Abstract: Examples disclosed herein provide for a method for transmitting a signal. The method includes generating a Manchester encoded data stream and combining the Manchester encoded data stream with an amplified clock signal to produce an amplitude modulated signal having a zero crossing at each edge of the amplified clock signal. The amplitude modulated signal can then be sent over a communication medium.

Abstract: A device receives ASK signals by using an ASK signal receiving circuit that is different from an ASK signal receiving circuit for R/W mode, when an NFC-enabled semiconductor device operates in a mode other than the R/W mode. An ASK signal receiving circuit for 100% ASK is provided on the side of a pair of transmitting terminals. This arrangement eliminates the influence of an ESD provided within an ASK signal receiving circuit for 10% ASK coupled to a pair of receiving terminals. There is no need for management of threshold values that are different according to type of ASK and it is possible to support different modulation schemes by a smaller circuit configuration.

Abstract: In a receiver, a synchronization circuit (MIX2, OSC, C1, R1) provides a set of oscillator signals (OSI, OSQ) that are synchronized with a carrier of an amplitude-modulated signal. The set of oscillator signals (OSI, OSQ) comprises a quadrature oscillator signal (OSQ), which is substantially 90° phase shifted with respect to the carrier of the amplitude-modulated signal. A quadrature mixer (MIX2) mixes the quadrature oscillator signal (OSQ) with the amplitude-modulated signal so as to obtain a quadrature mixer output signal (MO2a). A phase-error corrector (PEC) adjusts the phase of the oscillator signals in response to a variation in the magnitude of an alternating current component (AC) in the quadrature mixer output signal (MO2a).

Abstract: Methods and apparatus for FEC frame header detection are provided, suitable for use in a DVB-C2 receiver. A first method comprises demodulating with a quadrature phase shift keying (QPSK) demapper, followed by correlation and symmetry measures for detection of a robust FEC header. A second method comprises demodulating with a 16 quadrature amplitude modulation (QAM) demapper, followed by correlation and symmetry measures for detection of a high efficiency FEC leader. Another embodiment comprises using both the first and second methods to find the FEC header because the first symbol of the FEC frame header may be sent either in robust mode or in high efficiency mode. There is also provided a method and apparatus for generating an alternate decision statistic for determining detection of the FEC frame header.

Abstract: A receiver receives a received signal from a communication link, the received signal comprising a stream of symbols modulated onto a carrier, each of the stream symbols selected from a constellation of symbols to represent a plurality of encoded data bits. The receiver comprises a demodulator to produce a stream of received symbols derived from the received signal; a channel decoder to produce a received stream of data bits derived from the stream of received symbols; and a memory device to store information related to the plurality of symbols in the constellation.

Abstract: A system, method and node for modulation and coding scheme adjustment for a Long Term Evolution (LTE) shared Data Channel. The method determines an actual number of orthogonal frequency division multiplexing (OFDM) symbols, NOS utilized for the shared Data Channel. A modulation order for transmission of data on the shared Data Channel is increased when the actual number of OFDM symbols NOS is less than 11 and decreased when NOS is more than 11. A modulation and coding scheme field (IMCS) of a downlink control information of the shared Data Channel may also be determined. If 0?IMCS+11?NOS?28, the modulation order is modified by utilizing a factor of (IMCS+11?NOS) in a standardized modulation scheme. If it is determined that IMCS+11?NOS<0, the modulation order is set to Quadrature Phase Shift Keying (QPSK). If it is determined that IMCS+11?NOS>28, the modulation order is set to 64 Quadtrative Amplitude Modulation (64QAM).

Abstract: An apparatus for recovering carrier wave in digital broadcasting receiver and a method therefore are disclosed which are capable of easily detecting and correcting frequency offsets of carrier wave without recourse to a pilot signal in a digital broadcasting receiver receiving a broadcasting signal of vestigial sideband (VSB) modulation system, thereby recovering the carrier wave, wherein, to this end, a complex sine wave whose central frequency is 1/n the symbol frequency is multiplied to generate a real component and imaginary Offset Quadrature Amplitude Modulation (OQAM) signals to calculate a phase error value from the real and imaginary component OQAM signals, to generate a complex sine wave compensating the calculated phase error value, to multiply the complex sine wave by the complex signal outputted from the phase splitter and to convert the complex signal to a baseband signal whose frequency offset is corrected.

