108results about How to "Increase processing gain" patented technology

A method for transmitting digital beamformed signals in a transmit array antenna apparatus utilizing a single transceiver with one power amplifier, one up-frequency converter and one digital-to-analog converter for said array transmit antenna apparatus comprising the steps of: generating a first set of direct-sequence spread spectrum codes; generating a plurality of weights, each weight being a beamforming amplitude and phase or delay for each element; generating a direct-sequence spread spectrum multiplexed signal containing such weights while using one of such first-set codes per element; converting such an multiplexed signal to a convenient radio frequency; amplifying and transmitting such a multiplexed radio frequency signal to the elements; generating a second set of direct-sequence spread spectrum codes; extracting a radio frequency signal with direction-bearing weight information at each element while using a subset of codes from the second set; generating a third set of direct-sequence spread spectrum codes at each element; transmitting a signal with array gain beamformed towards a specific direction while using a transmit array apparatus composed of spaced elements, such a transmit beamformed signal being a radio frequency signal, a direct-sequence spread spectrum radio frequency signal containing a subset of codes from the third set, or a sequence of radio frequency pulses that have short duration and high power.

An energy efficient MAC protocol for a sensor network that extends the battery life of remotely located wireless nodes by employing MAC operations involving transmission of a wake-up signal with more processing gain, dynamic adjustment of a transmission rate of synchronization messages for fast time synchronization and an energy efficient neighboring node discovery technique.

A system and method for determining the position of an aircraft. An aircraft signal is received by a first antenna and a second antenna, the first antenna being at a known baseline distance from the second antenna. A processor is used to calculate the time difference of arrival range between the second antenna and the aircraft using a common time reference signal. The position of the aircraft is determined by a position determinator based upon the baseline distance between the first and second antennas, the range between the first antenna and the aircraft, and the time difference of arrival range between the second antenna and the aircraft.

A multiple integration hypothesis C / A code acquisition system resolves bit boundaries using parallel correlators providing magnitude hypotheses during acquisition to reduce losses over the 20 ms integration period to improve the performance and sensitivity of C / A code receivers to achieve low C / No performance using inexpensive, imprecise oscillators and long noncoherent dwell periods, well suited for in-building, multipath, and foliage attenuated GPS signaling applicable to E911 communications with several dB of additional improvement in receiver sensitivity due to the ability to detect bit synchronization during acquisition.

The present invention discloses a radio altimeter based on PN code distance measurement which comprises of emitting module, receiving module and digital signal processing module, wherein, clock input signal of emitting module as intrinsic signal is transferred to modulator, after the intrinsic signal is modulated by modulating code input by digital signal processing module, variable RF signal is output as effect of power control signal, and radiated after amplified by power amplifier, the clock signal of receiving module as receiving intrinsic signal is mixed with receiving intrinsic, outputs intermediate frequency and transmitted to digital signal processing module after amplified of intermediate frequency amplifier as action of AGC control signal to produce PN code, clock, power control signal and AGC control signal, and capturing and tracking receiving signal to output measurement data. The present invention has merits of large height measurement range and high measurement precision, and is useful for measuring height of the flying load to ground.

The present invention provides a remote communication device (i.e., radio frequency identification (RFID) tag) and system for communicating between one or more RFID tags and a reader using a frequency modulation method to encode binary data.

A microelectromechanical device includes a semi-flexible proof-mass comprising a primary part, a secondary part and a stiff spring suspending the primary part and the secondary part. The spring causes the parts to move as a single entity when the device is in its normal range. A first stopper structure stops the primary part. The proof-mass is configured to deform through deflection of the spring, when the device is subjected to a shock having a force that is beyond the normal operation range. While the shock causes motion of the proof-mass in one direction along an axis of movement, the spring is configured to cause a restoring force causing the secondary part of the proof-mass to be driven into a restoring motion in a direction opposite to motion along an axis caused by the shock. Momentum of the secondary part causes the primary part to dislodge from the first stopper structure.

