60results about How to "Reduce cross-correlation" patented technology

A system comprises a plurality of acoustic transmitters, mounted inside the streamers, adapted to transmit broadband signals having low cross-correlation between the signals of different transmitters; a plurality of acoustic receivers, mounted inside the streamers, adapted to receive the signals from the transmitters; at least one processor adapted to cross-correlate the signals received at the receivers with copies of transmitter signals to determine identities of the transmitters of the received signals and to determine travel times of the received signals; and a main processor adapted to convert the travel times to distances between the identified transmitters and the receivers and to determine relative positions of the streamers from the distances.

An apparatus for writing and reading holograms, comprising a spatial light modulator (SLM) operable in phase mode, having a plurality of pixels for generating an object beam that overlaps with a reference beam; a holographic recording medium (HRM) in the path of the object beam; and a first lens element disposed in the path of the object beam between the SLM and the HRM; wherein the HRM is disposed at or near the Fourier transform plane of the first lens element.

In a method for the continuous real time tracking of the position of at least one mobile object in a defined multidimensional space, at least one mobile transmitter module is attached to at least one mobile object and the signals from the at least one module are received by a stationary receiving and signal processing network and then centrally processed. The signals emitted by each transmitter module are electromagnetic waves sent within a frequency band range using time division multiplexing techniques. Due to the fact that the frequency band is used as a single channel for the purpose of maximizing the accuracy with which a position is detected, and due also to the fact that the communication process between the transmitters and the receivers is based on the principle of pseudo-random time division multiplexing using burst transmissions of low cross correlation with non synchronized pseudo-random patterns, there is created a method for the continuous tracking of the position of one or more mobile objects at any time and in any place which is of very high positional resolution and has a temporal resolution of just a few milliseconds.

A method, device and system for determining a receiver location using weak signal satellite transmissions. The invention involves a sequence of exchanges between an aiding source and a receiver that serve to provide aiding information to the receiver so that the receiver's location may be determined in the presence of weak satellite transmissions. With the aiding information, the novel receiver detects, acquires and tracks weak satellite signals and computes position solutions from calculated pseudo ranges despite the inability to extract time synchronization date f, 'n the weak satellite signals. The invention includes as features, methods and apparatus for the calibration of a local oscillator, the cancellation of cross correlations, a Doppler location scheme, an ensemble averaging scheme, the calculation of almanac aiding from a table of orbit coefficients, absolute time determination, and a modified search engine.

Different carrier frequencies are chosen for plural transmitters of a transmitting device and signals are transmitted at frequency bands overlapping each other. In the receiving device weighting coefficients are provided in input-to-output paths of an interchannel interference canceller 21 so that the cross correlation between output signals from the interchannel interference canceller is minimized.

It is an object to provide a sequence allocating method that, while maintaining the number of Zadoff-Chu sequences to compose a sequence group, is configured to make it possible to reduce correlations between different sequential groups and between same sequential groups. This method comprises the steps of setting a standard sequence with a standard sequence length (Nb) and a standard sequence number (rb) in a step (ST101), setting a threshold values (Xth1(m)) and (Xth2(m)) in accordance with an RB number (m) in a step (ST103), setting a sequence length (N) corresponding to RB number (m) in a step (ST104), judging whether ¦r / N−rb / Nb¦=Xth1(m) is satisfied in a step (ST106), judging whether ¦r / N−rb / Nb¦=Xth2(m) is satisfied in a step (ST107), including Zadoff-Chu sequences with a sequence number (r) and a sequence length (N) in a sequence group (rb) in a step (ST108); if both judgments are positive, and allocating the sequence group (rb) to the same cell in a step (ST113).

An apparatus for writing and reading holograms, comprising a spatial light modulator (SLM) operable in phase mode, having a plurality of pixels for generating an object beam that overlaps with a reference beam; a holographic recording medium (HRM) in the path of the object beam; and a first lens element disposed in the path of the object beam between the SLM and the HRM; wherein the HRM is disposed at or near the Fourier transform plane of the first lens element.

The invention provides a method for generating MIMO (multiple-input and multiple-output) radar orthogonal polyphase code signals on the basis of genetic-tabu hybrid algorithm. The method includes: firstly, randomly generating an initial population; secondly, judging whether a stop criterion of genetic algorithm is satisfied or not; thirdly, calculating a fitness function; fourthly, selecting by proportional selection; fifthly, intersecting; sixthly, mutating by tabu search algorithm; seventhly, updating the population, and returning to the step 3 for continuing genetic algorithm with the new population. Transmission signals with fine self-correlation and cross-correlation can be designed, and polyphase code waveform designed by the method has fixed phase and is easy to generate and more suitable for practical application.

