261 results about "Quadrature demodulation" patented technology

Apparatus, method and storage medium which can provide at least one first electro-magnetic radiation to a sample and at least one second electromagnetic radiation to a reference, such that the first and/or second electromagnetic radiations have a spectrum which changes over time. In addition, a first polarization component of at least one third radiation associated with the first radiation can be combined with a second polarization component of at least one fourth radiation associated with the second radiation with one another. The first and second polarizations may be specifically controlled to be at least approximately orthogonal to one another.

A wireless communication apparatus receives an quadrature modulated signal, generate a local signal having a frequency different from a center frequency of the quadrature modulated signal, performs quadrature demodulation on the quadrature modulated signal by using the local signal, to obtain an I channel signal and a Q channel signal, performs Fourier transform on the I channel signal and the Q channel signal, to obtain signals in a frequency domain, and calculates a first correction coefficient for correcting phase distortion and amplitude distortion caused by the quadrature demodulation by using pairs of signals among the signals, each of the pairs are located at symmetrical frequency positions with respect to the frequency of the local signal.

A digital IF receiver (DRX) module directly compatible with advanced radar systems such as synthetic aperture radar (SAR) systems. The DRX can combine a 1 G-Sample/sec 8-bit ADC with high-speed digital signal processor, such as high gate-count FPGA technology or ASICs to realize a wideband IF receiver. DSP operations implemented in the DRX can include quadrature demodulation and multi-rate, variable-bandwidth IF filtering. Pulse-to-pulse (Doppler domain) filtering can also be implemented in the form of a presummer (accumulator) and an azimuth prefilter. An out of band noise source can be employed to provide a dither signal to the ADC, and later be removed by digital signal processing. Both the range and Doppler domain filtering operations can be implemented using a unique pane architecture which allows on-the-fly selection of the filter decimation factor, and hence, the filter bandwidth. The DRX module can include a standard VME-64 interface for control, status, and programming. An interface can provide phase history data to the real-time image formation processors. A third front-panel data port (FPDP) interface can send wide bandwidth, raw phase histories to a real-time phase history recorder for ground processing.

A constant amplitude coded bi-orthogonal demodulator demodulates the received constant amplitude bi-orthogonal modulated data, cancels the parity bits to generate the serial data, detects the occurrence of an error by dividing the demodulated data into a plurality of groups of data, outputs the serial data as demodulated data if an error does not occur, sequentially converts bit polarities of data of groups in which an error occurs if the error detector detects the error, compares distances between the received bi-orthogonal modulated data and the constant amplitude coded bi-orthogonal modulated data, and selects, as demodulated data, data of which corresponding bit polarities are changed according to the comparison results. According to the present invention, power consumption is reduced, a power amplifier can be manufactured at an inexpensive cost, interference robustness can be ensured, and data can be transmitted at a high transmission rate and a variable transmission rate.

A vehicular traffic surveillance Doppler radar system and method for use of the same are disclosed. In one embodiment, the system comprises a modulation circuit portion for generating modulated FM signals. An antenna circuit portion transmits the modulated FM signals to a target and receives the reflected modulated FM signals therefrom. A ranging circuit portion performs a quadrature demodulation on the reflected modulated FM signals and determines a range measurement based upon phase angle measurements derived therefrom.

The invention discloses a multi-target radar detection method, comprising steps of transmitting a radar electromagnetic wave, wherein the modulation signals adopted by the electromagnetic wave are a single frequency continuous-wave CW signal and a frequency modulation continuous wave FMCW triangular wave signal, obtaining a reception signal through the radar electromagnetic wave reflected back, performing frequency mixing on the reception signal and the modulation signal to obtain an intermediate frequency signal, obtaining an I/Q signal after performing quadrature demodulation on the intermediate frequency signal, performing matching according to speed information of various targets which is detected by the CW signal and the distance information and speed information of various targets which are detected by the FMCW triangle wave signal after performing complex fast Fourier FFT operation on the I/Q signal to obtain final distance information and speed information of various targets. The multi-target radar detection method is low in cost, simple in realization and high in reliability.

