122 results about "Out of band interference" patented technology

Embodiments of the invention may provide for reducing interference in the front-end of a communications receiver. The cancellation circuitry may be utilized in conjunction with a preliminary rejection filter for improved rejection of out-of-band interference from other radio services or circuitry. The cancellation circuit may be placed in parallel with the preliminary rejection filter and may enhance suppression at the interference frequency by matching the gain and phase of the preliminary rejection filter prior to subtracting the matched signal from the preliminary rejection filter output. The cancellation circuit need not necessary know beforehand the characteristics of the preliminary rejection filter, the interference source, or the coupling mechanism, as it may adapt to unknown or varying interferers by adapting the matching gain and phase values based on the output of the preliminary rejection filter at tap points occurring both before and after application of the cancellation signal.

A radiofrequency (RF) receiver circuit and method offer one or more performance improvements, such as an increased input compression point through better out-of-band interference suppression. In one example, an RF receiver circuit includes a low-noise amplifier (LNA) circuit and a mixer. The mixer output signal serves as negative feedback to the LNA circuit for improved compression point performance at interferer frequencies in or out of band with respect to a frequency of interest. Compression point performance is further improved for interferer signal components away from the frequency of interest by including at least one frequency-dependent circuit in the LNA circuit that is configured to reduce amplifier gain for such frequencies. The frequency-dependent circuit(s) may be tunable for different frequencies of interest. Additional improvements may be obtained by including a broadband input matching circuit and/or by including active mixer loads to increase the voltage conversion gain of the RF receiver circuit.

Embodiments of the invention may provide for reducing interference in the front-end of a communications receiver. The cancellation circuitry may be utilized in conjunction with a preliminary rejection filter for improved rejection of out-of-band interference from other radio services or circuitry. The cancellation circuit may be placed in parallel with the preliminary rejection filter and may enhance suppression at the interference frequency by matching the gain and phase of the preliminary rejection filter prior to subtracting the matched signal from the preliminary rejection filter output. The cancellation circuit need not necessary know beforehand the characteristics of the preliminary rejection filter, the interference source, or the coupling mechanism, as it may adapt to unknown or varying interferers by adapting the matching gain and phase values based on the output of the preliminary rejection filter at tap points occurring both before and after application of the cancellation signal.

The sending end buffers the waveform signals processed by subband filter banks; cutting off the streaking signals at the beginning and end of the buffer waveform to get the truncated signals; making the looping stack from beginning to end of the truncated signals to get the transmission signals of time domain looping from beginning to end.

The invention discloses a device and a method for inhibiting coexistence interference of WiMAX and WiFi. When a user receives radio-frequency signals of a wireless network by the device, a WiMAX filter module filters WiFi radio-frequency signals received by a WiMAX antenna, WiMAX radio-frequency signals are converted into the WiFi radio-frequency signals, and a WiFi filter module filters out-of-band interfering signals of the WiFi radio-frequency signals which is then sent to the user by a WiFi antenna; when the user sends the radio-frequency signals to the wireless network by the device, theWiFi filter module filters the WiMAX radio-frequency signals received by the WiFi antenna, the WiFi radio-frequency signals are converted into the WiMAX radio-frequency signals, and the WiMAX filter module filters the out-of-band interfering signals of the WiMAX radio-frequency signals which is then sent to the wireless network by the WiMAX antenna, thus reducing the interference between WiMAX and WiFi, increasing the data transmission rate and avoiding waste of frequency spectrum resources.

