Abstract: Systems and methods for receiving layered modulation for digital signals are presented. An exemplary apparatus comprises a tuner for receiving a layered signal and producing a layered in-phase signal and a layered quadrature signal therefrom, an analog-to-digital converter for digitizing the layered in-phase signal and the layered quadrature signal and a processor for decoding the layered in-phase signal and the layered quadrature signal to produce one or more discrete layer signals.

Abstract: Unlike a prior art digital predistortion compensation device for determining a compensation coefficient based on absolute value information about a baseband complex input signal, the present invention performs distortion compensation calculation in accordance with a complex coefficient polynomial using real and imaginary parts of the baseband complex input signal as its variables.

Abstract: A method for transmitting and receiving an uncompressed HDTV signal over a wireless RF link includes steps of: providing a clock signal synchronized to the uncompressed HDTV signal; and providing a stream of regenerated data from the uncompressed HDTV signal, with the clock signal synchronized to the stream of regenerated data. The clock signal is then used for demultiplexing the stream of regenerated data into an I data stream and a Q data stream. The method further includes steps of: modulating a carrier with the I data stream and the Q data stream; transmitting the carrier over the wireless RF link; demodulating the carrier so that the I data stream and the Q data stream are recovered; multiplexing the I data stream and the Q data stream into a single stream of HDTV data; and recovering the uncompressed HDTV signal from the single stream of HDTV data.

Abstract: A new class of 16-ary Amplitude and Phase Shift Keying (APSK) coded modulations, called double-ring APSK modulation, based on an amplitude and phase shift keying constellation in which the locations of the digital signals to be encoded are placed on two concentric rings of equally spaced signal points. The APSK constellation parameters are optimised so as to pre-compensate the impact of non-linearities. The new modulation scheme is suited for being used with different coding schemes. It is shown that, for the same coding scheme, pre-distorted double-ring APSK modulation significantly outperforms classical 16-QAM and 16-PSK over a typical satellite channel, due to its intrinsic robustness against the high power amplifier non-linear characteristics. The proposed coded modulation scheme is shown to provide a considerable performance advantage for future satellite multi-media and broadcasting systems.

Abstract: An RF ASIC for a subscriber communicator includes a receiver section, a transmitter section, a CODEC and an I2S port. The receiver section downconverts by superheterodyning and demodulates a received RF communication signal to provide analog quadrature components of the received signal at baseband. The transmitter section upconverts and combines analog input quadrature modulation components to provide an RF communication transmit signal and then amplifies the transmit signal for driving an external power amplifier. The CODEC processes the analog baseband quadrature components of the received signal to provide I and Q digital output signals, and processes I and Q digital input signals to provide the analog input quadrature modulation components for said upconversion. The I2S port combines the I and Q digital output signals for output as a serial digital signal stream, and separates the I and Q digital input signals from an input serial digital signal stream.

Abstract: Method and apparatus for high speed wireless transmission involving selective PSK coding techniques are disclosed. In particular, to enhance effective throughput while maintaining a channel footprint backwards compatible with existing IEEE 802.11 and 802.11b (1999) standards, the payload of outbound data packets are selectively modulated using DQPSK techniques at the CCK symbol chipping rate. This results in a 22 Mbps effective throughput, a 2× improvement over the 802.11b standard. A complementary receiver includes a DQPSK demodulation pathway suitable for decoding inbound data packets at the 11 MHz CCK chipping rate but bypassing the conventional CCK encoder, resulting in a 22 Mbps data stream. Backwards compatibility with legacy 802.11 and 802.11b devices is partially accommodated using a data packet format similar to the conventional PLCP frame format but for the data transmission rate and use of heretofore reserved bits, causing legacy devices to ignore such packets.

Abstract: A spread spectrum transmitter provides delays having different magnitudes to spread spectrum (SS) signals for a plurality of channels, and multiplexes the SS signals to generate transmission multiplex SS signal. A spread spectrum receiver calculates a partial correlation value between the transmission multiplex SS signal and spreading codes multiplied to the SS signals, multiplies the partial correlation values by a prescribed matrix prepared based on each orthogonal code sequence to calculate a plurality of orthogonal correlation values. The receiver identifies for a respective channel each parallel data sequence related in advance to an orthogonal code sequence whose orthogonal correlation value is a maximum, corrects delay differences of the parallel data sequences, and then performs sampling and parallel-serial conversion to obtain a serial demodulated data sequence.

