164 results about "Differential modulation" patented technology

This invention modulates data onto a radio channel in such a way that the deleterious effects of the channel are reduced. This is accomplished in three steps: first, the information signal is modulated using a phase-differential modulation scheme. Second, the modulated signal is spread in both time and frequency by passing it through a dispersive filter, transmitting it through the channel, and removing the spreading using a dispersive filter in the receiver with the opposite characteristics of the filter in the transmitter. The third step, after demodulation, is to pass the signal through a low-pass filter to gather up the signal energy which has been dispersed by the channel. All three of these steps can be implemented with simple functional blocks, making this system very inexpensive to implement. Also included are two methods for enhancing the data throughput of the basic system, making it more bandwidth efficient.

Differential modulation schemes encode a data channel within host signal or noisy environment in a manner that is robust, flexible to achieve perceptual quality constraints, and provides improved data capacity. Differential arrangements enable a decoder to suppress host signal or other background signal interference when detecting, synchronizing and extracting an encoded data channel. They also enable the incorporation of implicit or explicit synchronization components, which are either formed from the data signal or are complementary to it.

A method of diagnosing cancer by identifying differential modulation of each gene (relative to the expression of the same genes in a normal population) in a combination of genes selected from two groups of genes.

Gene expression portfolios and kits for employing the method are further aspects of the invention.

The invention relates to receivers and methods for receiving multi-carrier differentially modulated signals utilizing iterative decision-directed differential detection. The receiver includes a decision feedback loop including a channel estimator for estimating inter-symbol channel variations, and a differential equalizer for correcting channel-induced errors in a differentially detected signal based on the estimated inter-symbol channel variations.

A preferably CMOS-implementable system measures distance and/or brightness by illuminating a target with emitted optical energy having a modulated periodic waveform whose high frequency component may be idealized as S.sub.1=cos(.omega..multidot.t). A fraction of the emitted optical energy is reflected by a target and detected with at least one in a plurality of semiconductor photodetectors. Photodetector quantum efficiency is modulated to process detected signals to yield data proportional to the distance z separating the target and photodetector. Detection includes measuring phase change between the emitted optical energy and the reflected fraction thereof. Quantum efficiency can be modulated with fixed or variable phase methods and may be enhanced using enhanced photocharge collection, differential modulation, and spatial and temporal multiplexing. System power requirements may be reduced with inductors that resonate with photodetector capacitance at the operating frequency. The system includes on-chip photodetectors, associated electronics, and processing.

An efficient system and method for modulation and demodulation to achieve a high data rate using Bit-Interleaved Coded Modulation and OFDM uses either a coherent or a non-coherent transmission scheme using differential modulation. In order to maintain a high data rate impervious to sudden phase changes, a communication system uses an efficient constellation having multiple rings with different sizes and modulation/demodulation schemes utilizing this constellation. In power line communications, the channel gain information is obtained easily at a receiver (100) while the phase information is not. Thus, the communication system uses an absolute magnitude and differential phase coding for modulation and demodulation of the signals.

An optical data storage and retrieval system uses a flying head. The flying head is supported on a moving media having information stored in a plurality of stored data locations thereon. Information is stored in each of the plurality of media locations as physical structures capable of modulating the polarization state of incident light into one of two output polarization states. The flying head includes an optical processing assembly which directs an incident light beam having a source polarization state onto the moving media, accessing successive data locations. A reflected light beam having the source polarization state of the incident light beam modulated by a respective polarization modifying data location into one of the output polarization states is received by the flying head. The optical processing assembly optically transforms the modulated output polarization state of the reflected light beam into two return light beams having differentially modulated intensity related to the output polarization state of the reflected light beam. The two intensity modulated return light beams are optically coupled to a distal differential detector which outputs digital data representing the stored data information for the subject data location. A preferred embodiment includes optical fibers for coupling the incident and return light beams between the detector and the flying head. The optical assembly of a preferred embodiment includes an optical plate having pre-shaped and dimensioned recesses for automatically locating and aligning multiple optical components comprising the assembly. The flying head may also include a servo-controlled micro machined mirror for directing the incident and reflected light beams to and from the media.

The present invention makes it possible to transmit data while reducing the influence of fading caused on a transmission path. When communication data is transmitted by using a plurality of subcarriers arranged with a predetermined bandwidth, a data block consisting of a plurality of subcarriers arranged in rows in a time axis direction is used as a data unit. By implementing both a differential modulation process based on each phase difference in the frequency axis direction between a plurality of subcarriers and a differential modulation process based on each phase difference in the time axis direction between a plurality of subcarriers, a transmission signal with symbol data superposed on each phase difference between a plurality of subcarriers is generated and output.

