34results about How to "Eliminate Phase Noise" patented technology

A differential voltage controlled oscillator (VCO) employed in a frequency synthesizer used as a local oscillator of a wireless communication on-chip transmitter / receiver is provided. More particularly, a differential current negative feedback VCO equipped with a current-current negative feedback circuit that suppresses low- and high-frequency noise is provided. A differential current negative feedback VCO includes a resonator determining oscillation frequency, and an oscillator generating negative resistance. In the oscillator of the differential current negative feedback VCO, transistors Q1 and Q2 form a cross-coupled pair, and negative resistance is generated by positive feedback of the cross-coupled pair. And, transistors Q1 and Q3 together with an emitter resistor and a capacitor form a current negative feedback part, and transistors Q2 and Q4 together with an emitter resistor and a capacitor form another current negative feedback part which is disposed opposite to a resonator. Thus, the VCO operates differentially. In the oscillator of the differential current negative feedback VCO, emitter noise currents generated by base noise voltages of Q1 and Q2 induced by low- and high-frequency noise sources in the bases of Q1 and Q2 are sampled by emitter resistors, amplified through bases of Q3 and Q4, and thus return to the bases of the Q1 and Q2 and suppress the base noise voltages. Measurement of the phase noise of the differential current negative feedback VCO reveals a phase noise reduction of approximately 25 dB compared to a conventional differential VCO.

One aspect of the present invention is a frequency conversion circuit having a pair of local oscillators. The local oscillators are frequency synthesizers based on an external frequency reference. The frequency conversion circuit is configured to perform a frequency conversion to an input signal equal to a frequency difference of signals from the pair of local oscillators; to generate an oscillator frequency difference signal; to generate an error signal using the oscillator frequency difference signal and an internal reference signal derived from the external frequency reference; and to adjust a phase of one of the pair of oscillators using the error signal. The above-described frequency conversion circuit embodiment essentially eliminates divider phase noise such as that generated by traditional prescalers. In addition, the use of two local oscillators provides a frequency conversion circuit capable of wide-range frequency conversion and high resolution. This frequency conversion circuit embodiment is suitable for receivers as well as transmitters, and is particularly suitable for digital television systems.

Disclosed is an optical sensing device including a source unit providing a beam of light with continuously modulated phase retardation between p- and s-polarization components of the light by employing a LCM; a reference unit receiving a first part of the light to provide a reference signal; a SPR sensing unit receiving a second part of the light to induce a phase retardation change between the p- and s-polarization components due to SPR associated with a sample; a probe unit receiving the light after SPR to provide a probe signal; and a detection unit connected to the reference unit and the probe unit to detect characteristics of the sample by comparing the reference signal with the probe signal. By using active phase modulation technologies and differential phase measurement, it is possible to fulfill chemical and biological detection.

The invention discloses an optical signal receiving device, an optical signal receiving method, and a coherent optical transmission system with the device, relating to the field of coherent optical transmission systems. The optical signal receiving device comprises: a local laser, two polarization beam splitters, two polarization beam combiners, two photodetectors, two analog to digital converters, and a digital signal processing unit, wherein the digital signal processing unit comprises a self-beating frequency noise eliminating module configured to eliminate the influence of the self-beatingfrequency of the signal on the system performance, and a phase noise compensation module configured to eliminate the phase noise of the signal by utilizing the phase noise compensation algorithm. Theinvention is capable of solving the problem of high cost of laser in the existing coherent optical transmission system.