The invention discloses an incoherent spread spectrum digital transceiver instantaneous frequency measurement and demodulation method. The instantaneous frequency measurement and demodulation method is low in algorithm realization complexity and is multistation interference resistant. The method is realized through the following technical scheme that an incoherent reception algorithm module captures Doppler frequencies and code phases, detects sample data of an analog-to-digital converter through synchronization headers and finishes synchronization header correlation detection; an instantaneous frequency measurement module and a digital downconversion module eliminate Doppler through near-real-time ms magnitude Doppler frequency difference measurement and compensation, decimation filteringand matching filtering are carried out through an IDF decimation filter, sign bits of I and Q data are directly obtained, the data is changed into single bits for follow-up processing, incoherent demodulation and RS decoding are finished, and user data is output; and a spread spectrum transmitting algorithm module carries out framing, RS coding, differential coding and direct sequence spread spectrum processing on the user data, then carries out sign mapping and modulation on the user data, sends the user data to a DAC for digital-to-analogue conversion, and the DAC filters the user data through a double end to single end transformer and a second filter and outputs instantaneous frequency measurement and demodulation signals.

Sodar systems and methods for acoustically sounding air are disclosed in which chirps longer than 300 ms-and preferably with durations of tens of seconds-are used along with matched filter and / or Fourier processing methods to derive phase signals indicative of air characteristics in range. A listen-while-transmit strategy is preferred, the direct signal being removed by subtracting the phase signals from two or more receivers located near the transmitter so as to be in the same noise environment. The resultant differential signals can be related to cross-range wind with range distance. In one example, apparatus (100) is employed comprising a reflector dish (102) over which one central loudspeaker (110) and four microphones (112, 114, 130 and 132) are mounted, the microphones preferably being located on cardinal compass points and having their axes (124, 126) slightly angled with respect to the vertical transmission axis (122).

A method and system for determining a geolocation of an object includes collecting a positioning signal including a predetermined message data segment. A time of arrival of the predetermined message data segment may be determined in the positioning signal. Information based on the time of arrival may be provided for determination of a geolocation of an object. The time of arrival of the predetermined message data segment may be determined based on a time search for the predetermined message data segment in the positioning signal.

The invention discloses an M-element parallel combination Chirp spread spectrum air sound wave communication method, and the method comprises steps: signal transmitting and signal receiving. The method comprises the steps: generating a Chirp sequence set which is formed by the construction of Chirp signals; enabling to-be-transmitted digital information to be modulated by an M-element parallel combination Chirp spread spectrum modulation unit into a modulation signal; inserting a synchronous signal and a time protection interval before the modulation signal, so as to form a transmission signal; carrying out the time synchronization of the received signal, obtaining the starting time of a sound signal, and recovering original digital information of a digital signal part through an M-element parallel combination Chirp spread spectrum demodulation unit. The method provided by the invention can effectively improve the utilization rate of conventional Chirp spread-spectrum frequency bands, neutralizes a multi-path effect and a Doppler effect in an air sound channel, is low in calculation complexity, is large in processing gain, is strong in resistance to the Doppler effect, and is convenient to use in an intelligent terminal with audio receiving and transmitting equipment.

A method and system for determining a geolocation of an object includes collecting a positioning signal including a predetermined message data segment. A time of arrival of the predetermined message data segment may be determined in the positioning signal. Information based on the time of arrival may be provided for determination of a geolocation of an object. The time of arrival of the predetermined message data segment may be determined based on a time search for the predetermined message data segment in the positioning signal.

A system and method communicates and generates a Coded Orthogonal Frequency Division Multiplexed (COFDM) communications signal as a plurality of subcarriers. Selected subcarriers are turned ON and OFF while also frequency hopping and spreading the selected ON subcarriers over the frequency domain based on a fixed or variable sample rate to reduce average power for enhanced Low Probability of Interception / Low Probability of Detection (LPI / LPD) and also allow for more transmit power within a spectral mask.

A GPS receiver for integrating a GPS signal separately in a series of “A” type and “B” type time segments, the “A” segments alternating with the “B” time segments; combining the squares of the magnitudes of “A” time segment integrations corresponding to code phases for forming “A” type combined magnitudes; combining the squares of the magnitudes of the “B” time segment integrations corresponding to code phases for forming “B” type combined magnitudes; and determining an acquisition code phase of the signal from the strongest of the “A” or “B” combined magnitudes. The “A” time segments and the “B” time segments are one-half the period of the data bits of the signal, thereby ensuring that either the “A” time segments or the “B” time segments avoid the nullifying effect of data bit inversions.

