Abstract: A method for manufacturing a piston with a re-molten reinforced combustion chamber throat is provided. The manufacturing steps includes: a) piston rough machining: machining allowances of the combustion chamber throat and the combustion chamber bottom are 1-3 mm; b) piston washing and degreasing treatment; c) coating or spraying a surfactant on the combustion chamber throat and the combustion chamber bottom that need to be re-molten, wherein the surfactant formula comprises the components TiO2, SiO2, CuCl2 and MnCl2 that are mixed in percentage: 1-30% of TiO2, 1-30% of SiO2, 1-40% of CuCl2 and 1-50% of MnCl2; after the four components are uniformly mixed, a suspension is prepared by using acetone as a solvent a mass ratio of 1:(3-8); d) re-melting the piston by using an A-TIG welding method; and f) after re-melting, processing the piston into a finished product.

Abstract: A method for manufacturing a piston with a re-molten reinforced combustion chamber throat is provided. The manufacturing steps includes: a) piston rough machining: machining allowances of the combustion chamber throat and the combustion chamber bottom are 1-3 mm; b) piston washing and degreasing treatment; c) coating or spraying a surfactant on the combustion chamber throat and the combustion chamber bottom that need to be re-molten, wherein the surfactant formula comprises the components TiO2, SiO2, CuCl2 and MnCl2 that are mixed in percentage: 1-30% of TiO2, 1-30% of SiO2, 1-40% of CuCl2 and 1-50% of MnCl2; after the four components are uniformly mixed, a suspension is prepared by using acetone as a solvent a mass ratio of 1: (3-8); d) re-melting the piston by using an A-TIG welding method; and f) after re-melting, processing the piston into a finished product.

Abstract: This invention concerns the estimation of signal to noise ratio (SNR) at a communications receiver; it may be applicable to a wide range of receivers but is particularly suited for Orthogonal Frequency Division Multiplexing (OFDM) receivers. In particular the invention is a method, a receiver and software for performing the method. The signal to noise ratio (SNR) in the received signals is estimated by directly estimating the power ratio, in the received signal, between the part of the frequency spectrum of the received signal that contains only noise, and the part of the spectrum that contains both signal and noise; and averaging this value over a time interval.

Abstract: This invention concerns soft-decision demapping of Quadrature Amplitude Modulation (QAM) signals to enable soft-decision channel decoding in a communications system. In a first aspect the invention is a method for performing the soft-decision demapping of Quadrature Amplitude Modulation (QAM) signals to enable soft-decision channel decoding in a communications system. The method comprises the steps of Extracting baseband signals from both I-and-Q channels. Sampling the baseband signals to extract a stream of complex numbers. Converting the stream of complex numbers to frequency domain vectors with components for each subcarrier frequency. Approximating bit log-likelihood ratios for each symbol directly from the real and imaginary parts of the corresponding frequency vector, without equalization by the estimated channel. And, soft-decoding of the channel codes using the approximated log-likelihood ratios.

Abstract: In one aspect, the method of synchronizing a communications device in a wireless communications network comprises receiving a beacon signal at a first frequency; and receiving a data signal at a second frequency, the beacon signal being used to synchronize reception of the data signal. In another aspect, the method comprises transmitting a beacon signal at a first frequency; and transmitting a data signal at a second frequency, the beacon signal being useable to synchronize reception of the data signal. The first frequency is substantially less than the second frequency such that the beacon signal experiences substantially different frequency-dependent propagation effects to the data signal.

Abstract: A Symbol vector for RF transmission after multiplexing onto a subset of a set of subcarriers using OFDM is transformed to the time domain. A first time domain cancellation vector is generated from a basis vector that has the same dimensionality as the symbol vector. In the frequency domain the basis vector has a substantially zero value in each of a first subset of sub-carriers of the symbol vector and in the time domain the difference between a first element of the basis vector having the highest value and a second element of the basis vector having the next highest value is maximized. The first cancellation vector is subtracted from the symbol vector to produce modified symbol vector having reduced Peak-to-Average Power Ratio (PAPR). A second cancellation vector is generated using the modified symbol vector and is used to produce a second modified symbol vector having reduced PAPR.