The invention provides a high-frequency-selectivity radio-frequency front end suitable for nano-scale. The front end comprises a high-frequency input matching network, a lower-noise transconductor, a load network and a passive frequency mixer, wherein the passive frequency mixer is arranged on an output node of the input matching network or the low-noise transconductor or the load network; impedance conversion is adopted by the input matching network and the load network to realize high Q values and high frequency selectivity for filtering out-of-band interference; a radio-frequency signal is filtered by using the high-Q-value input matching network, and is then amplified by using the transconductor and the load of the high-Q-value load network which is subjected impedance conversion; a high-frequency signal is converted to a low-frequency signal by performing down-conversion with the passive frequency mixer for processing with an analog or digital baseband. The radio-frequency front end has the advantages of low power consumption, high image rejection ratio, high out-of-band linearity, strong gain configurability, no need of off-chip SAW (Surface Acoustic Wave) filter and the like, and is suitable for application to a future multifunctional integrated radio-frequency chip.

The invention provides a radar communication integrated signal generation method and device. The method includes the following steps: performing three-stage design on a communication symbol sequence to be processed, and performing continuous phase modulation (CPM) on the acquired three-stage communication symbol sequence to generate a CPM signal, and loading the CPM signal to a chirp signal to generate a radar communication integrated signal. Thereby, the three-stage design of the radar communication integrated signal can be realized, and thus the radar communication integrated signal can be limited to a bandwidth range of the chirp signal, the out-of-band attenuation and out-of-band interference of a power amplifier and the noise effects can be avoided, the radar communication integrationrequirements can be met, the original working distance and detection tracking performance of radars can be maintained, and the requirements of high-speed data transmission can also be achieved.

A noise abatement method and system for impulse noise in an RF receiver where the RF analog signal is converted to a digital signal prior to being connected to a demodulator. Two filters are used to detect impulse noise signals even under out-of-band interferer conditions, and prevent the impulse noise from reaching the input to the demodulator. A first of the two filters detects impulse noise using signals lower than the frequency bandwidth of the desired signal, and a second of the two filters detects impulse noise using signals higher the frequency bandwidth of the desired signal. A mean magnitude of the signal is detected over a predetermined time T and is used to select which filter to use for noise abatement.

The invention relates to the field of electric power telecommunication used for supporting smart power grids, in particular to a digital front end system used for power line carrier communication and an implementation method of the digital front end system. The digital front end system comprises a transmitter and a receiver, wherein the transmitter and the receiver carry out communication in sequence. The transmitter comprises an inversion Fourier transformation module, a windowing module I, an interpolation filter, a frequency mixer I and a digital-analog converter, wherein the inversion Fourier transformation module, the windowing module I, the interpolation filter, the frequency mixer I and the digital-analog converter carry out communication in sequence. The receiver comprises an analog-digital converter, a frequency mixer II, an interpolation filter, a windowing module II and a Fourier transformation module, wherein the analog-digital converter, the frequency mixer II, the interpolation filter, the windowing module II and the Fourier transformation module carry out communication in sequence. The implementation method of the digital front end system comprises the following steps: 1, a modulation symbol is input to the transmitter and converted into an analog signal; 2, the analog signal is input to the receiver and converted into the modulation symbol. The digital front end system used for the power line carrier communication and the implementation method of the digital front end system combine a digital front end in the form of an equivalent complex number base band with a Nyquist windowing method, and have the advantages of supporting frequency band selection and bandwidth configuration, suppressing out-of-band interference, reducing sending signal out-of-band energy, and suppressing in-band narrow-band interference.

The invention discloses a radio frequency front-end frequency selection circuit and a signal receiving method thereof. The circuit comprises: an antenna used for coupling and receiving a radio frequency signal; a first multipath switch used for selecting the radio frequency signal to a microstrip filter of a corresponding frequency band; the microstrip filter used for filtering an out-of-band interference signal; a low noise amplifier used for amplifying the useful radio frequency signal; and a filter group used for filtering the amplified signal; a second multipath switch used for switching the radio frequency signal obtained by the filter group to a subsequent link of a receiver to be processed. The method comprises the steps that: the radio frequency signal is coupled to a radio frequency link by the antenna, the first multipath switch switches the radio frequency signal to the microstrip filter of the corresponding frequency band, the microstrip filter filters the out-of-band interference signal and amplifies and filters the useful signal for the second time, and finally the signal is switched to the subsequent link of the receiver to be processed. The radio frequency front-end frequency selection circuit disclosed by the invention has the advantages of miniaturization, integration and strong expansibility.