The invention provides a method for capturing a GNSS-BOS (Global Navigation Satellite System-Binary Offset Carrier) modulation signal under the condition of low signal-noise ratio aiming at a BOC modulation signal. The method comprises the following steps of: firstly, stripping a carrier of an intermediate-frequency input signal; secondly, changing values of each phase in a Local_PRN (Pseudo Random Number) signal and a Local_BOC signal modulated by the BOC from 1 to 0; and thirdly, acquiring the superposed intermediate-frequency input signal and the like. According to the method disclosed by the invention, the multi-peak characteristic of an autocorrelation function of the BOC modulation signal can be eliminated; the false detection and leak detection generated by the multi-peak characteristic when a GNSS receiver captures the BOC modulation signal can be avoided; the computational load for improving the correlation operation and coherent accumulation method is greatly reduced; the processing time of the GNSS receiver to the input signal is shortened; and the real-time property of the receiver is enhanced.

Provided are modulation and demodulation methods and apparatuses using a frequency selective baseband. The frequency modulation method includes: generating a plurality of subgroups by dividing 2N (N is a real number) spread codes used for frequency spreading into 2M (M<N, M is a real number) spread codes; selecting P(P is a real number) subgroups among the generated subgroups; acquiring P spread codes by inputting M data bits to each of the p subgroups so as for 1 spread code to be selected among the 2M spread codes of each subgroup; and selecting dominant value among the acquired P spread codes to generate transmitting data including the dominant value. Accordingly, it is possible to increase a processing gain of the entire system, to increase a transmission data rate, and to reduce power consumption of the system.

The invention discloses a complex moving target ISAR imaging method based on a quasi-time-frequency bilinear coherence algorithm, and the method comprises the following steps: obtaining the echo dataof a target, and carrying out the distance compression and translation compensation of an echo signal; extracting data from the signal along the distance direction, and calculating an improved cubic phase function MCPF of an extraction result; performing Radon-CPF-Fourier transform on the MCPF, and obtaining a three-dimensional data matrix in a Doppler center-polar radius-polar angle domain; and projecting the three-dimensional data matrix to a Doppler central axis along a polar radius and a polar angle, and generating a final high-resolution inverse synthetic aperture radar (ISAR) image by recombining all distance-Doppler centers. According to the method, the cross term interference suppression of a cubic phase function can be realized under the condition of no time-frequency resolution loss, the signal gain is improved, the calculation performance is improved, and a clear maneuvering target ISAR image is obtained.

The invention discloses GPS weak signal fast capture implement method. It includes the following steps: storing the received GPS signal data in the memory; sending to phase detection module to detect data segment position with phase jumping; dividing the data into phase jumping before and after; separately putting on the grouped data G1 and G2; processing coherent integration; sending the result to the compare module; sending the maximum to gain judgment module to judge whether the gain satisfies the capture demand or not; if it is not, sending it to the phase detect module to process the next data. The invention combines the phase jumping detection with the coherent integration to judge code phase jumping position caused by navigation message which can fully utilize received satellite data to realize coherent integration for long time, solve the problem of low capture sensitivity caused by integration loss and low gain.

Methods and systems are provided for accessing GPS signals in faded environments. Means are provided for predicting the nonlinear phase induced by the receiver's own clock, when there is at least one GPS satellite link strong enough to calculate a phase profile. In an embodiment, GPS signals are accessed in faded environments by increasing the sensitivity of a GPS receiver by increasing the processing gain of received GPS signals through increased integration time. Matching a near-baseband signal requires removing a nonlinear part of the phase which may arise from several sources, including: the phase drift of the GPS satellite's atomic clock, the phase drift due to the motion of the GPS receiver, the phase drift due to the motion of the GPS satellite, and the phase drift due to the GPS receiver's clock.

The invention relates to a uniformed linear array beam forming method based on time reversal, belongs to the time reversal target directional technology of shallow sea multi-path channels, and relates to the field of time reversal and array signal processing. The uniformed linear array beam forming method based on the time reversal resolves the problem of uniform linear target direction under a strong noise interruption background. Due to the fact that the time reversal is capable of conducting cophasal stacking of multi-path signals based on transmission channel matching, energy for receiving signals is reinforced, consequently system gain of signal detection is improved, and therefore the time reversal has strong advantages of signal detection under a strong noise circumference, particularly under the background of shallow sea multi-path channels. Meanwhile, the application of the time reversal in the target direction field is perfected by self-adaptation beam forming of the uniform linear array, beam control can be conducted conveniently by the acquirement of an optimal weighting factor of each array element by using the uniform linear array under the target direction background, spatial filtering is conducted to a self-adaptation beam forming directional diagram, and thus purpose of precise orientation is achieved.