Disclosed are an apparatus and a method for generating a preamble signal for cell identification in an OFDM mobile communication system. The method includes the steps of generating a Walsh code symbol for a cell identification by combining Walsh codewords having a predetermined length and generating the preamble signal through multiplying the Walsh code symbol by a pseudo noise (PN) code having a length identical to a length of the Walsh code symbol.

The method is applicable to long-term evolution system. The idea of the invention is that combination of time division multiplex (TDM) and frequency division multiplex (FDM) is adopted in RACH design, and combinations of multiple code words are adopted for RACH precursor. Relative to individual FDM, TDM, and CDM (code division multiplexing), technical scheme of the invention can obtain larger number of access users, and reduce interference between multiple users, and multiple sectors, use less number of correlator, and lowers complexity of sequence design.

The present application provides a sequence-based signal processing method, communication device and communication system. The sequence used to transmit the signal satisfying the PUCCH is determined,the sequence is a sequence {fn}comprising 12 elements, fn refers to the elements in the sequence {fn}, and the determined sequence is a sequence satisfying a preset condition. Then, the 12 elements inthe sequence are respectively mapped to 12 sub-carriers to generate a first signal and transmit the first signal. With the sequence determined above, it is possible to maintain low cross-correlationbetween sequences while maintaining low PAPR and CM values when signals are transmitted using the PUCCH, thereby satisfying a communication application environment in which signals are transmitted using the PUCCH.

The invention relates to the field of processing of a sonar signal, and particularly relates to a multi-base sonar space-time channel multiplexing method. The method comprises the following steps of obtaining a space-time code signal modulated in a pseudo random way; distributing independent and mutually orthogonal space-time code groups for transmitting terminals of a multi-base system; encoding the transmitting address and transmitting time of each transmitting signal; copying the related detection on the received signal, and distinguishing whether the detection signal of the corresponding transmitting terminal is contained in the received signal; extracting a time code, and using the space-time signal code of the corresponding base to carry out maximum likelihood decoding; and obtaining the information of the transmitting address and the transmitting time of the detection signal, namely the space-time information. The method has the advantages that the correlation between code elements of the space-time code is reduced, the high-efficiency multiplexing of the multi-base sonar space-time channel is realized by the accurate evaluation of the space-time information of any received signal, the time of the multi-base sonar system is improved, and the utilization rate of frequency bands is improved.

A method that is sub-optimal, but easily implemented, for cross correlation mitigation of GPS signals. It involves adaptive modification of the locally generated code used to detect a weak signal so that the new code is orthogonal to the jamming signals currently being tracked. The method employs simple constraints to achieve the orthogonalisation rather than a direct orthogonalisation performed using matrix inversions.

It is an object to provide a sequence allocating method that, while maintaining the number of Zadoff-Chu sequences to compose a sequence group, is configured to make it possible to reduce correlations between different sequential groups. This method comprises the steps of setting a standard sequence with a standard sequence length (Nb) and a standard sequence number (rb) in a step (ST101), setting a threshold value (Xth(m)) in accordance with an RB number (m) in a step (ST103), setting a sequence length (N) corresponding to RB number (m) in a step (ST104), judging whether ]r / N-rb / Nb]<=Xth(m) is satisfied in a step (ST106), including a plurality of Zadoff-Chu sequences with a sequence number (r) and a sequence length (N) in a sequence group (rb) in a step (ST107) if the judgment is positive, and allocating the sequence group (rb) to the same cell in a step (ST112).

The present application provides a sequence-based signal processing method, communication device and communication system. The sequence used to transmit the signal satisfying the PUCCH is determined,The sequence is a sequence {fn}comprising 12 elements, fn refers to the elements in the sequence, and the determined sequence {fn} is a sequence satisfying a preset condition. Then, the 12 elements inthe sequence are respectively mapped to 12 sub-carriers to generate a first signal and transmit the first signal. With the sequence determined above, it is possible to maintain low cross-correlationbetween sequences while maintaining low PAPR and CM values when signals are transmitted using the PUCCH, thereby satisfying a communication application environment in which signals are transmitted using the PUCCH.

A method, device and system for determining a receiver location using weak signal satellite transmissions. The invention involves a sequence of exchanges between an aiding source and a receiver that serve to provide aiding information to the receiver so that the receiver's location may be determined in the presence of weak satellite transmissions. With the aiding information, the novel receiver detects, acquires and tracks weak satellite signals and computes position solutions from calculated pseudo ranges despite the inability to extract time synchronization date f, ′n the weak satellite signals. The invention includes as features, methods and apparatus for the calibration of a local oscillator, the cancellation of cross correlations, a Doppler location scheme, an ensemble averaging scheme, the calculation of almanac aiding from a table of orbit coefficients, absolute time determination, and a modified search engine.