Abstract: A phase-locking loop (PLL) for use with orthogonal frequency division multiplexed signals. In one embodiment, a wireless receiver includes a PLL is configured to reduce phase and frequency divergence between the wireless receiver and a transmitter of a packet received by the wireless receiver. The PLL includes a loop bandwidth controller. The loop bandwidth controller is configured to set a bandwidth of the PLL to a first value for reception of an initial symbol of the packet. The loop bandwidth controller is configured to reduce the bandwidth of the PLL over a number of symbols preceding an initial header of the packet.

Abstract: A method and apparatus are described that result in an improved acquisition of a received communication signal containing a large frequency offset. The method and apparatus raises a derotated sequence of data to a power of an integer provide a sinusoidal spectral component. The method and apparatus determines a cross product based upon the sinusoidal spectral component to provide a phase error. The method and apparatus determines an oscillator signal based upon the phase error. The method and apparatus adjusts the received communication signal based upon the oscillator signal to compensate for the large frequency offset to provide the derotated sequence of data.

Abstract: A demodulation circuit, a digital microwave system including the demodulation circuit, and a signal demodulation method are provided. The demodulation circuit includes a first circuit, a second circuit, a third circuit, and a fourth circuit connected in turn. The fourth circuit includes a pulse counting unit and a data decision unit connected in turn. The signal demodulation method includes: performing bandpass filtering on input signals; increasing gains of the bandpass filtered signals; extracting pulse signals are extracted from the gain-increased signals; counting the extracted pulse signals; filtering the pulse signals having counting values falling outside of a predetermined range, and outputting the filtered pulse signals.

Abstract: A method for extracting time information from a received, amplitude-modulated time signal is provided. The method provides that the time signal is demodulated, the analog signal thus obtained is digitized by a comparator, and the digital signal thus obtained is analyzed to extract the time information. In addition, a characteristic value of the time duration of at least one signal phase of a specific signal level of the digital signal is compared to a target value, and a comparator threshold of the comparator is altered as a function of a result of the comparison such that the time duration of at least the applicable signal phase of the digital signal approaches the target value. In this way, an improved system sensitivity is achieved according to the invention in a receiver for receiving time signals.

Abstract: A symbol detector with a sphere decoding method implemented therein. A baseband signal is received to determine a maximum likelihood solution using the sphere decoding algorithm. A QR decomposer performs a QR decomposition process on a channel response matrix to generate a Q matrix and an R matrix. A matrix transformer generates an inner product matrix of the Q matrix and the received signal. A scheduler reorganizes a search tree, and takes a search mission apart into a plurality of independent branch missions, wherein the search tree defines a full search depth Nfull. A plurality of Euclidean distance calculators are controlled by the scheduler to operate in parallel, wherein each has a plurality of calculation units cascaded in a pipeline structure to search for the maximum likelihood solution based on the R matrix and the inner product matrix.

Abstract: In a multivalue modulation type with one pilot symbol inserted for every 3 or more symbols, signal points of each one symbol immediately before and after a pilot symbol are modulated using a modulation type different from that for pilot symbols. In this way, it is possible to suppress deterioration of the accuracy in estimating the reference phase and amount of frequency offset by pilot symbols and improve the bit error rate characteristic in the signal to noise ratio in quasi-coherent detection with symbols whose symbol synchronization is not completely established.

Abstract: A demodulating system (100) for demodulating a phase-modulated input signal (Si) comprises: a complex demodulator (110), having a first input (111) for receiving the phase-modulated input signal (Si) and being designed to perform complex multiplication of this signal with an approximation of the inverse of the phase modulation; a spectrum analyzing device (130) receiving the demodulated product signal produced by the complex demodulator (110) and capable of analyzing the frequency spectrum of the demodulated product signal.