The invention discloses a quadrature demodulation device for an interference type photo-sensor based on pi/2 phase modulation. In the device, light output by a laser is divided into a signal sensing light path and a reference light path through a 1*2 coupler; on the signal sensing light path, a sensing signal output is acquired by a phase sensitive device of a sensing head; on the reference light path, a reference signal output is acquired by a pi/2 phase modulator; the sensing signal output and the reference signal output are combined through a 2*1 light combiner, pass through a photoelectric detector and a low-noise amplifier sequentially and then are sampled by a digital signal processor; and the acquired data is divided into two paths according to odd-even positions and then is subjected to digital quadrature demodulation to acquired a sensing signal required to be demodulated. The device has the advantages of simple phase demodulation structure, simple and effective processing arithmetic, capability of effectively eliminating non-linear influences of devices and the like.

The invention provides a sonar moving target imaging method based on target echo Doppler characteristics, which comprises the following steps of: performing band-pass filtering on echo data of each basic element in a receiving basic array; performing band-pass filtering on each frequency point signal to acquire band-pass data of each frequency point; performing quadrature demodulation on the datasubjected to band-pass filtering of each frequency point to acquire an analytic signal form of a real signal; performing Chebyshev weighting and focusing operation on the echo data subjected to quadrature demodulation of each frequency point; acquiring image data of each frequency point in a polar coordinate system by fast Fourier transform (FFT) beam forming; and performing interpolation mergingon the image data subjected to FFT beam forming of each frequency point, and converting an image in the polar coordinate system into an image which accords with the visual habit of people in a rectangular coordinate system by sector conversion. By the FFT beam forming, the method can be implemented by an FFT algorithm in digital signal processing, and the requirement of system real-time imaging is met.

The invention provides IQ imbalance estimation and correction equipment, system and method. Quadrature demodulation of a received training sequence sent by a sending terminal is performed; a frequency offset estimate value of the training sequence is determined according to a reception signal in the demodulated training sequence; an IQ imbalance correction parameter of a receiving terminal is obtained through calculation according to the frequency offset estimate value; influences of carrier frequency offset are taken into consideration during estimation of the IQ imbalance correction parameter of the receiving terminal; an IQ imbalance correction parameter of the sending terminal is obtained according to the training sequence subjected to frequency offset compensation and the IQ imbalance correction by the receiving end; and influences of carrier frequency offset are also taken into consideration during estimation of the IQ imbalance correction parameter of the sending terminal. Therefore, IQ imbalance estimation and correction of the sending terminal is achieved. The IQ imbalance estimation and correction of the receiving terminal is achieved through a remote loopback mode, and the accuracy of IQ imbalance correction of a sending terminal and a receiving terminal of a system is improved.

The invention discloses a digital beam forming method of a broad band, which includes the steps of time division multiplexing quadrature sampling with intermediate frequency, quadrature demodulation, low pass filtering, interpolation delay, phase rotation and beam summation, etc. The beam forming method of the invention puts emphasis on that a single sample circuit is used for carrying out the time division multiplexing quadrature sampling with intermediate frequency on multipath bandpass signals; an FIR wave filter is used for completing the low pass filtering, the interpolation delay and the phase rotation which are matched with the signals at one time to realize the actual formation of delayed beams. As to the executive mode of wave filtering, a multi-channel wave filter with a cascade structure is disclosed. The wave filtering in the same path signal is completed in different filtering submodules by cascading while the different path signals share the same filtering module. The filtering output is completed with the sample selection, and the method of the invention is suitable for being realized in an ASIC or an FPGA and saves a great quantity of logic resources compared with the conventional wave filters.

The invention provides a self-closed calibration method for eliminating short-term burst interference signals, and aims to provide a method capable of effectively eliminating influences of short-term burst interference, ensuring accurate and reliable amplitude and phase test data and improving the calibration success rate of a phased array antenna in a short-term burst interference environment. The self-closed calibration method is implemented according to technical scheme that a calibration receiver performs down-conversion on signals returned by a tested antenna, sends generated intermediate-frequency signals to a calibration signal processing unit, calculates an amplitude value and a signal-to-noise ratio (SNR) of the tested signals according to in-phase component and quadrature component sampling values acquired by sampling and digital quadrature demodulation, compares the SNR with a preset judgment threshold SNRth to judge whether the signal-to-noise ratio of the tested signals meets requirements or not, and obtains amplitude and phase test data until required amplitude and phase tests of N states are completed; and then amplitude and phase distribution of the feed is calculated according to the obtained amplitude and phase test data, evaluation is performed by applying a calibration result, and whether a convergence requirement is met or not is judged.