A differential voltage controlled oscillator (VCO) employed in a frequency synthesizer used as a local oscillator of a wireless communication on-chip transmitter / receiver is provided. More particularly, a differential current negative feedback VCO equipped with a current-current negative feedback circuit that suppresses low- and high-frequency noise is provided.A differential current negative feedback VCO includes a resonator determining oscillation frequency, and an oscillator generating negative resistance. In the oscillator of the differential current negative feedback VCO, transistors Q1 and Q2 form a cross-coupled pair, and negative resistance is generated by positive feedback of the cross-coupled pair. And, transistors Q1 and Q3 together with an emitter resistor and a capacitor form a current negative feedback part, and transistors Q2 and Q4 together with an emitter resistor and a capacitor form another current negative feedback part which is disposed opposite to a resonator. Thus, the VCO operates differentially.In the oscillator of the differential current negative feedback VCO, emitter noise currents generated by base noise voltages of Q1 and Q2 induced by low- and high-frequency noise sources in the bases of Q1 and Q2 are sampled by emitter resistors, amplified through bases of Q3 and Q4, and thus return to the bases of the Q1 and Q2 and suppress the base noise voltages. Measurement of the phase noise of the differential current negative feedback VCO reveals a phase noise reduction of approximately 25 dB compared to a conventional differential VCO.

The present disclosure relates to a method and a device for a terminal performing decoding in a wireless communication system. According to the present disclosure, a method and a device may be provided, the method comprising a step for receiving a first demodulation reference signal (DMRS) and a second DMRS configured according to particular patterns from a base station via DMRS symbols, wherein the first DMRS and the second DMRS are respectively transmitted on particular antenna ports and are positioned on the same time axial symbol as that of at least one other DMRS transmitted on another antenna port, and the position of the time axial symbol of the second DMRS is determined according to a slot format or the last symbol on which downlink data is transmitted, and data is decoded using at least one of the first DMRS or the second DMRS.

The invention discloses a method and device for digitally demodulating a phase generated carrier by adopting analog front end. The device is characterized by consisting of analog demodulation, digital compensation and digital demodulation modules. The method comprises four steps of frequency mixing of an interference signal with a primary-frequency carrier signal and a doubled-frequency carrier signal respectively and carrying out of low-pass filtering, digital compensation, elimination of random phase fading, reduction of a detected signal, and the like. Compared with an existing digital demodulation method, the method can be used for obviously reducing a demodulation response time; a frequency mixing algorithm and a low-pass filtering algorithm in the existing digital demodulation are removed; the algorithm complexity is decreased; the demodulation precision is improved; the problem that a dynamic range is limited by the existing digital demodulation method is solved.

The present invention relates to an apparatus and method for feedforward-type phase noise elimination in a portable terminal, which detect and eliminate phase-reversed phase noise by subtracting a GSM transmission signal, passed through the power amplifier of a GSM transmission device, from a GSM transmission signal, extracted from an upstream stage of the power amplifier, so that phase noise signals attributable to high-power transmission signals.

A CMOS cross-coupled differential voltage controlled oscillator is provided with a pair of oscillator outputs. The oscillator includes a current control unit, a first cross-coupled differential pair, an inductor unit, a capacitor unit, a second cross-coupled differential pair and a voltage controller. The current control unit is coupled between a relatively-high voltage and a relatively-low voltage. The first cross-coupled differential pair, the inductor unit, the capacitor unit and the second cross-coupled differential pair are coupled between the pair of oscillator outputs. According to the present invention, the inductor unit is provided with a midway node. The voltage controller is coupled and powered by the midway node.

The invention discloses a polarization modulation based phase noise elimination method in a massive MIMO-OFDM (Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing) uplink system,and belongs to the technical field of wireless communication. According to the invention, transmitting and receiving ends of the massive MIMO-OFDM uplink system are designed; at the transmitting end,orthogonal dual-polarization antennas are deployed and a polarization modulation signal is transmitted; and at the receiving end, a pair of orthogonal dual-polarization antennas are deployed and thepolarization modulation signal is received and demodulated. At the receiving end, by zero-forcing receiving, in a case, distribution characteristics of power and noise of sub-carrier interference terms in phase noise of the receiving end after a polarization modulation scheme is adopted are argued, and finally, a result that the phase noise applied to the polarization modulation received signal can be transferred to additive noise is proved, so that influence of the phase noise is eliminated. The polarization modulation based phase noise elimination method disclosed by the invention solves a problem of reduction of traversal capacity, which is caused by influence of the phase noise on the massive MIMO-OFDM uplink system, and meanwhile, also solves problems of high investment and increase of a terminal cost price, which are caused by redesign of a low-phase-noise local oscillator.