The invention discloses a sonar target enhancement method of a new image operator, which solves the problem of target trajectory enhancement of a passive sonar azimuth history map. The invention provides a new image detection operator, which detects and processes the multi-frame data after beamforming, thereby realizing the reduction of background noise, the suppression of lateral lines and the extraction of target trajectory edges. Adaptive segmented equalization of the detected row data increases the local data contrast, increases the contrast between the target and background, obtains a larger processing gain, significantly enhances the target, and the azimuth history map is clear. The invention does not need to set any parameters, has good compatibility, small calculation amount, simple programming realization and the like, and can be used for the processing of the dynamic history diagram and the static two-dimensional image, and has wide application range.

The invention relates to a quasi-real-time cable-free network seismograph system based on an ultra wide band wireless module. The system is provided with a display and control central station and multiple groups of acquisition nodes. The display and control central station is provided with a host computer, an ultra wide band wireless module A, an epicenter trigger, an intelligent battery, and a voltage stabilization module A. Each group of acquisition node is provided with a single-chip microcomputer module, an ultra wide band wireless module B, a signal conditioning and data acquisition module, an intelligent battery, and a voltage stabilization module B. All the acquisition nodes are arranged into 14 groups, each group assigns an aggregation node, other acquisition nodes in the group send data to the aggregation node in order, and all the aggregation nodes then send the data to the display and control central station. After being started up, the system can self-organize wireless Internet of Things, and the ultra wide band wireless modules A, B work at 3.1-10.6GHz. The system is small in size, light in weight, low in cost, low in battery power consumption and high in interference resistance. Relative positions of the nodes can be resolved automatically, an error range of the positioning precision is from -1.0cm to 1.0cm, and the synchronization precision is 1[mu]s. The system is suitable for being popularized and applied in the field of geological exploration.

The invention discloses a GNSS-R delay mapping software receiver. The GNSS-R delay mapping software receiver comprises a direct mapping channel, a code generating module, a carrier generating module, a BAP processing module and relevant modules. Direct mapping digital intermediate frequency signals are captured and tracked through the direct mapping channel, and local codes are generated through the code generating module. Local carriers are generated by the carrier generating module to carry out carrier stripping on reflected signals. The reflected signals after carrier stripping are divided into L blocks with the length of one ms through the BAP processing module, the L blocks are overlaid and averaged, white noise suppression and non-specular reflection point signal component suppression are achieved, coherent processing is carried out on the signals processed by a BAP and the local codes through the relevant modules, and one-dimensional correlation power is output. The GNSS-R delay mapping software receiver has the advantages of having the functions of white noise suppression and non-specular reflection point signal component suppression, being small in computation complexity and the like.

A spread spectrum communications system using long, scalable PN sequences to achieve variable communication rates using a low-complexity and scalable matched filter architecture to provide a large processing gain, robust recovery of multiple devices in long reach, high ambient-noise environments.

Provided are a digital communication system using frequency selective baseband and a method thereof. A transmitter of the digital communication system, includes: a preamble / header transmission processing unit for spreading a preamble for frame synchronization and a header including data information; a data transmission processing unit for spreading data by using spread codes having dominant frequency in a desired frequency band, i.e., frequency selective spread codes; and a multiplexer for multiplexing the spreaded preamble and the spreaded header from the preamble / header transmission processing unit and the frequency selective spreaded data from the data transmission processing unit and transmitting the multiplexed signal in digital.

The invention discloses a three-dimensional sonar imaging system based on a graph processor and a three-dimensional image method thereof. The three-dimensional sonar imaging system comprises a signal down-sampling module and the like which are sequentially connected. The signal down-sampling module is used for transferring an underwater acoustic signal received by an underwater acoustic sensor from high frequency to low frequency and converting the underwater acoustic signal into a digital signal convenient to process by a computer. A high-speed buffer module is used for storing multi-channel sampling data received from the signal down-sampling module. A parallel beam forming module based on an image processor reads multi-channel echo data from the high-speed buffer module. A wideband pulse compression module based on the image processor processes frequency domain signals output by the parallel beam forming module in different spatial angle directions. A three-dimensional display module receives output information of a beam forming module based on the image processor and output information of the wideband pulse compression module based on the image processor. The system and the method have the advantages of being low in cost, high in performance, strong in expansibility and the like.