Abstract: A polyphase receiver comprises an RF front end (10 to 28) for receiving a wanted data signal modulated on a carrier signal and for producing quadrature related low IF signals, an image rejection filter formed by a polyphase filter (30) for filtering the quadrature related low IF signals, soft limiting means (36,38) for compressing the dynamic range of the filtered quadrature related IF signals and a signal demodulator (41) for recovering the data signal. The soft limiting means (36,38) has a characteristic which is substantially linear at signal levels 10 dB below a predetermined minimum wanted signal level, moves into compression for higher signal levels and hard limits at substantially 10 dB above the desired receiver sensitivity which avoids degrading the sensitivity of the receiver.

Abstract: Variable code rate and signal constellation turbo trellis coded modulation (TTCM) codec. A common trellis is employed at both ends of a communication system (in an encoder and decoder) to code and decode data at different rates. The encoding employs a single TTCM encoder whose output bits may be selectively punctured to support multiple modulations (constellations and mappings) according to a rate control sequence. A single TTCM decoder is operable to decode each of the various rates at which the data is encoded by the TTCM encoder. The rate control sequence may include a number of rate controls arranged in a period that is repeated during encoding and decoding. Either one or both of the encoder and decoder may adaptively select a new rate control sequence based on operating conditions of the communication system, such as a change in signal to noise ratio (SNR).

Abstract: Metric calculation design for variable code rate decoding of broadband trellis, TCM (trellis coded modulated), or TTCM (turbo trellis coded modulation). A single design can accommodate a large number of code rates by multiplexing the appropriate paths within the design. By controlling where to scale for any noise of a received symbol within a received signal, this adaptable design may be implemented in a manner that is very efficient in terms of performance, processing requirements (such as multipliers and gates), as well as real estate consumption. In supporting multiple code rates, appropriately selection of the coefficients of the various constellations employed, using the inherent redundancy and symmetry along the I and Q axes, can result in great savings of gates borrowing upon the inherent redundancy contained therein; in addition, no subtraction (but only summing) need be performed when capitalizing on this symmetry.

Abstract: A high-speed serial data transceiver includes multiple receivers and transmitters for receiving and transmitting multiple analog, serial data signals at multi-gigabit-per-second data rates. Each receiver includes a timing recovery system for tracking a phase and a frequency of the serial data signal associated with the receiver. The timing recovery system includes a phase interpolator responsive to phase control signals and a set of reference signals having different predetermined phases. The phase interpolator derives a sampling signal, having an interpolated phase, to sample the serial data signal. The timing recovery system in each receiver independently phase-aligns and frequency synchronizes the sampling signal to the serial data signal associated with the receiver. A receiver can include multiple paths for sampling a received, serial data signal in accordance with multiple time-staggered sampling signals, each having an interpolated phase.

Abstract: A modulator circuit comprises a negative impedance amplifier which is operable such that a signal applied to the amplifier is reflected and amplified. Switching circuitry is provided for switching the impedance of the amplifier between two reflecting states such that the reflected and amplified signal is phase modulated. The impedances of the negative impedance amplifier are selected such that the phase of the reflected and amplified signal switches by substantially 180°. Preferably, the impedances of the negative impedance amplifier in the two reflecting states are selected such that the reflection gain of the amplifier in the two reflecting states is substantially the same such that the reflected and amplified signal is a binary phase shift keyed.

Abstract: Various mixer topologies, configured to cancel various low order spurs. The mixer topologies each include a pair of mixers and a plurality of couplers. The couplers are configured to cancel specific spurs. As such, the mixer topology eliminates the need for band splitting thus allowing larger input frequency ranges and allows for simpler and less expensive filtering.

Abstract: A method for adjusting a phase angle (?) of a phase modifier (25) of a transmitting device which includes a quadrature modulator (3), a power amplifier (9), a quadrature demodulator (19) and differential amplifiers (26, 27). The power amplifier (9) is linearized via the feedback loop (16) according to the Cartesian feedback method. The phase modifier (25) supplies an oscillator signal to the quadrature demodulator (19), which signal is shifted by the phase angle (?) to be adjusted with regard to the oscillator signal that is supplied to the quadrature modulator (3). An input signal with a constant inphase component (I) and a constant quadrature phase component (Q) is applied during each transmission burst in the instance of a closed feedback loop, and the quadrature component (VQM) and/or the inphase component (VIM) is measured at a measuring point (53, 61) located behind the output of the differential amplifiers (26, 27).