The invention provides an optical fiber vibration measurement device and method with a light source frequency shift calibration auxiliary channel. The invention relates to the field of optical fiber distributed vibration measurement. In a traditional phase-sensitive optical time domain reflection measurement device, a frequency shift calibration auxiliary channel is added as an auxiliary channel of the measurement device to completely compensate frequency drift of a light source and eliminate phase noise of a laser. In a feed-forward loop of a light source noise suppression feed-forward structure, two paths of mutually orthogonal interference light signals are obtained based on an interferometer and a 90-degree optical mixer, respectively output to a photoelectric balance detector 1 and aphotoelectric balance detector 2, and converted into two paths of interference electric signals. The influence of random change of an optical frequency initial phase on a measurement result when the optical frequency drift amount is measured based on a single signal is avoided, and the measurement precision of an external vibration signal is improved.

A mixer with dynamic intermediate frequency in a RF front-end to dynamically adjust the intermediate frequency and method thereof are described. The radio-frequency front-end comprises a band-pass filter, an amplifier, a first mixer unit and a second mixer unit. The band-pass filter receives first RF signal to generate second RF signal. The amplifier amplified the second RF signal and output third RF signal (SRF). The first mixer unit is used to mix the third RF signal (SRF) with first frequency signal (S1) to down convert the third RF signal (SRF) to an intermediate frequency (IF) and outputs an IF signal (SIF). The second mixer unit is connected to the first mixer unit in a cascode configuration and has I-channel and Q-channel mixers to transform IF signal (SIF) to an I-channel signal (SI) and a Q-channel signal (SQ). The radio-frequency front-end further comprises a dividing unit for receiving an oscillator signal (S0) to generate the first, the second and the third frequency signals (S1, S2, and S3) such that the frequency of the first frequency signal (S1) substantially equals the frequency of the oscillator signal (S0) divided by two's power of a first non-negative integer (N1), the frequency of the second and the third frequency signals (S2, and S3) substantially both equals the frequency of the oscillator signal (S0) divided by two's power of a second non-negative integer (N2), and the second frequency signal (S2) is approximately 90 degree out of phase with respect to the third frequency signal (S3).

The invention belongs to the technical field of optical fiber communication and optical network transmission and specifically relates to an electrical absorption modulation laser device-based high frequency vector radiofrequency signal generation system and a precoding method. The system mainly consists of an integrated electrical absorption modulation laser device, an optical cross wavelength division multiplexer and a photoelectric detector. Precoding operation is performed based on different modulation formats, magnitude of offset voltage and driving signals of the electrical absorption modulation laser device is set, optical signals are modulated, the optical cross wavelength division multiplexer is adopted, detection operation is performed via the photoelectric detector, and finally optical vector radiofrequency signals that are robust for optical frequency noise and phase noise are finally stably generated. After the optical vector radiofrequency signals that are pre-coded are detected via the photoelectric detector, optical vector radiofrequency signals can still processed via an electric coherent reception and digital signal processing algorithm, transmission rates of a communication system and sensitivity of a receiver can be improved, and transmission performance can be enhanced.

In one embodiment, the present invention includes a method for digitizing a phase noise value indicative of a level of phase noise present in a LO signal and downconverting an RF signal to a second frequency signal using the LO signal. This downconversion can cause the phase noise to be transferred to the second frequency signal. The method may thus further include removing the phase noise from the second frequency signal using the digitized phase noise value.