Abstract: A device for generating a modulation signal for an RF pulse transmitter is disclosed. The device includes a detector, a video amplifier, an analog processing device, and a modulation signal generating device. The modulation signal generating device is configured to receive an information cue from the analog processing device and to output the modulation signal. The modulation signal generating device includes a digital processing device and a signal generating device. The digital processing device is configured to receive a transmission synchro signal and the information cue and to generate a first control signal and a second control signal. The signal generating device is configured to generate a variable-amplitude Gaussian-shaped signal in response to the first control signal, to generate a variable-amplitude square-shaped signal in response to the second control signal, and to generate the modulation signal according to the Gaussian-shaped signal and the square-shaped signal.

Abstract: The present invention concerns a method for limiting interference received by a plurality of destinations, the interference being generated by plural flows of complex modulation symbols transferred by a plurality of sources on same resources of a wireless telecommunication network. The method comprises the steps executed by a relay of: receiving complex modulation symbols, decoding complex modulation symbols and successfully retrieving an information word from which the complex modulation symbols are derived, generating complex modulation symbols that will be transmitted by the source, pre-coding the generated complex modulation symbols by a pre-coding matrix, the pre-coding matrix being defined so as to reduce the interference generated by the flow of complex modulation symbols on the other flows of complex modulation symbols, transferring the pre-coded complex modulation symbols.

Abstract: Systems and methods are provided for decoding signal vectors in multiple-input multiple-output (MIMO) systems, where the receiver has received one or more signal vectors from the same transmitted vector. The symbols of the received signal vectors are combined, forming a combined received signal vector that may be treated as a single received signal vector. The combined signal vector is then decoded using a maximum-likelihood decoder. In some embodiments, the combined received signal vector may be processed prior to decoding. Systems and methods are also provided for computing soft information from a combined signal vector based on a decoding metric. Computationally intensive calculations can be extracted from the critical path and implemented in preprocessors and/or postprocessors.

Abstract: A configurable transceiver includes an RF receiver section that generates at least one downconverted signal from a received RF signal. A receiver processing module processes at least one downconverted signal in a plurality of receiver stages to produce a stream of inbound data, wherein the receiver processing module is configurable in response to a control signal to selectively bypass at least one of the plurality of receiver processing stages. A transmitter processing module processes outbound data in a plurality of transmitter stages to produce at least one baseband signal, wherein the receiver processing module is configurable in response to the control signal to selectively bypass at least one of the plurality of transmitter processing stages. An RF transmitter section generates at least one RF signal from the at least one baseband signal.

Abstract: A signal receiving apparatus has: a radius identifying section configured to identify a radius representing a distance from an origin on an IQ plane of signal points each corresponding to a symbol obtained from a received signal modulated by adoption of an APSK modulation method; and a parameter outputting section configured to output a control parameter related to a demodulation or decoding process of the received signal on the basis of the identified radius.

Abstract: A MIMO channel frequency response matrix is decomposed into a frequency-related part and a constant part. The constant part is independent of subcarrier index and of number of subcarriers in one symbol interval. Separated QR decomposition and either SVD or GMD is applied to the two parts. A right unitary matrix (R) is obtained from the SVD or GMD applied to the constant part. QR decomposition is applied to the constant part to generate a beamforming matrix (V). In another embodiment, a selection criterion based on a correlation matrix distance is used to select a beamforming matrix that is independent of subcarrier, the selected matrix is retrieved from a local memory and applied to a received signal. Noise covariance is computed for a noise expression which considers interference generated from the applied beamforming matrix. Data detection is performed on the received signal by a MIMO data detector using the noise covariance.

Abstract: Provided is a method for transmitting data in a communication or broadcasting system using a linear block code by generating a codeword by encoding input information data bits, interleaving the codeword; outputting modulation signal-constituting bits by bit-mapping the interleaved codeword using a bit-mapping table predetermined depending on a modulation scheme and a coding rate, outputting a modulation signal by modulating the modulation signal-constituting bits and transmitting the modulation signal via a transmit antenna.

