects a preamble pattern from among a plurality of known preamble patterns and transmits that preamble pattern to a base station, where that transmission method comprises: a step of dividing a cell into a plurality of areas, and setting one or more preamble patterns and the number of repetitions for transmitting the preamble pattern for each area; and a step wherein a user terminal that exists in an are close to the base station transmits a specified preamble pattern one time, and a user terminal that exists in an area far from the base station transmits another specified preamble pattern a plurality of times.

The invention discloses a DC deviation correcting method and device. The method comprises the steps of simulating a gain gear and a local oscillator frequency sections for the DC deviation value of a receiver; performing the gradually approaching algorithm during electrically initializing a receiver chip to finish the DC deviation detection of all simulated gain gear and the local oscillator frequency sections; storing the detected DC deviation values into a storage unit; automatically moving out the corresponding current DC deviation value from the storing unit according to the current simulated gain gear and the local oscillator frequency sections; performing the first-stage DC deviation correction before an amplifier and an ADC; performing the second-stage DC deviation value detection before a received usable signal reaches a second-stage DC deviation detecting point; subtracting the second-stage DC deviation value from the usable signal when the received usable signal arrives. The method and the device have the advantages that the dynamic ranges of the amplifier and the ADC cannot be reduced, and the real-time performance is high; the method and the device can be widely applied to the field of radio frequency communication.

The invention discloses a PLL filter. A radio frequency intrinsic signal the frequency of which is the same as the frequency of a final radio frequency output signal is connected with an intrinsic drive module in an external connection way to generate two paths of quadrature radio frequency intrinsic signals, then a baseband signal I and Q components connected in the external connection way are performed with frequency up-conversion by a quadrature mixer, a modulation signal modulated to the radio frequency carrier frequency is obtained and directly used as the input of a radio frequency limiter, the other input of the radio frequency limiter is a feedback signal of the final radio frequency output signal, the two paths of input signals are limited by the radio frequency limiter, then the phases of the two paths of input signals are compared according to the frequency of the radio frequency by a radio frequency phase detector, an upper charge signal or a lower discharge signal is generated to control the output of a fully differential charge pump, fully differential control voltage is output to control the oscillation frequency of a differential voltage controlled oscillator via a fully differential low-pass filter, and the final radio frequency output signal is output. The PLL filter has the advantages of small nonlinear distortion and little stray emission in the output frequency spectrum.

The invention discloses a power operation monitoring system of a 5G communication base station. The system comprises a power operation acquisition module, a control module and a wireless transmissionmodule. The power operation acquisition module comprises a power parameter acquisition circuit, an operational amplifier frequency selection circuit, a measurement protection circuit and a peak detection circuit. An operational amplifier AR1 in the operational amplifier frequency selection circuit carries out secondary amplification on a detection signal, and nonlinear distortion generated by signal amplification is effectively avoided; meanwhile, a third-order band-pass filter is added for frequency selection, and noise interference mixed in the operational amplifier process is well eliminated. A measurement protection circuit and a peak detection circuit are designed to measure two key parameters of the frequency and the amplitude of a detection signal respectively; an ARM microcontroller transmits the acquired data to the monitoring server through the GPRS wireless transmission module for monitoring and management, so the power operation of the 5G communication base station is remotely monitored, and the reliability, the fault diagnosis and the system monitoring capability are very good.

The invention provides a transmission system of network data. The transmission system of the data comprises a data transmission front end, a transmission network, an access network and a data receiving terminal. The data transmission front end comprises a convergence switch with a transceiver port being arranged to be used only for sending mandatorily, and the convergence switch is used for encoding and internet protocol (IP) packing of data such as audio and video and transmitting an IP data package out through the convergence switch in an IP broadcast mode or a multicast mode. The transmission network is used for transmitting the IP package in a rate of 1 Gigabyte (Gb) or more than 1 Gb in single and transparent modes. The access network comprises a first switch of a broadcast switch or a multicast switch, and the access network is used for acquiring the IP package from the transmission network through the first switch. The data receiving terminal is used for acquiring the IP package from the access network and unpacking and encoding for the IP package so that the data of the audio and the video can be displayed.

An embodiment of the invention provides a data receiving terminal in a network data transmission system. The network data transmission system further comprises a front data transmission terminal, a transmission network and an access network. The front data transmission terminal comprises a convergence switch, a transceiving port of the convergence switch is forcedly set to transmit only, and the front data transmission terminal is used for encoding and IP (internet protocol) packing of audio-video data and the like and outputting an IP data packet in an IP broadcasting or multicast mode via the convergence switch. The transmission network is a cable television broadcasting network which is used for unidirectional and transparent transmission of the IP packet at the speed of 1Gb or above. The access network comprises a first switch and is used for obtaining the IP data packet from the transmission network via the first switch which is a broadcasting switch or a multicast switch. The data receiving terminal is used for obtaining the IP data packet from the access network and unpacking and decoding the IP data packet so as to play the audio-video data.

