50 results about "Hadamard code" patented technology

A system and methods are provided for imaging an object, based on activating an array of discrete X-ray sources in a prescribed temporal pattern so as to illuminate the object with a beam varying in spatial orientation, and detecting X-rays of the beam after interaction with the object and generating a detector signal. An image of the object may then be constructed on the basis of the time variation of the detector signal. The discrete X-ray sources may be moved during the course of inspection, moreover, the prescribed temporal pattern may constitute a Hadamard code. The discrete sources may be carbon nanotube x-ray sources.

A system and methods are provided for imaging an object, based on activating an array of discrete X-ray sources in a prescribed temporal pattern so as to illuminate the object with a beam varying in spatial orientation, and detecting X-rays of the beam after interaction with the object and generating a detector signal. An image of the object may then be constructed on the basis of the time variation of the detector signal. The discrete X-ray sources may be moved during the course of inspection, moreover, the prescribed temporal pattern may constitute a Hadamard code. The discrete sources may be carbon nanotube x-ray sources.

In one embodiment, a Walsh-Hadamard decoder can have a hardware efficient Fast Hadamard Transform (“FHT”) engine. In one embodiment, the FHT engine can include an input to receive an input sequence to be decoded into a Walsh-Hadamard codeword. The FHT engine can further include a controller to correlate the received input sequence with a plurality of Walsh-Hadamard codewords using two add / subtract modules. In one embodiment, the two add / subtract modules operate in parallel.

A coded mass spectrometer incorporates a spatial or temporal code to reduce the resolution / sensitivity dichotomy inherent in mass spectrometry. The code is used to code one or more portions of a mass spectrometer. Coding patterns, such as Hadamard codes, Walsh codes, and perfect code sequences can be used. The coding can be spatial, for example, by using an aperture mask and / or temporal, for example, by coded injection of ions for analysis.

An encoder includes an outer repetition encoder, an interleaver for permuting encoding from said outer repetition encoder; and an inner encoder for encoding information from the interleaver to provide a repeat zigzag-Hadamard code. In an exemplary embodiment, a common bit of a zigzag-Hadamard segment of encoding from said inner encoder is a repetition of a last parity bit of a previous zigzag-Hadamard segment of encoding from said inner encoder and said common bit is punctured.

The invention relates to a hadamard transform imaging spectrometer based on a bridge type grating light modulator, and the spectrometer provided by the invention can be applied to a linear array detector or single point detector. The hadamard transform imaging spectrometer comprises a receiving optical system, a chromatic dispersion element, an imaging mirror, a bridge type grating light modulator array, a focusing mirror and a detector, wherein the radiation information of a target is imaged on the chromatic dispersion element in lines by the receiving optical system according to different time sequences; after being split by the chromatic dispersion element, the radiation information is imaged on the programmable bridge type grating light modulator array by the imaging mirror; the bridge type grating light modulator array is programmed and driven according to a hadamard coding template, thereby allowing lights with different wavelengths to pass through in a manner of specific combination; the lights are focused on the detector by the focusing mirror; and finally, the space dimensional information and spectrum dimensional information of the target are acquired by performing the hadamard inverse transformation. The hadamard transform imaging spectrometer has the advantages of small volume, light weight, low cost, high speed and high signal to noise ratio. The hadamard transform imaging spectrometer can be widely applied to the fields of aerial remote sensing, industry, agriculture, biomedicine, matter analysis and classification, universal and astronomic surveillance, environment and disaster monitoring, atmospheric detection, searching and tracking for military targets, and the like.

A method for selecting a signal to noise ratio for a communications code includes obtaining extrinsic information transfer (EXIT) information for a repeat-zigzag Hadamard (RZH) code responsive to a Hadamard order and a signal to noise ratio, determining code parameters for an irregular repeat zigzag Hadamard (IRZH) code for a corresponding code rate in response to the obtained EXIT values, and repeating the step of obtaining the EXIT information for a different signal to noise ratio if the corresponding code rate is other than a selected rate. The corresponding code rate is related to a bit error rate. In a preferred embodiment, the step of obtaining EXIT information includes one of obtaining an EXIT curve for repeat-zigzag Hadamard code by Monte Carlo simulation using serial decoding or obtaining an EXIT function for parallel decoding of the repeat-zigzag Hadamard code by using equations.

An encoder includes an outer repetition encoder, an interleaver for permuting encoding from said outer repetition encoder; and an inner encoder for encoding information from the interleaver to provide a repeat zigzag-Hadamard code. In an exemplary embodiment, a common bit of a zigzag-Hadamard segment of encoding from said inner encoder is a repetition of a last parity bit of a previous zigzag-Hadamard segment of encoding from said inner encoder and said common bit is punctured.