A wireless receiver (110) for UWB or other format, receives a useful signal in a particular band of frequencies in site spite of interference components inside and outside the particular band of frequencies. An interference detector (130, 535, 555) detects the in band interference component in a first range of frequencies to include the particular band of frequencies. The same receiver circuitry (120, 300, 310, 505) is adapted to receive a second range of frequencies to include frequencies adjacent to the particular band, to detect the out of band interference component. The position of a second interfering signal in the second range is used to detect artifacts caused by spectral folding so that the required frequency of a band reject filter can be found.

The invention relates to the field of communication, and provides a signal transmission and reception method capable of performing combined suppressing on a peak-to-average power ratio and out-of-band power based on a mixed carrier system. An object of the invention is to achieve combined suppressing on the peak-to-average power ratio and the out-of-band interference based on the mixed carrier system. The key points of the invention are that: 1. in a 4-WFRFT based mixed carrier wireless communication system, a time- and frequency-domain combined technique, in which time-domain windowing and frequency-domain shaping are combined, is used to simultaneously suppress the peak-to-average power ratio and the out-of-band power; 2. a windowing mode which does not influence the error rate is used for the time domain; and 3. in a mixed carrier mechanism, a method of analyzing the peak-to-average power ratio and the out-of-band power in a time- and frequency-domain combined manner is used. The signal transmission and reception method provided by the invention is applicable to transmission terminals and reception terminals of the 4-WFRFT based mixed carrier wireless communication system.

A small S-band passive phased array antenna with high radiation efficiency comprises a power supply module, a 4W power amplifier module, a filter module, a beam control module, a phase shifter module and an antenna array, wherein the power supply module supplies power for the 4W power amplifier module, the beam control module and the phase shifter module; the 4W power amplifier module is used for amplifying a radio-frequency signal; the filter module is used for inhibiting out-of-band interference and noise; the beam control module is responsible for calculating the beam pointing of the phased array antenna according to the GPS position and posture information of a user satellite; the phase shifter module is used for controlling the phase of the output signal; the antenna array transmits and outputs the signal. The phased array antenna, disclosed by the invention, has a wide scanning range, controllable beam, high gain, low power consumption and small size, and is capable of controlling the antenna beam pointing through the beam control module.

The invention discloses a device capable of adaptively cancelling receiving out-of-band interference in a wireless transceiver system. The function of the device is that signals coupled from a radio frequency transceiving channel are filtered by a wave trap to remove transmitting signals, and then the signals are amplified and split by a power splitter, one path of signals enter a cancellation circuit after being delayed, and the other path of receiving signals generated by a receiving signal generation unit are cancelled with original receiving signals in the cancellation circuit after amplitude modulation/phase modulation; a data processing unit adjusts an amplitude modulation phase modulator according to the sizes of the signals detected by a receiving signal detection circuit until thereceiving signals are smaller than a preset value; and then the data processing unit adjusts the amplitude and phase of cancellation interference signals according to the sizes of the receiving interference signals that are detected, and feeds back the adjusted interference signals to a receiving main channel to cancel the interference signals in the main channel. Thereby, the problem of the interference to the receiving main channel can be solved; and according to the scheme of the application, the receiving interference signals can be adaptively cancelled according to the changes of the receiving interference signals, and the shortcoming that a traditional filter cannot adaptively filter out the interference with the changes of the interference signals can be overcome.