The invention discloses an SC-FDMA-based visible light communication system, and belongs to the technical field of visible light communication. The SC-FDMA-based visible light communication system comprises a modulator, a transmitting end, a receiving end and a demodulator; the transmitting end is composed of a transmission driving circuit and an LED; the receiving end is composed of a post-amplification circuit, a basic amplification circuit and a photoelectric tube; the photoelectric tube is used for converting received optical signals into electric signals; the basic amplification circuit is used for amplifying weak signals after the photoelectric tube converts the optical signals into the electric signals; and the post-amplification circuit is composed of a program control amplification circuit, an automatic gain control AGC circuit and a manual adjustment combined feedback circuit. By means of the SC-FDMA-based visible light communication system disclosed by the invention, the uplink multiple access problem of the visible light communication system can be solved; therefore, multiple users correspond to one receiving end; and each user distributes different sub-carriers to perform individual modulation, and finally to be superposed on a light path.

The invention discloses a microphone gain adjustment method, a device, a system and a storage medium. The method comprises the following steps: acquiring a volume value of a sound signal played by a loudspeaker; judging whether the volume value is greater than a preset volume threshold; and if yes, performing reduction processing on the preset microphone gain according to the volume value of the played sound signal, and setting the target gain obtained after reduction as the current microphone gain. According to the microphone gain adjustment method provided by the invention, when the volume value of the sound signal played by the loudspeaker is greater than the preset volume threshold value, the preset microphone gain is reduced, the smaller microphone gain is set as the current microphone gain, non-linear distortion generated after the sound signal with larger volume emitted by the loudspeaker is picked up and amplified by the microphone is avoided, the accurate user sound signal canbe obtained, and the effective awakening of the intelligent sound box is further ensured.

The invention discloses a triangular prism type fiber grating acceleration detector based on a hollow-core column type elastic-mass sensitive structure. The triangular prism type fiber grating acceleration detector comprises a hollow-core triangular prism having a base with a through hole and an open upper end; and an inertial mass block and a Bragg fiber grating are arranged at the top of the hollow-core triangular prism. According to the invention, on the basis of the wavelength sensing principle of the fiber grating, the triangular prism hollow-core tube of the detector is stretched or compressed in a vertical direction under the inertia effect of the mass block under the action of the external excitation vibration signal; and thus the packaged grating makes the axial strain and thus the wavelength makes drift. Detection of an acceleration signal in a vertical direction is realized by detecting the change of the grating wavelength.

The invention discloses a low-noise wireless audio transmitting system based on a linear amplification circuit. The system is characterized by mainly comprising a processing chip U and a capacitor C8. A negative electrode of the capacitor C8 is connected with a resistor R7 and then a GND pin of the processing chip U, and a positive electrode of the capacitor C8 is connected with a resistor R4 and then used as an audio signal input end. The system can process an audio signal. The system can improve the amplitude of the audio signal, thereby compensating for the weakness of the audio signal caused during long-distance transmission and improving the hearing effect of the receiving end. Meanwhile, the system can eliminate the current noise, prevent the current noise from interfering the audio signal, improve the sharpness of the audio signal, and improve the quality of signal transmission. The system can also make the amplitude of an output audio signal proportional to the amplitude of an input audio signal, avoid non-linear distortion of the audio signal, improve the stability of the audio signal, and thus facilitate long-distance transmission of the audio signal.

The invention discloses an audio amplitude limiting circuit. The audio amplitude limiting circuit comprises a sampling circuit, an amplification circuit, a rectification circuit, a delayed adjustment circuit, an impedance matching circuit, and a light sensitive resistor, wherein the sampling circuit is used for sampling an input audio signal and outputting the sampled audio signal to the amplification circuit; the sampled audio signal is amplified through the amplification circuit, and the amplified audio signal is output to the rectification circuit; the amplified audio signal is rectified through the rectification circuit, and the rectified audio signal is output to the delayed adjustment circuit; an amplification limiting control starting time and an amplification limiting release time for the audio signal are adjusted through the delayed adjustment circuit; and the audio signal subjected to the amplitude limiting adjustments is output to the light sensitive resistor for splitting. The audio amplitude limiting circuit adopting the technical scheme has the advantage that the problems of a limited amplification limiting amplitude and existence of various distortions in the traditional amplification limiting circuit are solved through driving on the light sensitive resistor.

The invention discloses a CPM-based RCM encoding method, a decoding method and a system, and belongs to the technical field of rate adaptive transmission in wireless communication. The method comprises the following steps: enabling an RCM encoding symbol to obtain a constant envelope signal with the peak-to-average ratio of 0dB through CPM modulation; internal iteration is carried out for multipletimes by adopting a BP method; continuously updating the message from the coding symbol to the random signal and the message from the random signal to the coding symbol; and when the maximum number of iterations is reached, outputting the prior probability corresponding to the coded symbol and transmitting the prior probability to a CPM demodulator, updating the maximum posteriori probability ofthe coded symbol according to the transmitted prior probability of the coded symbol, transmitting the updated maximum posteriori probability to an RCM decoder, updating a message from the coded signalto a random signal, and obtaining the probability that the random signal values are 0 and 1. According to the invention, the problem that the RCM high-power signal falls in the nonlinear region of the power amplifier to generate nonlinear distortion is avoided.