The present invention relates to an apparatus and method for feedforward-type phase noise elimination in a portable terminal, which detect and eliminate phase-reversed phase noise by subtracting a GSM transmission signal, passed through the power amplifier of a GSM transmission device, from a GSM transmission signal, extracted from an upstream stage of the power amplifier, so that phase noise signals attributable to high-power transmission signals.

The invention discloses an interference type optical fiber vector hydrophone with a reference interferometer. The interference type optical fiber vector hydrophone comprises a mass block, an elastic cylinder, an optical fiber interferometer and a shell used for placing the mass block, the elastic cylinder and the optical fiber interferometer. According to the invention, the reference interferometer and the sensing interferometer are packaged in the shell of the same hydrophone. When the hydrophone is influenced by temperature and other external environments, the hydrophone can be heated; low-frequency random drifts generated by phase signals of the reference interferometer and the sensing interferometer are highly similar. In practical application, the phase noise of the reference interferometer and the phase noise of the sensing interferometer caused by the laser are highly related, so that the phase noise of the signals of the sensing interferometer can be eliminated by performing signal processing on the signals of the reference interferometer and the sensing interferometer.

The invention relates to a mobile station, a method and device for improving the sensitivity of the mobile station. The method includes the following steps that: first pixel clock signals of mobile station display peripheral equipment are obtained; a channel used by next time slot data to be received by a mobile station receiver is obtained; whether the obtained channel is in the range of channels which are interfered by the first pixel clock signals of the mobile station display peripheral equipment is judged; and when the obtained channel is in the range of the channels which are interfered by the first pixel clock signals, second pixel clock signals are adopted as the clock signals of the mobile station display peripheral equipment. With the method provided by the above technical schemes adopted, the sensitivity of the mobile station can be effectively improved, and the use experience of a user can be enhanced.

The invention discloses an optical phase demodulation method and system based on polarization-division receiving. The method comprises the following methods that I / Q demodulation is carried out on optical signals collected by two sensing points, and signal polarization receiving is carried out by using a polarization receiving device to obtain corresponding signal components; an optical phase vector is constructed according to the corresponding signal components; a birefringence phase vector is determined according to the optical phase vector, and the phase difference is normalized; and afterthe birefringence phase vector is compensated, the phase change between the two sensing points is obtained through vector synthesis. According to the invention, a birefringence phase vector is compensated, so that the influence of polarization fading on signal demodulation is reduced, and the system stability is improved; and the I signal and the Q signal are subjected to orthogonal decomposition,and optical signals are converted into a vector to realize depolarized phase demodulation, so that the birefringence phase difference can be accurately estimated, and the accuracy of signal restoration is improved.

A clock signal outputting method in which either a clock signal based on a signal from the outside or an alternative clock signal from a fixed oscillator is selected and outputted, wherein, when the clock signal is selected to be outputted, the fixed oscillator is put into non-operating state, and when any error occurs in the clock signal, the fixed oscillator is operated to output the alternative clock signal.

The invention discloses a Brillouin optical time domain analysis system based on Brillouin phase shift demodulation, which is composed of two parts: optical path detection and circuit demodulation; The light is generated by cascade modulation of Mach-Zehnder modulator and phase modulator, the light generated by the first stage modulation is used as the light interacting with the pump, the light generated by the second stage is used as auxiliary light to eliminate phase noise, and the receiving end is coherently detected; The circuit uses envelope detection to demodulate the signal. The system of the invention is simple, easy to implement and easy to adjust; single channel, low sampling rate, less data volume; high Brillouin phase measurement accuracy and high stability can be obtained.

A detection apparatus and method for noise intensity and a coherent optical receiver where the detection method includes: preprocessing a received signal to obtain a pilot sequence contained in the received signal; removing a phase noise of a receiving pilot sequence by using a known transmitting pilot signal; calculating a noise power density of the receiving pilot sequence with no (or without) phase noise within a predetermined spectral width near a pilot frequency; and calculating power of a linear noise of the received signal based on a bandwidth of the received signal and the noise power density within the predetermined spectral width. Hence, linear noises and nonlinear noises may be split efficiently without introducing much complexity, and information on intensities of various noises may be obtained.