A microwave photonics based signal receiving device includes a signal generation module, a first Mach-Zehnder modulator, a dispersion module, a second Mach-Zehnder modulator, and a signal conversion module. The signal receiving device simplifies a structure of the signal receiving device by adopting quadrature demodulation. The signal receiving device demodulates a high-order modulation signal and flexibly adjusts a microwave carrier frequency.

An input device is configured to detect force being applied to an input region of the device by an input object, in addition to the position of the input object using touch sensing methods. Aspects include driving a force sensing electrode of the input device using an anti-guarding voltage alternating with a ground or guard voltage, while driving the touch sensing electrodes with a reference voltage, to obtain touch measurements, force measurements, interference measurements, double the force signal, and/o double the touch signal for differential touch and force detection. Aspects also include driving sensor electrodes using orthogonal signals and performing in-phase and quadrature demodulation of the received signal for simultaneous and independent touch and force measurements.

The invention provides a safety detection system and method for millimeter-wave real-time imaging. The safety detection system comprises a transmission device, a millimeter wave transceiver module, an antenna array, a switch array, a switch control unit, a quadrature demodulation and data acquisition module and an image display unit. By adopting an inverse synthetic aperture radar (ISAR) imaging principle, through the adoption of the safety detection system for millimeter-wave real-time imaging, real-time imaging is conducted when an object to be detected moves, the imaging speed is increased, the field of view is enlarged, security personnel can judge whether or not a detected person carries dangerous objects by observing a three-dimensional diagram of the body of the detected person, and therefore the inconvenience caused by back-forth movement of security equipment used by the security personal on the body of the detected person is eliminated.

An IQ imbalance correction method in a wireless communication device includes transmitting a plurality of pairs of RF training signals in installments by pairing RF training signals symmetric with respect to a center frequency on a frequency axis; setting a reception local frequency to change to a frequency that is suitable to receive, via an internal path, each of the plurality of pairs of RF training signals transmitted in installments, and suitable to convert the each of the plurality of pairs of RF training signals into IF training signals; and performing quadrature demodulation on the IF training signals, respectively, in a digital circuit area to generate BB training signals.

The present invention belongs to the radar imaging technology field, and especially relates to a terahertz frequency band aperture coding high-resolution middle and long distance staring imaging device and method. The imaging device comprises a terahertz transmission module 1, a transmission antenna 2, an electric control secondary reflector array 3, a paraboloid primary mirror 4, a receiving antenna 5, a terahertz receiving module 6, a memory 7 and a system control host 8. The terahertz transmission module is connected with the transmission antenna, and the electric control secondary reflector array is connected with a system control host; the paraboloid primary mirror is configured to perform reflection and alignment of the terahertz coding wave beam; the receiving antenna collects the scattering echo signals of the surface of a target; the terahertz receiving module is configured to perform low noise amplification, frequency mixing and quadrature demodulation processing of the scattering echo signals; and the system control host performs relation imaging processing of the echo signals and the reference signals to obtain a target reconstruction image. The terahertz frequency band aperture coding high-resolution middle and long distance staring imaging device and method obtain the high-resolution capability in the wave beam of the identical caliber traditional radar diffraction limit and are fast in mode switching.

A negative feedback amplifier for a transmitter, in which a vector corrector outputs the corrected signals, an adder adds the feedback signals of the in-phase component and the quadrature component to the in-phase component and the quadrature component of the output of the vector corrector, respectively, a modulator performs a quadrature modulation with respect to the in-phase component and the quadrature component of the outputs from the adder, a power amplifier amplifies the output of the modulator, a demodulator performs a quadrature demodulation to a part of the output of the power amplifier and outputs the feedback signals of the in-phase component and the quadrature component, and the vector corrector performs a correcting operation of canceling an error of at least one of the phases and the amplitudes of the in-phase component and the quadrature component occurring in the demodulator.

An input device is configured to detect force being applied to an input region of the device by an input object, in addition to the position of the input object using touch sensing methods. Aspects include driving a force sensing electrode of the input device using an anti-guarding voltage alternating with a ground or guard voltage, while driving the touch sensing electrodes with a reference voltage, to obtain touch measurements, force measurements, interference measurements, double the force signal, and/o double the touch signal for differential touch and force detection. Aspects also include driving sensor electrodes using orthogonal signals and performing in-phase and quadrature demodulation of the received signal for simultaneous and independent touch and force measurements.