Abstract: A method and apparatus are provided that generate, transmit, or receive a training sequence in a communications system, where the training sequence exhibits certain desirable characteristics when used by a peak to average power constrained modulation formal. In one embodiment, the invention includes selecting an original training sequence from a set of possible original training sequences having at least one desired property, forming a modified training sequence by modifying the original training sequence based on a corresponding modifying sequence, such that the modified training sequence exhibits the desired property of the original training sequence when used in a peak to average power constrained modulation format that would otherwise impair the desired property of the original training sequence.

Abstract: Method and radiofrequency apparatus comprising at least one transmitter and/or one receiver of one or more useful signals comprising at least one device adapted to applying a coefficient to the useful signal or signals. Application to BPSK to QPSK type modulation.

Abstract: A method of and apparatus for adapting an antenna array for closed loop transmit diversity, the method comprising: receiving an adapting signal corresponding to an antenna array weighting pattern for a time period; demodulating the adapting signal to provide a symbol for the time period; determining a preferred symbol from the symbol for the time period and a previous symbol for a previous time period; and transmitting with an antenna array weighting pattern corresponding to the preferred symbol.

Abstract: The present invention relates to a method and a device for the I/Q demodulation of modulated RF signals. The I/Q demodulator (60) has a first input for the RF signal (61) to be demodulated and a second input for a RF signal (62) originating from a local oscillator (20). The demodulator (60) combines the two RF signals (61,62) to generate three output signals supplied to three power detectors. In a combination unit (70) the three power signals of the power detectors are merged in two signal branches wherein after passing an A/D converting (72) and digital processing unit (73) one signal is the I component and the other one is the Q component of the received modulated RF signal (61).

Abstract: A BS digital broadcasting receiver which eliminates the uncertainty of an ODU's phase noise-dependent switching point when switching a receiving system. The receiver is provided with a demodulator circuit (6A) having a carrier regenerating circuit (19A) based on demodulation data in a BPSK modulation section, and with a demodulator circuit (6B) having a carrier regenerating circuit (19B) based on demodulation data in each time-division modulation section, wherein, when a lock for carriers regenerated by the carrier regenerating circuit (19A) is maintained and carriers regenerated by the carrier regenerating circuit (19B) is locked, demodulation data, in the BPSK demodulation section and a QPSK demodulation section, output from the demodulator circuit (6A) and 8-PSK-modulated demodulation data output from the demodulator circuit (6B) are selected by a selector (7) for outputting.

Abstract: A receiver includes an I-Q demodulator (135) responsive to the I and Q components carried on a first frequency signal line (132). A demodulator frequency generator (275) generates a demodulating signal to extract the carried I and Q components. A phase adjustment circuit (105) makes the demodulating signal substantially in phase with the first frequency signal. A transition detector (445) generates a state transition signal in response to a change of state of at least one of the I and Q signals. A peak detector (460) generates a peak detected signal in response to occurrence of a peak amplitude of at least one of the I and Q signals. A clock generator (470) adjusts the phase of a symbol clock signal used to decode the I and Q components in response to the state transition signal and peak detected signal.

Abstract: A frequency and phase synchronizer system comprises a processor for executing a sequence of operations, which include: a) initializing a frequency error estimate value and phase error estimate value; b) separating discrete samples of a continuous phase modulation signal into a first sequence of odd numbered samples of the signal, and a second sequence of even numbered samples of the signal; c) determining an unknown frequency offset value from the first and second sequences, frequency error estimate, and phase error estimate; d) determining an unknown phase offset value from the first and second sequences, frequency error estimate, phase error estimate, and a first discrete data sample of said discrete samples of the continuous phase modulation signal; f) updating the frequency error estimate from the unknown frequency offset value; and updating the phase error estimate from the unknown phase offset value.