Abstract: An integrated low-IF (low intermediate frequency) terrestrial broadcast receiver and associated method are disclosed that provide an advantageous and cost-efficient solution. The integrated receiver includes a mixer, local OSC oscillator generation circuitry, low-IF conversion circuitry, and DSP circuitry. And the integrated receiver is particularly suited for small, portable devices and the reception of terrestrial audio broadcasts, such as FM and AM terrestrial audio broadcast, in such portable devices.

Abstract: Implementation of Fast Information Channel (FIC) signaling when Chunks of FIC information span more than one sub-Frame of an M/H Frame is described. FIC signaling is advanced further at the digital television (DTV) transmitters than originally proposed, thereby eliminating need for substantial amounts of delay memory for coded M/H data in receivers for such data. Each FIC-Chunk includes a bit indicating when it is not applicable only to M/H Frames yet to be received but is also applicable to an M/H Frame being currently received. This facilitates reception being more quickly established after a change in DTV channel selection. Transmission Parameter Channel (TPC) signaling pertaining to the M/H Frame being currently received continues to the conclusion of the M/H Frame, so the total number of M/H Groups in each M/H sub-Frame is signaled to facilitate de-interleaving of the FIC signaling. Code combining of FIC Chunks is described.

Abstract: A radio apparatus includes a receiver which receives a wirelessly transmitted signal as a reception signal, a transmitter which is provided in the vicinity of the receiver and generates a transmission signal having a frequency different from that of the reception signal, and a reception signal extracting unit which extracts a reception signal from an input signal containing the reception signal and the transmission signal, at a timing of a zero crossing of the transmission signal in the input signal, by using phase information including the phase of the transmission signal from the transmitter.

Abstract: A demodulation circuit, a digital microwave system including the demodulation circuit, and a signal demodulation method are provided. The demodulation circuit includes a first circuit, a second circuit, a third circuit, and a fourth circuit connected in turn. The fourth circuit includes a pulse counting unit and a data decision unit connected in turn. The signal demodulation method includes: performing bandpass filtering on input signals; increasing gains of the bandpass filtered signals; extracting pulse signals are extracted from the gain-increased signals; counting the extracted pulse signals; filtering the pulse signals having counting values falling outside of a predetermined range, and outputting the filtered pulse signals.

Abstract: An apparatus and a method for operating a transmitter supporting constellation rearrangement for 256-Quadrature Amplitude Modulation (QAM) in a broadband wireless access system are provided. The method include generating complex symbols according to a first version of a constellation mapping rule, transmitting an initial transmit packet comprising the complex symbols, and when retransmitting the initial transmit packet, generating complex symbols according to a second first version of a constellation mapping rule.

Abstract: A system for detecting and correcting for spurious frequencies that may coincide in a bandwidth of interest in an RF metrology system. The system can (1) utilize a deterministic scheme to detect an interference by a spurious frequency and correct the distortion effect or (2) utilize a mixed signal processing architecture to avoid the occurrence of spurious frequency contamination. A detection scheme identifies the event of distortion and triggers either (a) a shift in the analog to digital convert sample rate or (b) a mathematical vector manipulation. The shift of the analog to digital convert sample rate moves an aliased image of the spurious frequency outside of the frequency of interest. The mathematical vector correction removes the distortion and restores the signal of interest.

Abstract: An amplitude-shift-keying radio-frequency (ASK RF) signal decoding method includes separating a low frequency and a high frequency from an ASK RF signal, which includes a pause section and a non-pause section, generating a divided signal by dividing the high frequency signal, counting the divided signal for the non-pause section of the low frequency signal, and decoding the ASK RF signal based on a result of the counting.

Abstract: A data carrier detector for a packet-switched communication network. The detector includes an envelope detector to provide peak-to-peak amplitude of an incoming waveform at any given time, a peak-to-peak amplitude monitor to monitor peak-to-peak amplitude, and to set a trigger when the peak-to-peak amplitude changes by a predetermined amount. The detector also includes a data packet searcher to start searching for a data packet when the peak-to-peak amplitude monitor issues the trigger. The detector further includes a data packet processor to process and extract information from the recovered data packet.