The invention discloses an encoder which comprises an encoding and modulating module, an interweaving module, a serial-parallel transformation module and a differential encoding module. After an input information sequence line is modulated and encoded by the encoding and modulating module, weighting and differential encoding processing is respectively carried out for multipath parallel signals through the differential encoding module, and an encoding signal is obtained and output. The invention also discloses a decoder and a decoding method. In the technical scheme disclosed by the invention, through adopting a simpler and highly efficient data processing method, the complexity of decoding and demodulation algorithms of a differential encoding technology and a differential modulation technology is reduced, the processing delay is reduced, and the speed of data processing is improved.

A relatively high-speed, high-efficiency CMOS two branch driver core that may operate under relatively low supply voltage may include thin oxide CMOS transistors configured to generate rail-to-rail output swings larger than twice a supply voltage and without exceeding safe operating area limits. Each of the two branches may include two stacked CMOS inverter pairs configured to drive a respective load capacitance coupled between respective CMOS inverter outputs, in phase opposition to the other branch. A pre-driver circuit input with a differential modulating signal may output two synchronous differential voltage drive signals of a swing of half of the supply voltage and DC-shifted by half of the supply voltage with respect to each other and that may be applied to the respective CMOS inverter inputs of the two branches.

The invention discloses a differential encoding space-time-frequency modulation method, and belongs to the technical field of wireless communication. The method comprises that: a mobile terminal of a communication system performs space-time encoding on an information bit sequence required to be transmitted to generate a unitary matrix code word sequence; the unitary matrix code word sequence is subjected to differential modulation to generate a matrix sequence to be transmitted; symbols in the matrix sequence to be transmitted are respectively mapped to a space domain, a time domain and a frequency domain so as to acquire a group of space-time-frequency three-dimensional signals; a plurality of groups of transmission signals are acquired through OFDM modulation, and each group of transmission signals is transmitted through a transmitter antenna; and the OFDM modulation and differential demodulation are directly carried out a receiving end, and required information is acquired. Through differential space-time-frequency block code mapping or differential space-time-frequency cyclic code mapping, the encoding and the differential modulation are respectively carried out at different dimensionalities, so that a requirement of a channel on relevance of the time domain and the frequency domain is reduced, and a requirement of reliable signal transmission in high-speed mobile environment in a wideband communication system can be met.

The invention discloses a frequency domain joint estimation method of integer frequency offset and fine symbol synchronization. The method comprises the following steps of: carrying out circular shifting and differential modulation on a frequency domain training sequence of a transmitting end; then carrying out cross-correlation on the frequency domain training sequence processed by the circular shifting and the differential modulation and a frequency domain training sequence processed through differential modulation of a receiving end; obtaining a corresponding circular shifting bit through detecting the peak value of a cross-correlation result so as to obtain an integer multiple frequency offset estimation value; and meanwhile, solving for a fine symbol synchronization result through taking a phase angle of the cross-correlation result. By utilizing the invention, the integer multiple frequency offset estimation and the fine symbol synchronization can be carried out simultaneously, the problem that the integer multiple frequency offset estimation and the fine symbol synchronization are not accurate and mutually influence in the traditional time frequency joint estimation method is solved, and the accuracy of the integer multiple frequency offset estimation and the fine symbol synchronization is improved.

A method of determining a training signal so as to facilitate acquisition of symbol sync, frequency offset estimation, and channel estimation in an orthogonal frequency division multiplexing (OFDM) system, and an apparatus and method for receiving a baseband OFDM signal using the training signal are provided. The method of determining the training signal, which is transmitted from an OFDM transmitter to an OFDM receiver using N subcarriers in order to allow the OFDM receiver to perform symbol synchronization, frequency synchronization, and channel estimation in the OFDM system, includes determining a first training symbol by setting odd-numbered subcarriers to 0 in a frequency domain, obtaining even-numbered subcarriers using M-ary phase-shift keying (M-PSK), and performing differential modulation so that a change in the phase difference between remote two subcarriers is constant; and determining a second training symbol by setting even-numbered subcarriers to 0 in the frequency domain, obtaining odd-numbered subcarriers using M-PSK, and performing differential modulation so that a change in the phase difference between remote two subcarriers is constant. By performing all of symbol timing recovery, frequency offset estimation, and channel estimation using the training signal determined as described above, time taken for frequency offset estimation can be reduced, hardware complexity can be decreased, a frequency acquisition range can be expanded up to ½ of the entire bandwidth, and influence of a multi-path channel can be counterbalanced.