The invention discloses a wavelet constant modulus blind equalization method in a MIMO (Multiple Input Multiple Output) system from the aspect of reducing?inter channel?and inter signal?correlation, so as to overcome defects that the traditional constant modulus blind equalization method in the MIMO system is weak in inter channel interference inhibition ability, slow in the convergence rate and large in steady-state errors. According to the method, singular value decomposition is used for reducing the correlation of channel output signals; an orthogonal wavelet base function is used for carrying out orthogonal wavelet transformation on MIMO channel output signals and autocorrelation of input signals of a blind equalizer is reduced; on the basis of fully considering the inter channel correlation, a cost function of MIMO system constant modulus blind equalization algorithm is redefined, and cross-correlation of output signals of the blind equalizer is reduced; and a variable step size function is used for controlling a blind equalization?weight vector?updating process, the convergence rate quickened, and the steady-state errors are reduced.

An audio signal is processed by transforming the signal into a frequency domain representation having a plurality of frequency subbands. A decorrelated signal is derived from the frequency domain representation using a phase rotation.

A method, device and system for determining a receiver location using weak signal satellite transmissions. The invention involves a sequence of exchanges between an aiding source and a receiver that serve to provide aiding information to the receiver so that the receiver's location may be determined in the presence of weak satellite transmissions. With the aiding information, the novel receiver detects, acquires and tracks weak satellite signals and computes position solutions from calculated pseudo ranges despite the inability to extract time synchronization date f, 'n the weak satellite signals. The invention includes as features, methods and apparatus for the calibration of a local oscillator, the cancellation of cross correlations, a Doppler location scheme, an ensemble averaging scheme, the calculation of almanac aiding from a table of orbit coefficients, absolute time determination, and a modified search engine.

The present invention provides a signal processing method and device based on a sequence. A sequence used for meeting PUCCH (Physical uplink control channel) sending signals is determined, the sequence is a sequence {fn} comprising N elements, the fn shows the elements in the sequence {fn}, the determined sequence {fn} is a sequence meeting a preset condition, the N elements in the sequence {fn} are respectively mapped on N carriers to generate first signals for transmission. The determined sequence is determined to maintain the low cross correlation between the sequences when the PUCCH sending signals are used and maintain a low PAPR (Peak to Average Power Ratio) value and a CM (Cubic Metric) value so as to meet the communication application environment of employing the PUCCH sending signals.

The invention provides a sequence-based signal processing method, signal processing device and computer readable storage medium. The method comprises the following steps: determining a sequence used for meeting a reference signal or a control channel sending signal; wherein the sequence is a sequence [fn] comprising N elements, the fn refers to elements in the sequence [fn], the determined sequence [fn] is a sequence meeting a preset condition, and then the N elements in the sequence[fn] are respectively mapped to N subcarriers to generate a first signal and send the first signal. By utilizing the determined sequence, low cross-correlation between the sequences can be kept, and a reference signal or a control channel can keep a lower PAPR value and a lower CM value, so that a communication application environment for transmitting a signal by utilizing the reference signal or the control channel is met, especially when / 2 <-> is transmitted; And when the BPSK modulates the data signal or carries out frequency shaping filtering on the reference signal or the control channel.

The invention provides a secondary synchronization sequence generating method, a detection method, a base station and user equipment. The secondary synchronization sequence generating method comprisesthe following steps: generating a scramble sequence of a main synchronization signal; generating an m sequence according to predetermined primitive polynomials, wherein the predetermined primitive polynomials include at least two primitive polynomials, and an m sequence pair consisting of m sequences generated by any two primitive polynomials is an m sequence preferable pair; and generating the secondary synchronization sequence according to the scramble sequence of the main synchronization signal and the m sequence. The user equipment receives a synchronization signal transmitted by the basestation, and performs descrambling and relevant detection on the signal in order to realize time frequency synchronization and obtain cell identification information. According to the scheme of the invention, the secondary synchronization sequence with relatively low cross-correlation can be generated, so that misjudgment on sequence detection in a synchronous detection process is avoided, and the detection accuracy is increased.

The invention discloses a nonlinear frequency modulation pulse train waveform design method based on frequency spectrum modulation agility, which can generate different NLFM waveforms by using a stationary phase principle based on a frequency spectrum structure of an LFM signal, and can effectively suppress the problems of range ambiguity, interference and clutter folding. The method comprises the following steps: determining a pulse width T, a bandwidth B, a pulse repetition interval Tr and a pulse number N of a waveform to be designed, generating linear frequency modulation signals with the same bandwidth and pulse width, and obtaining a power spectral density function L(f) of the linear frequency modulation signals; reserving the out-of-band shape of the L(f), modulating the amplitude of the in-band power spectral density function of the L(f) through a random sinusoidal modulation method, and designing an NLFM waveform power spectral density function NL (f); calculating a group delay function Tg(f) of the NLFM signal based on the NL(f); and determining the instantaneous frequency f(t) of the signal according to the group delay function Tg(f): conducting integration on the instantaneous frequency f(t) to obtain a phase function of the signal, and obtaining a time domain expression of the designed NLFM waveform according to the phase function.