Abstract: Disclosed is a method, circuit and system for transmission and reception of data, including video data. There is provided a multi-constellation data to symbol mapping logic, circuit or module integral with or otherwise functionally associated with a transmitter and a corresponding multi-constellation symbol to data de-mapping logic, circuit or module integral or otherwise functionally associated with a receiver. The multi-constellation mapping and corresponding de-mapping logic, circuit or module may be characterized by a non-uniform distribution of symbols, and optionally may be characterized by a set of symbol clusters, wherein symbol clusters are of the same or varying sizes and may be spaced either at uniform or non-uniform distances from one another.

Abstract: Provided is a measuring apparatus which measures a quadrature modulator, including a supplying section supplying the quadrature modulator with a reference I signal having a predetermined frequency and a reference Q signal whose phase is shifted by 90 degrees from the reference I signal, an extracting section extracting, from a modulation signal output from the quadrature modulator by applying quadrature modulation to the reference IQ signals, a main signal component as the reference IQ signals modulated, and an image signal component occurring at a position symmetric to the modulated reference IQ signals with respect to the carrier signal, and a measurement value calculating section calculating at least one of a carrier phase error and amplitude error which occur between I signal and Q signal sides of the quadrature modulator, and a skew between IQ signals of the quadrature modulator, based on the main signal component and image signal component.

Abstract: The carrier phase of a carrier wave modulated with information symbols is recovered with a multi-stage, feed-forward carrier phase recovery method. A series of digital signals corresponding to the information signals is received. For each digital signal, a coarse phase recovery is performed to determine a first phase angle which provides a first best estimate of the information symbol corresponding to the digital signal. Using the first best estimate as input, a second stage of estimation is then performed to determine a second phase angle which provides an improved (second) best estimate of the information symbol. Additional stages of estimation can be performed. The multi-stage, feed-forward carrier phase recovery method retains the same linewidth tolerance as a single-stage full blind phase search method; however, the required computational power is substantially reduced. The multi-stage, feed-forward carrier phase recovery method is highly efficient for M-QAM optical signals.

Abstract: The present invention relates to a method of transmitting and a method of receiving signals and corresponding apparatus. One aspect of the present invention relates to an efficient layer 1 (L1) processing method for a transmitter and a receiver using data slices.

Abstract: Aspects of a method and system for channel estimation in a SM MIMO communication system may comprise receiving a plurality of spatially multiplexed communication signals from a plurality of transmit antennas. A plurality of baseband combined channel estimates based on phase rotation may be generated in response to the received plurality of spatially multiplexed communication signals. An estimate of the channel matrix may be determined based on the baseband combined channel estimates. A plurality of amplitude and phase correction signals may be generated in response to receiving the estimate of the channel matrix. An amplitude and a phase of at least a portion of the received plurality of spatially multiplexed communication signals may be adjusted based on the generated plurality of amplitude and phase correction signals, respectively.

Abstract: A method of processing a signal in a wireless network including multiple chains is provided. This method can include receiving the signal in a receiver and, for each chain, performing a Barker correlation on the signal to generate a Barker correlated signal. At this point, an autocorrelation can be performed on the Barker correlated signal to generate an autocorrelated signal. The autocorrelated signals from the multiple chains can be summed to generate a summed output. Additional processing, e.g. at least one of CCK weak signal detection, peak selection in a rake receiver, frequency estimation, and differential decoding, can then be performed based on the summed output.

Abstract: The present invention relates to a method of transmitting and a method of receiving signals and corresponding apparatus. One aspect of the present invention relates to an efficient L1 signaling method for an efficient transmitter and an efficient receiver using the efficient L1 signaling method for an efficient cable broadcasting.

Abstract: Disclosed herein are systems and methods for accurate removal of I/Q mismatch in received signals of an analog FM receiver. The analog FM receiver includes a down-converter, a calibration circuit that estimates I/Q mismatch values, and a compensation circuit that uses the estimated mismatch values to reduce the effects of I/Q mismatch. In one aspect, the calibration circuit uses an adaptive dual-parameter compensation scheme to iteratively correct the received signals by approximating a coefficient value and an amplitude value that minimize the signals' amplitude variation from the amplitude value. In another aspect, phase and amplitude mismatch parameters can be determined using the coefficient value.