Abstract: This invention concerns the estimation of signal to noise ratio (SNR) at a communications receiver; it may be applicable to a wide range of receivers but is particularly suited for Orthogonal Frequency Division Multiplexing (OFDM) receivers. In particular the invention is a method, a receiver and software for performing the method. The signal to noise ratio (SNR) in the received signals is estimated by directly estimating the power ratio, in the received signal, between the part of the frequency spectrum of the received signal that contains only noise, and the part of the spectrum that contains both signal and noise; and averaging this value over a time interval.

Abstract: A method for improving noise performance in a Radio Frequency (RF) transmitter that makes use of Orthogonal Frequency Division Multiplexing (OFDM). The method • comprising the steps of: receiving a stream of digital data symbols in the form of symbol vectors, for RF transmission after multiplexing onto a subset of a set of sub-carriers according to OFDM and transforming each received symbol vector to the time domain; generating a first time domain cancellation vector from a basis vector that has the same dimensionality as the symbol vectors. In the frequency domain the basis vector has substantially zero value in each of the first subset of sub-carriers of the symbol vector and in the time domain the difference between a first element of the basis vector having the highest value and a second element of the basis vector having the next highest value is maximised.

Abstract: This invention concerns soft-decision demapping of Quadrature Amplitude Modulation (QAM) signals to enable soft-decision channel decoding in a communications system. In a first aspect the invention is a method for performing the soft-decision demapping of Quadrature Amplitude Modulation (QAM) signals to enable soft-decision channel decoding in a communications system. The method comprises the steps of: Extracting baseband signals from both I-and-Q channels. Sampling the baseband signals to extract a stream of complex numbers. Converting the stream of complex numbers to frequency domain vectors with components for each subcarrier frequency. Approximating bit log-likelihood ratios for each symbol directly from the real and imaginary parts of the corresponding frequency vector, without equalisation by the estimated channel. And, soft-decoding of the channel codes using the approximated log-likelihood ratios.

Abstract: In one aspect, the method of synchronising a communications device in a wireless communications network comprises receiving a beacon signal at a first frequency; and receiving a data signal at a second frequency, the beacon signal being used to synchronise reception of the data signal. In another aspect, the method comprises transmitting a beacon signal at a first frequency and transmitting a data signal at a second frequency, the beacon signal being useable to synchronise reception of the data signal. The first frequency is substantially less than the second frequency such that the beacon signal experiences substantially different frequency-dependent propagation effects to the data signal.

Abstract: A method includes storing at least one user datum received from a user in a secure storage portion of a memory within a mobile communication device. Authentication information is received into the mobile communication device. The at least one user datum is transmitted from the mobile communication device to a recipient in response to entry of the authentication information, while preventing the user of the mobile communication device from reading the at least one user datum.

Abstract: In one embodiment, a demapper uses two hybrid-QPSK constellations to demap pairs of equalized data symbols recovered from 16-QAM, DCM OFDM symbols, wherein the equalized data symbols in a pair correspond to the same four-bit group. A first hybrid-QPSK constellation is generated by combining the real components of both 16-QAM mapping constellations onto one coordinate plane. The demapper generates a first set of two decision variables by combining the real components of each equalized data symbol in a pair to correspond to the first hybrid-QPSK coordinate plane. A log-likelihood ratio is then calculated for both decision variables in the set to determine likelihood estimates for the first and second bits of the four-bit group. This process is repeated for the imaginary components of each corresponding pair of equalized data symbols to generate likelihood estimates for the third and fourth bits of the four-bit group.

Abstract: In one embodiment, a demapper uses two hybrid-QPSK constellations to demap pairs of equalized data symbols recovered from 16-QAM, DCM OFDM symbols, wherein the equalized data symbols in a pair correspond to the same four-bit group. A first hybrid-QPSK constellation is generated by combining the real components of both 16-QAM mapping constellations onto one coordinate plane. The demapper generates a first set of two decision variables by combining the real components of each equalized data symbol in a pair to correspond to the first hybrid-QPSK coordinate plane. A log-likelihood ratio is then calculated for both decision variables in the set to determine likelihood estimates for the first and second bits of the four-bit group. This process is repeated for the imaginary components of each corresponding pair of equalized data symbols to generate likelihood estimates for the third and fourth bits of the four-bit group.