The invention provides a cascading Hadamard code-aided iterative carrier synchronization scheme under an environment with an extremely low signal to noise ratio (SNR). By using the scheme, even under the environment with an extremely low SNR, accurate synchronization and correct decoding can be realized, and more importantly, the synchronization range is enlarged. In the invention, a transmittingend and a receiving end are utilized. The transmitting end is used for coding low density parity check (LDPC)-Hadamard cascading codes and adding pilot frequency. At the receiving end, different fromthe conventional simple pilot frequency unicode-aided carrier method, the method provided by the invention comprises the following steps: firstly, carrying out Hadamard code related search by using the orthogonality of Hadamard codes to pre-estimate a wide range of frequency offset and compensate the frequency offset, thus the frequency offset is greatly compensated in the process; secondly, extracting the pilot frequency of the compensated information for coarsely synchronizing; carrying out fine synchronization by utilizing the ideas of decoding iteration and maximum likelihood; and finally, carrying out decoding judgment.

A memory circuit, such as an embedded DRAM array, stores information as groups of bits or data using information coding in storage and retrieval data, instead of each bit being stored separately. Write data words can be mapped to storage format words that are stored and defined by a Hadamard matrix. The storage format word is stored as charge levels in an addressable memory location. For retrieving stored data, charge levels are read from the storage cells and interpreted to a valid storage format word. Hadamard code maximal likelihood decoding can be used to derive a read data word corresponding to a previously written write data word. The write data word is then output as the result of a read of the selected addressable location, or a portion thereof. The mapping can be two or more Hadamard matrix mappings concatenated for each of a plurality of storage format words.

The invention is directed toward a variable spectral phase encoder. The variable spectral phase encoder includes a plurality of switches and at least one encoder. The encoder is coupled between a first switch and second switch among the plurality of switches. The first switch selectively routes an optical signal to some combination of fixed encoders such that their collective product applies one of the Hadamard sequences to the optical signal.

A computer-implemented method of processing a query vector and a data vector), comprising: generating a set of masks and a first set of multiple signatures and a second set of multiple signatures by applying the set of masks to the query vector and the data vector, respectively, and generating candidate pairs, of a first signature and a second signature, by identifying matches of a first signature and a second signature. The set of masks comprises a configuration of the elements that is a Hadamard code; a permutation of a Hadamard code; or a code that deviates from a Hadamard code or a permutation of a Hadamard code in less than 40% of its elements.

The invention relates to a super low bit rate code auxiliary carrier wave synchronization method for deep space communication. According to the method, combination design for a pilot frequency and a super low bit rate code parameter can be carried out at a sending end, coarse synchronization is carried out at a reception end by employing the pilot frequency, the super low bit rate code is further combined to facilitate carrier waves to realize precise synchronization, and thereby large-scale carrier wave synchronization under the super low signal-to-noise ratio is realized. The method is advantaged in that the method works under the super low signal-to-noise ratio, and the carrier wave synchronization scope is large. According to the method, construction of a system, a low bit rate and a short code length LDPC-Hadamard code is mainly illustrated on the basis of the pilot frequency and coding combined auxiliary synchronization algorithm, combination and synchronization of the pilot frequency, the low bit rate and the short code length LDPC-Hadamard code are mainly analyzed, the detailed flow chart is provided, moreover, performance of the method is analyzed.

A method for generating and transmitting a cell ID code for cell recognition is disclosed. The first 16-bit cell ID codes for 2-bit FBI field are generated from 16-bit Hadamard codes, and the first and ninth bits of the Hadamard codes are punctured, to thereby generate the second 14-bit cell ID code for the 2-bit FBI field. The puncturing is performed by a network or a terminal.

A memory circuit, such as an embedded DRAM array, stores information as groups of bits or data using information coding in storage and retrieval data, instead of each bit being stored separately. Write data words can be mapped to storage format words that are stored and defined by a Hadamard matrix. The storage format word is stored as charge levels in an addressable memory location. For retrieving stored data, charge levels are read from the storage cells and interpreted to a valid storage format word. Hadamard code maximal likelihood decoding can be used to derive a read data word corresponding to a previously written write data word. The write data word is then output as the result of a read of the selected addressable location, or a portion thereof. The mapping can be two or more Hadamard matrix mappings concatenated for each of a plurality of storage format words.

A method and apparatus are disclosed for modulating a communication signal in a code division multiple access (CDMA) environment using orthogonal N by N Hadamard spread spectrum codes Orthogonal spreading codes are used that have lengths that are not a power-of 2 to provide additional channel variability for various multimedia applications and increase the flexibility of the number of channels / bandwidth relationship. The Hadamard codes are multiples of 4 (4n) and demonstrate a good cross-correlation property, making them very useful in the flexible design of code division multiple access (CDMA) systems. A transmitter encodes each of to N data streams (N not being a power of 2), to be transmitted using a 4n codeword, Ni. The received signal is passed through a filter matched to the characteristics of the appropriate codeword, Ni, and PN spreading sequence.