The invention aims to provide a remote underwater sound communication method and belongs to the technical field of underwater sound communication. The method is based on demodulation and decoding combined iterative detection of differential encoding. A transmitter resists multi-path interference by using spread spectrum communication, the problem of phase jump and loop cycle skipping is solved by using differential modulation quadrature differential phase shift keying with high frequency spectrum utilization rate, and the transmitter adopts demodulation and decoding combined iterative technology to eliminate inter-code interference. The method has the beneficial effects that 1) the error bit rate performance of a remote underwater sound communication system is improved by the demodulation and decoding combined iterative technology; 2) the technical requirement on a non-linear amplifier is reduced by differential modulation, and differential modulation has engineering feasibility; and 3) the multi-path interference of a remote underwater sound channel is overcome by spread spectrum communication.

The invention relates to a wireless multi-hop network technology, in particular to a receiving and transmitting method for realizing irrelevant receiving by a relevant network code. In order to improve the wireless multi-hop communication transmission efficiency and reduce the technical complexity and the communication error code rate, the method comprises the following steps of: carrying out relevant network PCNC coding in a source end physical layer; detecting and utilizing a unique mapping relation to map a detected signal into a de-noised mixed signal by a relay through the channel attenuation coefficient and carrying out differential modulation on the mixed signal to be transmitted to two mutually communicated source ends; during receiving at the source ends, realizing the irrelevant receiving under the condition of not learning any channel characteristic by a differential relation of signals before and after mapping by the mixed signal to recover a signal sum of the two continuous time slots and subtracting the signal at the local end to obtain a signal at the opposite end. The invention is mainly used for the transmission in wireless cooperative communication needing the relay and the transmission between a base station without a straight transmission line and a mobile terminal.

The present invention provides a differential relay cooperative communication method using quadrature amplitude modulation, which mainly solves the problem of poor bit error rate performance under high-order modulation in the prior art. The implementation steps are: (1) Compare the signal-to-noise ratio of the relay link, and select the one with the highest signal-to-noise ratio from multiple relay nodes as the best relay node; (2) The source node first constellates the transmitted information. Mapping and differential modulation, and then send the differentially modulated output signal to the destination node and the best relay node; (3) The best relay node first performs differential demodulation and differential modulation on the received signal, and then converts the differentially modulated The output signal is forwarded to the destination node; (4) The destination node first performs differential demodulation on the transmitted signal of the source node and the transmitted signal of the optimal relay node, and then performs maximum ratio combining on the output signals of the differential demodulation, and finally performs the maximum ratio combination on the maximum Constellation inverse mapping is performed on the combined output signal to obtain the source information. The invention can improve the bit error rate performance of the cooperative communication system.

The invention discloses an anti-eavesdropping double-differential bidirectional relay transmission method. A relay node broadcasts a known symbol sequence first, a source node estimates the channel energy between the source node and a relay, and an eavesdropping node estimates the channel energy between the eavesdropping nod and the relay; two source nodes respectively carry out double differential modulation, and send modulation signals to the relay, the relay carries out a conjugate operation to received mixed signals and then amplifies and forwards the mixed signals; finally, the source nodes carry out interference self-cancellation to the received signals and decode information of the received signals by means of the estimated local channel energy and the structure designed according to the method, and the eavesdropping node cannot decode the received signals correctly, and therefore the anti-eavesdropping aim is reached. Compared with an existing amplification and forwarding differential bidirectional relay transmission method, the anti-eavesdropping double-differential bidirectional relay transmission method is advantaged in that the transmission safety is achieved, and the source nodes can carry out decoding successfully under the condition of unknown carrier wave frequency offset existing in the system.

Where the additional data throughput is added using an amplitude offset or a combination of phase and amplitude offset, the legacy differential demodulator does not recover the amplitude information. The present invention provides a method for demodulating amplitude offsets in a differential modulation system in order to recover the amplitude information. The demodulated amplitude information may be used to recover the additional Level 2 data transmitted as an amplitude offset or combination phase and amplitude offset in a differential multiple phase shift keying (D-MPSK) transmission, such as across adjacent OFDM symbols and/or adjacent frequency subcarriers.