Abstract: A system for MPSK symbol hypothesis testing. A received symbol having in-phase (I) and quadrature (Q) components is input to the system. Multipliers for each of the components are determined corresponding to the MPSK symbol hypothesis s being tested. The symbol s is a quadrature symbol having in-phase and quadrature components, sI and sQ, respectively. The multipliers are each derived from fractions which approximate to a desired level of resolution either ±sI or ±sQ. The system multiplies the I and Q components by their respective multipliers through a discrete series of add, shift, and twos complement operations. It then derives a metric for testing the hypothesis from the resulting products.

Abstract: A method is presented for increasing data throughput in a communications channel comprising the steps of selecting a first data packet from a queue of data packets to be transmitted over a communications channel, modulating said first data packet using a first modulation scheme, selecting a second data packet from a queue of data packets to be transmitted over the communications channel, modulating the second data packet using a second modulation scheme overlaying the first data packet on a symbol by symbol basis, transmitting the first data packet overlaid with second data packet over the communications channel, determining whether the first data packet was received by monitoring using the first modulation scheme for an acknowledgment for the first data packet before expiration of a timeout period, determining whether the second data packet was received by monitoring using the first modulation scheme for an acknowledgment for the second data packet before expiration of the timeout period and repeating the st

Abstract: Disclosed is a noncoherent pulse position and phase shift keying (PPPSK) transmission/reception system and a transmission/reception signal processing method therefor. Transmission system has an information generation unit for generating information data; a modulation unit for deciding a phase and a timing position corresponding to generated information data; and a wavelet generation unit for generating a wavelet based on the decided phase and timing position, and the reception system has an offset unit for mixing the reception signal with a high-frequency component corresponding to a center frequency of a transmission frequency band and offsetting a high frequency of the reception signal; a demodulation unit for generating at least one reference signal based on a previous signal precedingly received with respect to the reception signal and mixing the reference signals and the reception signal; and a decision unit for deciding information data corresponding to the reception signal based on mixing results.

Abstract: With respect to a digital modulation signal outputted from an output terminal, in order to enable desired carrier leak characteristics to be compatible with desired mutual modulation distortion characteristics according to a measurement object, a first level varying member is provided between an amplifier and an output terminal. In addition, a second level varying member is provided between a base band signal generator and an orthogonal modulator. The first and second level varying members are respectively set to be predetermined attenuation quantity values based on an output level value of a digital modulation signal specified by an output level specifying member and the judgment result caused by a judgment portion.

Abstract: In response to changes in an input binary digital signal, a 3rd order cosine pulse waveform, which, when it is changed in the increasing direction, has “0” level in a first period of T/12 (T corresponding to one-half cycle of the binary digital signal), is changed as a waveform of (h/2)(1+cos(3?t/T)+?/4) in the next period of 4T/12 (?5T/12?t??T/12) and has an h (constant) level in the remaining period of T/12, and when it is changed in the reducing direction, has the h level in the first period of T/12, is changed as a waveform of (h/2)(1+cos(3?t/T)??/4) in the next period of 4T/12 (T/12?t?5T/12) and also has “0” level in the remaining period of T/12. By using this pulse wave, a flat part is generated in a time width of T/12 with respect to a judgment point. It is thus possible to improve the immunity to the effects of digital signal jitter, obtain change judgment with a sole single pulse and reduce the circuit scale and the power consumption.

Abstract: There is disclosed a radio frequency (RF) modem shelf for use in a fixed wireless access network comprising a plurality of base stations capable of bidirectional time division duplex (TDD) communication with wireless access devices disposed at a plurality of subscriber premises.

Abstract: A method and system for providing communication between electronic devices that uses the phase of data transmitted between the devices to indicate logical one and zero values. The method and system has the added benefit of relieving the traditional limitations of voltage communication restraints between devices having differing core voltages (i.e. Differing generations).

Abstract: A method for demodulation of a phase shift keyed signal in which the phase shift keyed signal is converted into a plurality of successive outputs, each of which is representative of a phase and amplitude of the phase shift keyed signal over additional sets of windows and carrier phases. Each said additional set has a different offset in time and carrier phase from the other additional sets of windows and carrier phases. The carrier phase and window offsets of the phase shift keyed signal are estimated using the plurality of successive outputs. The phase shift keyed signal is then decoded back into digital data using the estimates.