The present invention discloses an oudoor field RCS measurement method, which comprises the steps of acquiring at least one group of echo signals, wherein any group of echo signals comprises a target intermediate-frequency (IF) echo signal and a scaling body IF echo signal; for any group of echo signals, conducting the analog-to-digital conversion on the target IF echo signal in the above group of echo signals to generate a first digital signal, conducting the analog-to-digital conversion on the scaling body IF echo signal in the above group of echo signals to generate a second digital signal; conducting the fast Fourier transformation on the first digital signal to obtain a first complex-quantity signal, obtaining a first electric field strength in accordance with the first complex-quantity signal; conducting the fast Fourier transformation on the second digital signal to obtain a second complex-quantity signal, obtaining a second electric field strength in accordance with the second complex-quantity signal; calculating a candidate RCS according to the first electric field strength and the second electric field strength; on the condition that only one group of echo signals is acquired, adopting the candidate RCS as a target RCS. According to the technical scheme of the invention, the phase noise and the attenuation in the oudoor field RCS, caused by the external interference, can be eliminated, so that the RCS measurement error is reduced.

An optical relay system is provided, which includes a first optical signal distribution device (101), a phase detection device (103), an amplitude regeneration device (102), and a phase regeneration and load device (104). An optical relay method is further provided, which includes the following steps. A received input signal is divided into two paths; phase information of one path of the input signal is extracted, and is converted to an amplitude modulated signal; an amplitude of the other path of the input signal is restored, so as to generate an amplitude regenerated signal; a phase is loaded on the amplitude regenerated signal by using the amplitude modulated signal, so as to generate a phase regenerated signal. The system and method eliminate a phase noise of the signal in a transmission process, improve a transmission performance of the signal, and realize a simple implementation method.

A method for realizing a self-oscillating multi-carrier optical fiber light source and a multi-carrier optical fiber light source system: establish a multi-carrier optical fiber light source based on a cyclic frequency shift loop; amplify the optical signal output by the multi-carrier optical fiber light source in the optical domain; Perform longitudinal mode selection processing in the signal optical domain; convert the optical signal after longitudinal mode selection processing into corresponding electrical signals of different frequencies; perform electrical domain filtering on the electrical signal; perform electrical domain amplification on the filtered electrical signal; The final electrical signal is fed back to the frequency shifter in the cyclic frequency shifting loop of the multi-carrier fiber optic light source, which is used to drive the frequency shifter to control the frequency shift of the optical signal, so that the multi-carrier fiber optic light source outputs an optical signal with a set frequency interval. Part of the above optical signals returns to step 2 for the next cycle, and the other part of the optical signals is used as the multi-carrier output of the entire system. The invention has the characteristics of large output signal carrier coverage, flat power, low phase noise, and no external radio frequency driving source.

The invention discloses an inductor-capacitor (LC) oscillator with basically constant variable capacitance in an oscillation period. The LC oscillator comprises a resonance network consisting of an inductor L and a self-adaptive compensation variable capacitor, a complementary cross-coupling negative resistance amplifier and a bias current source, wherein the variable capacitor is a self-adaptive compensation varactor (AC-Varactor). By dynamically compensating the variable capacitance of the AC-Varactor, variable capacitance variation caused by amplitude variation of output waveform is avoided, and frequency modulation caused by the amplitude variation is avoided, so that phase noise performance deterioration caused by amplitude noise is minimized. The LC oscillator overcomes the defects that in one oscillation period, the variable capacitance can change the oscillation frequency along with the change of voltage at two ends, and the oscillator phase noise performance is decreased by an amplitude modulation to frequency modulation (AM-FM) process; and the LC oscillator with the basically constant variable capacitance in the oscillation period has good phase noise performance and can be widely applied to wireless communication systems.