The invention discloses a method for generating multi-input multi-output over-the-horizon (MIMO-OTH) radar waveforms based on digital signal processor (DSP) sequences, belonging to the technical field of MIMO-OTH radar and aiming to generate emission signals for an MIMO-OTH radar system. According to the technical problems that an MIMO-OTH radar has a narrower working frequency range and strong out-of-band interference, the method is characterized in that emission waveforms are constructed based on the DPS sequence and the waveform of each emission antenna is generated by conducting weighing summation on the same group of DPS sequences by adopting a group of different weights, therefore, waveforms of different emission antennas can be either orthorhombic or correlated with each other. In a circumstance that the total energy emitted by radar and other working parameters are constant, the detection probability of the MIMO-OTH radar system can be improved in a way of optimizing preset waveform weight parameters; and by adopting the method disclosed by the invention, the MIMO-OTH radar system achieves a good detection performance.

The invention belongs to the technical field of the modulation carrier system, and discloses an iterative detection method of joint channel estimation in a FBMC system. The method comprises the following steps: eliminating interference in a first-order neighbor domain by using auxiliary pilot to accomplish a channel initial estimation value; estimating the interference out of the first-order neighbor domain by uniting the iterative detection, and feeding back the interference to modify the channel initial estimation value, thereby improving the estimation precision and acquiring an accurate detection result. Compared with the traditional orthogonal frequency division multiplexing technology, and the multi-carrier technology of a filter bank has higher spectrum use ratio, lower out-of-bandinterference and better synchronization robustness without using the cyclic prefix. Since the FBMC/OQAM system satisfies the orthogonality at the real-number field, and inherent imaginary part interference is existent in the complex field, and the great challenge is brought to the channel estimation. The simulated analysis result shows that the algorithm provided by the invention is fast in convergence rate and high in estimation precision.

The invention discloses a high-dynamic high-sensitivity broadband receiver with self-adaptive interference suppression. The broadband receiver includes an FPGA digital processing module, a main channel receiving module and at least one interference scanning receiving module; the FPGA digital processing module controls the interference scanning receiving module to perform rapid scanning and obtain a single or a plurality of interference frequency points having the maximum influence on receiving performance, and tunes a suppression frequency band of the main channel receiving module so as to enable the main channel receiving module to maximally suppress dynamically varying out-of-band interference; the main channel receiving module tunes a passband and poles according to a control signal sent by the FPGA digital processing module; and the interference scanning receiving module is used for performing scanning in a full frequency band, locking the strongest interference, and providing interference frequency points and amplitude for the FPGA digital processing module. The high-dynamic high-sensitivity broadband receiver with self-adaptive interference suppression can dynamically track interference and accurately suppress interference, thereby greatly improving receiver performance under dynamic interference.

An automatic gain control loop disposed in a receiver is adapted to compensate for varying levels of out of band interference sources by adaptively controlling the gain distribution throughout the receive signal path. One or more intermediate received signal strength indicator (RSSI) detectors are used to determine a corresponding intermediate signal level. The output of each RSSI detector is coupled to an associated comparator that compares the intermediate RSSI value against a corresponding threshold. The take over point (TOP) for gain stages is adjusted based in part on the comparator output values. The TOP for each of a plurality of gain stages may be adjusted in discrete steps or continuously.

The invention provides a method and device for reducing out-of-band interference of cognitive radio. The method comprises the steps that NMSK coded modulation is conducted on an OFDM baseband signal and a modulated OFDM-NMSK single side band signal is obtained; according to the modulated OFDM-NMSK single side band signal and the requirement for interference elimination of each cognitive frequency band, subcarrier bandwidths needing to be closed and corresponding to each windowing coefficient are determined in advance; an interference elimination closing data list at least comprising the interference elimination requirement of each cognitive band, each windowing coefficient and the corresponding subcarrier bandwidths needing to be closed is established ; when a user need to exit out of the occupied cognitive frequency band, the interference elimination closing data list is inquired according to the interference elimination requirement of the cognitive frequency band and the corresponding windowing coefficient is selected; according to the selected windowing coefficient, a corresponding number of subcarriers are closed. According to the method and device for reducing the out-of-band interference of the cognitive radio, the out-of-band interference of the cognitive radio is effectively reduced and meanwhile the system performance is improved.