Abstract: The invention relates to a system for electromagnetic processing of an input wave involving receiving a modified signal derived from two or more signals that represent the input wave when combined; and alternately regulating the modified signal using a digital signal containing at least one characteristic of said two or more signals. The invention may utilize in-phase and quadrature phase signals, where the magnitude portion of the signals may be used for regulating the modified signal. The modified signal may be created by modulating a characteristic of the I, Q signals, such as their sign, with an RF or other frequency carrier wave.

Abstract: Apparatus, and an associated method, by which to form biorthogonal codes utilized in a multi-dimensional modulation scheme. In one implementation, biorthogonal coding is provided in a cellular communication system in a manner that minimizes correlation of pairs of coordinates utilized in the communication system. Data that is to be communicated by a sending station is first modulated by a binary phase shift keying modulation. These first-modulated values are used by a mapper that maps the values to selected dimension values. And, the selected dimension values into which the first-modulated values are mapped are used to select biorthogonal code values.

Abstract: A multiple phase shift keying (MPSK) spread spectrum communications receiver uses weighted correlation techniques for carrier recovery and tracking. The receiver includes three subsystems: a synchronization system, a carrier tracking system, and a data demodulation system. To demodulate the received signal, the receiver requires a carrier frequency that matches the frequency of an associated transmitter as well as the sampling (or chip) and symbol clocks that are synchronized with those of the transmitter. In the disclosed receiver, the carrier tracking subsystem continually tracks the carrier frequency of the received signal using a tracking scheme that uses weighted correlation techniques. The weighted correlation technique combines signals from two correlator modules, an R-correlator module and a W-correlator module, to generate the correlation output. The R-correlator is similar to conventional correlators. The W-correlator, however, is unlike conventional correlators.

Abstract: 8 PSK (Phase Shift Keying) rotationally invariant turbo trellis coded modulation without parallel transitions. A novel approach of coding 8 PSK symbols such that they are rotationally invariant employs precoding and encoding according to Turbo Trellis Coded Modulation (TTCM). Together, the preceding and TTCM encoding operate cooperatively to provide rotational invariance of the 8 PSK symbols. These 8 PSK symbols are mapped to constellation points within an 8 PSK constellation. A permutated mapping of the 8 PSK constellation is also employed that describes an approximate 90 degree rotation of the 8 PSK constellation mapping. In addition, the precoding employs an induced precoder mapping that corresponds to the approximate 90 degree rotation of the mapping of the 8 PSK constellation. Moreover, the branches of the trellis employed within the TTCM encoding may undergo an appropriately modified mapping to accommodate the 90 degree rotation of the 8 PSK constellation mapping as well.

Abstract: Data pieces representative of in-phase components and quadrature components of a digital-modulation-resultant signal are assigned to frequencies for inverse fast Fourier transform. The inverse fast Fourier transform is executed at a predetermined sampling frequency Fs to convert the data pieces into a real-part signal and an imaginary-part signal. Phases of the real-part signal and the imaginary-part signal are shifted. Each of the phase-shifted real-part signal and the phase-shifted imaginary-part signal is divided into a sequence of even-numbered samples and a sequence of odd-numbered samples. A digital quadrature-modulation-resultant signal is generated from further manipulation of the even-numbered and odd-numbered samples.

Abstract: Communications systems, and particularly portable personal communications systems, such as portable phones, are becoming increasingly digital. One area that has remained largely analog, however, is the modulation and RF amplifier circuits. To produce a RF frequency waveform. An output of a class D amplifier is coupled to an integrator to create an analog signal. A resonant circuit shapes an output waveform based on the analog signal to create a sinusoidal RF broadcast signal. The waveform of the class D amplifier may be duty cycle modulated. Digital modulation may occur using a digital sigma delta modulator or a digital programmable divide modulator. Using the digital modulation techniques and class D amplification techniques together allows for broadcast a PSK signal that has been decomposed into amplitude and phase components.

Abstract: An nth root transformation is used for generating near Gaussian metrics from non-Gaussian metrics for input into a conventional turbo decoder that is based on the assumption that the input sequence to the decoder has a Gaussian distribution. The nth root transformation transforms channel non-Gaussian statistics to near Gaussian statistics for use with conventional turbo decoding for improved noncoherent communications over a non-Gaussian channel, such as a fading channel. For a differential coherent PSK waveform, where the channel statistics of a demodulator are non-Gaussian, for example, in the presence of fading, the nth root transformation is used to transform the non-Gaussian statistics to near Gaussian statistics for generating near Gaussian metrics, for improved PSK communications.