The invention discloses an LFM pulse train signal waveform design method based on pulse width agility. The method comprises the steps: setting different pulse widths for different pulses in an LFM pulse train with the same bandwidth, so that each pulse signal has different modulation rates, and the cross correlation between the pulses is reduced so as to effectively improve the range gating characteristic and the folding clutter resistance of the generated LFM pulse train signal and achieve the purpose of suppressing range ambiguity and resisting folding clutter.

The invention provides a sequence-based signal processing method, a communication device and a communication system. The method comprises the steps: determining a sequence which meets the applicationrequirements of a PUCCH for transmitting a signal, wherein the sequence is a sequence {fn} which comprises 12 elements, and fn is the elements in the {fn}, and the determined sequence {fn} is a sequence meeting a preset condition; mapping 12 elements in the sequence {fn} to 12 subcarriers, generating a first signal, and transmitting the first signal. Through the above determined sequence, the method can maintain the low correlation between sequences when the PUCCH is used for transmitting a signal, maintains the lower PAPR value and CM value, and meets the requirements of a communication application environment where the PUCCH is used for transmitting the signal.

The present invention provides a sequence-based signal processing method and device, and the method comprises the steps: determining a sequence that meets the requirement of a PUCCH for transmitting asignal, wherein the sequence is a sequence {fn} of N elements, and fn is an element in the sequence {fn}, and the determined sequence {fn} is a sequence meeting a preset condition; mapping N elementsin the sequence {fn} onto N subcarriers, generating a first signal and transmitting the first signal. Through the sequence determined above, the method can maintain low cross-correlation between sequences while transmitting signals using the PUCCH, maintains a lower PAPR value and CM value, thereby meeting the requirement of a communication application environment in which signals are transmittedusing the PUCCH.

The invention provides a sequence-based signal processing method and device. The method comprises the following steps: determining a sequence used for sending signals by using a PUCCH (Physical UplinkControl Channel), wherein the sequence is a sequence {fn} including N elements, fn means elements in the sequence {fn}, and the determined sequence is a sequence that satisfies a preset condition; and then respectively mapping N elements in the sequence {fn} to N sub-carriers, and generating a first signal and sending the first signal. By means of the determined sequence, the low cross-correlation between sequences can be kept when the PUCCH is used for sending the signals, and meanwhile, a lower PAPR value and a lower CM value are kept, so that the communication application environment utilizing the PUCCH to send the signals is met.

The invention provides a signal processing method and device. The method comprises the step that in frequency domain resources of a comb tooth structure, reference signals mapped on the frequency domain resources of different comb teeth can be generated by different sequences. That is to say, the reference signals on different frequency domain resources can be generated by adopting different sequences, so that the performance of the reference signals transmitted on the frequency domain resources of the whole comb tooth structure is improved.

Electronic devices for communicating in wireless ad-hoc networks and multiple access systems (such as mobile radio telephone communications systems) are disclosed. For example, a disclosed transmitter can transmit data to a first receiver in an ad-hoc wireless network (or multiple access system) over a first channel and can, further, transmit data to a second receiver in the ad-hoc wireless network (or multiple access system) over a second channel that is separate from the first channel, where the first and second channels are determined by the respective receivers which will receive the first and second transmitted data. Accordingly, communications between transmitters and different receivers in the ad-hoc wireless network (or multiple access system) can be carried on simultaneously. Related receivers as well as methods, computer program products, and systems for communicating are also disclosed.

The invention discloses an airborne equipment electromagnetic compatibility grading method based on an unascertained measurement theory. The method comprises the following steps of S1, measuring the grading evaluation indexes of the electromagnetic compatibility of airborne equipment, and building a grading evaluation index set; S2, establishing a measurement function of grading evaluation indexes by applying an uncertain measurement theory; S3, solving a single index evaluation matrix of the electromagnetic compatibility of the airborne equipment; S4, solving a grading evaluation index weight of each electromagnetic compatibility by using an information entropy method; S5, solving the comprehensive attribute measure of each airborne device; S6, solving quantitative grading or classification of the electromagnetic compatibility of the airborne equipment on the airplane; and S7, obtaining the electromagnetic compatibility design priority and design weight of the airborne equipment. According to the method, the cross correlation of evaluation indexes is low, the evaluation indexes can be measured and examined, the evaluation indexes can serve as a priority strategy for system-level electromagnetic compatibility index distribution, and a theoretical basis is provided for quantitative design of electromagnetic compatibility of the whole aircraft system.