Abstract: A method includes storing at least one user datum received from a user in a secure storage portion of a memory within a mobile communication device. Authentication information is received into the mobile communication device. The at least one user datum is transmitted from the mobile communication device to a recipient in response to entry of the authentication information, while preventing the user of the mobile communication device from reading the at least one user datum.

Abstract: In one embodiment, a demapper uses two hybrid-QPSK constellations to demap pairs of equalized data symbols recovered from 16-QAM, DCM OFDM symbols, wherein the equalized data symbols in a pair correspond to the same four-bit group. A first hybrid-QPSK constellation is generated by combining the real components of both 16-QAM mapping constellations onto one coordinate plane. The demapper generates a first set of two decision variables by combining the real components of each equalized data symbol in a pair to correspond to the first hybrid-QPSK coordinate plane. A log-likelihood ratio is then calculated for both decision variables in the set to determine likelihood estimates for the first and second bits of the four-bit group. This process is repeated for the imaginary components of each corresponding pair of equalized data symbols to generate likelihood estimates for the third and fourth bits of the four-bit group.

Abstract: In one embodiment, an OFDM transmitter generates sets of frequency-domain data symbols from a stream of digital data. For each set of frequency-domain data symbols generated, the transmitter generates a corresponding set of frequency-domain pilot symbols. Each corresponding set of data symbols and pilot symbols are then multiplexed onto a set of frequency tones, such that, at least one tone is occupied by both a data symbol and a pilot symbol. For each tone having both a pilot symbol and data symbol, the pilot symbol and data symbol are added together to form an overlaid data and pilot (ODP) tone. Each set of tones having at least one ODP tone is then transmitted to an inverse fast Fourier transform (IFFT) processor that transforms each set of tones into an ODP OFDM symbol. Each ODP OFDM symbol is then prepared for transmission using digital-to-analog conversion, cyclic prefix insertion, and RF modulation.

Abstract: A filter bank (10) and receiver including the filter bank (10) that is designed for processing a baseband signal of a received continuous phase modulated signal S(t) with an integer modulation index. The filter bank (10) has outputs for providing a plurality of decision variable values (d1,d2,d3,d4) each representing a likelihood value of a symbol, from a group of predefined symbols that are likely to be present in the continuous phase modulated signal S(t). The filter bank 10 has filter units (12,14,16,18) each having an impulse response determined by a complex main pulse containing a majority of signal energy of one of the predefined symbols that is likely to be in the continuous phase modulated signal S(t).

Abstract: A device (100) and method (700) for creating a spread spectrum signal by providing a complementary code spreading signal (740) having an auto-correlation function of zero, for any non-zero offset, at integer multiples of a selected time interval. The method includes modulating (750) a data stream with the complementary code spreading signal to provide the spread spectrum signal.

Abstract: A method, system and electronic device (100) for providing a partially encrypted data packet in a spread spectrum signal. The device has a spread spectrum signal encoder (140) having a data input, an output and a plurality of modulators (202,204,206) with inputs respectively coupled to outputs of a direct sequence generator (110), a scrambling sequence generator (120) and a carrier generator (125). There is also an output unit (150) coupled to an output of the spread spectrum signal encoder (140). In use when a data packet comprising a payload field of bits and non-payload field of bits is received by the spread spectrum signal encoder (140), the modulators (202,204,206) modulate the data packet to provide the partially encrypted data packet with the payload being a spread spectrum signal encrypted by a scrambling sequence from the scrambling sequence generator (120) and the non-payload field comprises a spread spectrum signal free of encryption by said scrambling sequence.

Abstract: A filter bank (10) and receiver including the filter bank (10) that is designed for processing a baseband signal of a received continuous phase modulated signal S(t) with an integer modulation index. The filter bank (10) has outputs for providing a plurality of decision variable values (d1,d2,d3,d4) each representing a likelihood value of a symbol, from a group of predefined symbols that are likely to be present in the continuous phase modulated signal S(t). The filter bank 10 has filter units (12,14,16,18) each having an impulse response determined by a complex main pulse containing a majority of signal energy of one of the predefined symbols that is likely to be in the continuous phase modulated signal S(t).