Abstract: An apparatus and method of detecting signals transmitted via frequency-shift keying techniques. An observation window encompassing a frequency band is defined and searched for received tones, the frequency spacing between received tones is calculated and compared to known FSK modulation techniques to determine whether at least part of a transmission is potentially present. The transmission may be an automatic link establishment signal. A histogram can store data on received tones. The observation window can be shifted to center a potential FSK transmission for parallel modem processing that will attempt to demodulate and decode it.

Abstract: A BS digital broadcast receiver having no 8PSK-demapper and a less number of delay circuits for Trellis encoding. A QPSK baseband signal based upon a reception signal point position of an absolute-phased baseband demodulation signal is Viterbi-decoded by a Viterbi-decoder 6. An output of the Viterbi-decoder is convolution-reencoded by a convolution encoder 7. Upper four bits of phase error data are searched from a phase error table 31 for carrier reproduction in accordance with a phase difference between 0 degree and a phase of a phase error detection reception signal point position. The upper four bits are delayed by delay circuits 81 to 84 by a total sum of a time taken to Viterbi-decode and a time taken to convolution-encode. The delayed outputs are demapped by a demapped value conversion circuit 9. A code TCD2 determined from the demapped output and convolution encode output is output as an MSB of a Trellis 8PSK decode output from an MSB code judging/error detecting circuit 10.

Abstract: A method (50) of operating a communications receiver (20). The method receives a communications signal (10) which is transmitted via a channel, where the communications signal comprises received known pilot data (DP) and received information data (DI), the known pilot data and information data being sequentially transmitted. The method then estimates a first channel impulse response (52) for the channel, wherein the first channel impulse response is in response to the received pilot data. Next, the method determines (54) a group of estimated information data in response to the first channel impulse response. Next, the method estimates a second channel impulse response (56) for the channel in response to the estimated information data. Thereafter, the method forms (56) a combined channel impulse response for the channel, using differing weights as applied to the first and second channel impulse responses.

Abstract: A small scale circuit can be realized. A timing circuit 30 detects a burst symbol signal period from outputs I and Q of a demodulating circuit 1A for orthogonally detecting a received signal obtained by time-multiplexing digital signals by BPSK, QPSK, and 8PSK modulation. A pattern regeneration circuit 40 outputs the same PN code pattern as on a transmission side. Inverting circuits 13 and 14 output I, Q as RI, RQ for a bit ‘0’ of a PN code pattern, and −I, −Q as RI, RQ for a bit ‘1’. A phase error table 15A contains a phase error between the phase of a received signal point as an output of the inverting circuits 13 and 14 and an absolute phase only for a first quadrant of RI, RQ. A phase error detecting processing circuit 16A reads the phase error data corresponding to the absolute value of RI, RQ, and adjusts the data into the data depending on the current quadrant of the RI, RQ.

Abstract: Information is recovered from a composite signal including first and second component signals modulated according to respective first and second modulations, for example, 8-PSK and GMSK. The composite signal is processed based on predetermined characteristics of the first and second modulations, for example, signal rotations, to generate a channel model for the first component signal and a whitening filter for the second component signal. The composite signal is filtered according to the whitening filter to generate a filtered signal. A symbol hypothesis for a symbol of the first component signal is evaluated using a metric with respect to the filtered signal that is a function of the whitening filter and the channel model, for example, in a multidimensional Viterbi symbol estimation algorithm. The invention may be embodied as methods, apparatus and computer program products.

Abstract: The base band signal processing circuit of the present invention intends to improve both the noise characteristic and the distortion characteristic, and moreover set both the characteristics in a desirable balance. The base band signal processing circuit is configured as follows: the first active low-pass filter and the second active low-pass filter are each formed in the balanced type, the first D/A converter differentially outputs the first base band signals and differentially inputs them to the first active low-pass filter, the second D/A converter differentially outputs the second base band signals and differentially inputs them to the second active low-pass filter, the first active low-pass filter differentially outputs the first base band signals, and the second active low-pass filter differentially outputs the second base band signals.