Abstract: Techniques for data transmission using high-order modulation are provided. According to one aspect, parameters of a transmission link are determined, and a multilevel coding scheme and a high-order modulation signal constellation are selected on the basis of the determined parameters. An information indicating the selected multilevel coding scheme and high-order modulation signal constellation and data symbols encoded according to the selected multilevel coding scheme and high-order modulation signal constellation are transmitted. In other aspects, QPSK data symbols are embedded between M-QAM data symbols or M-PSK data symbols with M>4. The QPSK data symbols may be used to improve the efficiency of the decoding process.

Abstract: A receiving circuit and method for receiving an amplitude shift keying signal is provided. At least one exponent signal, an exponent-removed in-phase signal, and an exponent-removed quadrature-phase signal are generated from an in-phase input signal and a quadrature-phase input signal. An amplitude is determined as a sum of several summands, whereby the summands are determined from the exponent signal and/or from the exponent-removed in-phase signal and/or from the exponent-removed quadrature-phase signal (Q?), and wherein the amplitude (A) is demodulated.

Abstract: An amplitude-shift-keying radio-frequency (ASK RF) signal decoding method includes separating a low frequency and a high frequency from an ASK RF signal, which includes a pause section and a non-pause section, generating a divided signal by dividing the high frequency signal, counting the divided signal for the non-pause section of the low frequency signal, and decoding the ASK RF signal based on a result of the counting.

Abstract: The invention relates to methods for transmitting and receiving a data bit stream in a communication system using 16-QAM constellations. Further, an apparatus for performing the methods is provided. To improve the bit-error rate performance of the communication using the 16-QAM constellations the invention suggests the use 16-QAM constellations with specially selected mapping rules together with a special constellation rearrangement for creating different versions of the 16-QAM constellations. Further, the data stream is transmitted according to a diversity scheme employing different versions of the 16-QAM constellations obtained adhering the mapping rules and rearrangement rules defined by the invention.

Abstract: A DHT-based OFDM transmitter and receiver use discrete Hartley transform to implement multicarrier transmission. A transmission terminal (or a receiving terminal) of a transmitter and receiver comprises two IDHT (or DHT) processors and a diagonal processing device. The two IDHT processors make the DHT-OFDM system transmit the 2D modulation signal to increase the bandwidth efficiency. The diagonal processing device is used to diagonalize the circulant channel matrix into discrete memoryless subchannels, and thus only one-tap frequency domain equalizer can compensate the channel effects. Besides, the proposed DHT-OFDM transmitter and receiver are also compatible with a conventional DFT-OFDM system, and they can flexibly works with the conventional DFT-OFDM transmitter and receiver.

Abstract: Certain aspects of a method and system for independent in-phase (I) and quadrature (Q) loop amplitude control for quadrature generators may include determining an amplitude voltage associated with an in-phase (I) component and a quadrature (Q) component of a generated signal. A DC reference voltage associated with the I component and the Q component may be determined. The determined amplitude voltage may be compared with the determined reference voltage to generate a control signal. The amplitude mismatch between the I component and the Q component may be compensated by controlling a biasing current of one or more programmable buffers associated with one or both of the I component and the Q component, based on the generated control signal.

Abstract: An amplitude detecting device of the present art increases the slope of the change in output voltage corresponding to the change in amplitude of an input signal to improve the detection accuracy of amplitude change of input signal, without changing the dynamic range of the device. An amplitude detecting device of the art includes a plurality of amplifiers that amplify an input signal according to a predefined amplification rate, an amplitude detector that detects the amplitude of the signal amplified by the amplifiers, an operation circuit that operates the signal detected by the amplitude detector and obtains the amplitude value of the input signal, and a switch circuit that sets whether the signal detected by the amplitude detector is to be transmitted to the operation circuit or not.