Abstract: An error correction technique for data communication receivers such as WLAN (Wireless Local Area Network) receivers is provided. The error correction technique is for correcting a frequency and/or phase error in an incoming digitally modulated signal. A constellation manipulator is provided that is adapted to manipulate the phase constellation system of the incoming digitally modulated system by mapping each constellation point of the phase constellation system to a predefined range of phase angles. The predefined range has a width of less than 2&pgr;. Further, an error detector is provided that is connected to receive data from the constellation manipulator. The data pertain to the manipulated phase constellation system. The error detector is adapted to evaluate the data to detect the frequency and/or phase error.

Abstract: A method of and apparatus for adapting an antenna array for closed loop transmit diversity, the method comprising: receiving an adapting signal corresponding to an antenna array weighting pattern for a time period; demodulating the adapting signal to provide a symbol for the time period; determining a preferred symbol from the symbol for the time period and a previous symbol for a previous time period; and transmitting with an antenna array weighting pattern corresponding to the preferred symbol.

Abstract: A coherent MASK-OFDM digital communication system that includes logics for modulating and demodulating digital signals to be communicated using M-ary amplitude shift keying (MASK) and orthogonal frequency division multiplexing (OFDM) is provided. This MASK-OFDM system can be implemented digitally by discrete cosine transform (DCT) and inverse discrete cosine transform (IDCT). The (I)DCT can be implemented, for example, by an (I)FCT.

Abstract: Variable code rate and signal constellation turbo trellis coded modulation (TTCM) codec. A common trellis is employed at both ends of a communication system (in an encoder and decoder) to code and decode data at different rates. The encoding employs a single TTCM encoder whose output bits may be selectively punctured to support multiple modulations (constellations and mappings) according to a rate control sequence. A single TTCM decoder is operable to decode each of the various rates at which the data is encoded by the TTCM encoder. The rate control sequence may include a number of rate controls arranged in a period that is repeated during encoding and decoding. Either one or both of the encoder and decoder may adaptively select a new rate control sequence based on operating conditions of the communication system, such as a change in signal to noise ratio (SNR).

Abstract: A new class of 16-ary Amplitude and Phase Shift Keying (APSK) coded modulations, called double-ring APSK modulation, based on an amplitude and phase shift keying constellation in which the locations of the digital signals to be encoded are placed on two concentric rings of equally spaced signal points. The APSK constellation parameters are optimised so as to pre-compensate the impact of non-linearities. The new modulation scheme is suited for being used with different coding schemes. It is shown that, for the same coding scheme, pre-distorted double-ring APSK modulation significantly outperforms classical 16-QAM and 16-PSK over a typical satellite channel, due to its intrinsic robustness against the high power amplifier non-linear characteristics. The proposed coded modulation scheme is shown to provide a considerable performance advantage for future satellite multi-media and broadcasting systems.

Abstract: The invention relates to a data transmission method and radio system. In particular, the invention relates to a method and system in which both the GMSK and the m-PSK modulation methods are available for the signal to be transmitted an in which the modulation method used at a given time can be changed to another modulation method. In the solution of the invention, the m-PSK modulator of the transmitter includes a multiplier adapted to multiply the signal to be transmitted by a given coefficient making the signal constellations of the received signal similar regardless of the modulation method. Thus, the processing of the signal in the receiver becomes easier and the quality of the transmission improves in connection with m-PSK modulation.

Abstract: A binary phase shift key demodulator (64) demodulates a signal conveying bits. A vector computation component (88) computes an I, Q vector associated with a reference bit and computes an I, Q vector associated with a subsequent bit. A vector comparison component (92) interprets the subsequent bit as a first binary value if the vector associated with the subsequent bit is within a first range of vector angles from the vector associated with the reference bit, and interprets the subsequent bit as a second binary value if the vector associated with the subsequent bit is outside of a second range of vector angles from the vector associated with the reference bit.

Abstract: A data transmission includes a sequence of information symbols followed by zero or more non-information symbols, which carry no power. A receiver determines the size of a data block, i.e., the number of information symbols in the transmission, by calculating a series of transition indicators. Each transition indicator represents a likelihood that a particular symbol position corresponds to a transition between the information symbols and non-information symbols of the transmission.