Abstract: The invention relates to methods for transmitting and receiving a data bit stream in a communication system using a 16-QAM constellation. Further, an apparatus for performing the methods is provided. To provide a modulation and coding scheme using a signal space expansion and 16-QAM which improves the bit-error rate in comparison to QPSK modulated signals and still provides the possibility to implement coders and decoders with low complexity the invention suggests the use a 16-QAM constellation with specially selected mapping rules together with repetition coding (signal space expansion) and interleaving of the data stream to be transmitted.

Abstract: A system and method for accelerated performance of quadrature amplitude modulation (QAM) is provided. The system includes multiple general purpose registers and multiple execution units configured to decode a set of QAM tones in parallel or an individual QAM tone in response to a single instruction executable by the processor. Each of the plurality of execution units is configured to decode one of the set of QAM tones according to a constellation size associated with the one of the set of QAM tones. The QAM decoding method includes reading a constellation size value for each of a set of received input tones. For each tone in the set of input tones, an ideal point in a QAM constellation of the associated constellation size closest to the X and Y coordinates of the tone is determined. The data values of the ideal points are then stored in a destination register.

Abstract: Compact pulse shape partial response (CPS PR) signaling is developed for trellis based signals like QM-MSK, and for PAM/QAM type signals to improve the performance to bandwidth tradeoff. Compact pulse shaped signals are partial response signals that employ a very short pulse shaping filter and use Viterbi decoding to optimally detect the CPS signal in presence of its inherent inter-symbol interference. The CPS filters considered herein have much shorter impulse response than the well-known raised cosine (RC) filter. There is no need to equalize the received signal to eliminate ISI or to allow a fixed amount of ISI between received signal samples as sampled at the symbol rate as is common in partial response maximum likelihood (PRML) systems. Numerical results indicate that CPS QM-MSK and CPS QAM provides between several dB of gain, depending on constellation size, over PR-CPM and RC QAM, when compared at a given value of bandwidth, i.e., B99Tb.

Abstract: A mechanism for jointly correcting carrier phase and carrier frequency errors in a demodulated signal. A computer system may receive samples of a baseband input signal (resulting from QAM demodulation). The computer system may compute values of a cost function J over a grid in a 2D angle-frequency space. A cost function value J(?,?) is computed for each point (?,?) in the grid by (a) applying a phase adjustment of angle ? and a frequency adjustment of frequency ? to the input signal; (b) performing one or more iterations of the K-means algorithm on the samples of the adjusted signal; (c) generated a sum on each K-means cluster; and (d) adding the sums. The point (?e,?e) in the 2D angle-frequency space that minimizes the cost function J serves an estimate for the carrier phase error and carrier frequency error. The estimated errors may be used to correct the input signal.

Abstract: A method and arrangement for estimating a DC offset for a signal received in a radio receiver. The received signal includes a digitally modulated signal component, a DC offset component, and a noise component. When the signal is of a known type, such as a Gaussian Minimum Shift Keying (GMSK)-modulated signal with constant amplitude in a GSM/EDGE cellular radio system, the method exploits the known characteristics of the statistical distribution for the known type of signal to obtain a better estimate of the DC offset. The statistical distribution of the received digitally modulated signal component is first analyzed. That statistical distribution is then compared to the known statistical distribution for the known type of signal to identify differences. The differences are then used to estimate the DC offset. Additional iterations may be performed to further improve the DC estimate.

Abstract: An amplitude modulation (AM) demodulating circuit applied to a radio frequency identification (RFID) system attenuates carrier signals by a notch filter to increase a signal-to-carrier ratio and to reduce complexity and cost of circuit design. The AM demodulating circuit includes an envelope detector, a notch filter, a low-pass filter, and a comparing circuit. The envelope detector performs envelope detection on an AM signal modulated by a carrier frequency to generate an envelope signal. The notch filter filters the envelope signal to generate a first filtered signal, and a zero point of the notch filter corresponds to the carrier frequency of the AM signal. The low-pass filter filters the first filtered signal to generate a second filtered signal, and the carrier frequency of the AM signal corresponds to a stop band of the low-pass filter. The comparing circuit converts the second filtered signal to a digital signal according to a level value.