Abstract: Disclosed are a code modulation method and apparatus for high order modulation. The method comprises: converting information that needs to be transmitted into a bit data stream, and demultiplexing the bit data stream into more than one channel of bit data stream; performing first-type coding on at least one channel of bit data stream in the more than one channel of stream, to obtain first output data; performing second-type coding on at least one channel of the remaining channels of bit data stream on which the first-type coding is not performed, to obtain second output data; and performing quadrature amplitude modulation on the first output data, to generate a modulation symbol for output. Compared with the prior art, the correctness rate of demodulation in the technical solution is improved significantly, achieving higher transmission efficiency.

Abstract: A method for optimising a coded modulation scheme with a given spectral efficiency for communication over a fading channel represented/identified by B fading gains, where B is an integer number expressing the ratio between a code word duration and the duration over which the fading remains constant. The fading gains belong to a B-dimensional space of fading gains.

Abstract: A projection code is applied to encode symbols as weighted arithmetic sums of approximately random subsets of binary source bits. Pairs of the symbols are combined to form constellation points, which are sequentially mapped through a constellation to modulate a data signal.

Abstract: A method includes detecting one or more of an upward transition of a single-ended data signal via a first driver path to a pre-emphasis transmitter or a downward transition of the single-ended data signal via a second driver path to the pre-emphasis transmitter. The method also includes generating a pre-emphasis pulse at the pre-emphasis transmitter in response to detecting the upward transition or the downward transition of the single-ended data signal.

Abstract: A wireless local area network (WLAN) transmitter includes a baseband processing module and a plurality of radio frequency (RF) transmitters. The processing module selects one of a plurality of modes of operation based on a mode selection signal. The processing module determines a number of transmit streams based on the mode selection signal. The processing of the data further continues by converting encoded data into streams of symbols in accordance with the number of transmit streams and the mode selection signal. A number of the plurality of RF transmitters are enabled based on the mode selection signal to convert a corresponding one of the streams of symbols into a corresponding RF signal such that a corresponding number of RF signals is produced.

Abstract: A method and transmitter and receiver for determining and transmitting or receiving a non-uniform QAM signal comprises selecting a signal to noise ratio for a channel and forward error corrector and then determining positions of constellation points that maximise a measure of channel capacity at the selected signal to noise ratio. The position of one constellation point and another constellation point within the constellation are constrained to be equal to one another prior to determining the positions of the constellation points. In doing so, a so called condensed QAM constellation arrangement may be derived having fewer than conventional number of constellation points for a given QAM scheme. The condensed QAM arrangement has improved performance at certain signal to noise ratios.

Abstract: A method for data transmission using spatial-domain modulation, and a transmitter using the same has been proposed. The method comprises the following steps including at least but not limited to receiving a plurality of symbols to be transmitted, mapping the symbols as L-dimensional coordinate, wherein 1<L<N, dividing the antennas into L non-overlapping antenna groups, choosing one activating antenna from the antennas in each of the antenna groups according to the coordinate of the symbols, and transmitting modulated signal by using the activating antenna in each of the antenna groups.

Abstract: A Digital-to-Time (DTC) for a Digital Polar Transmitter (DPT) comprises a coarse delay/phase segment and a fine delay/phase segment. The coarse delay/phase segment generates an even delay/phase signal and an odd delay/phase signal. The fine/phase delay segment receives the even coarse phase signal and the odd coarse phase signal, and is responsive to a fine delay/phase control signal to generate a fine delay/phase output signal that is an interpolation of the even delay/phase signal and the odd delay/phase signal. In one exemplary embodiment, the fine delay/phase control signal comprises a binary signal having 2N values, and the fine delay/phase segment comprises 2N interpolators. Each interpolator is coupled to the even and odd coarse phase signals and is controlled by the fine delay/phase control signal to be responsive to the even coarse phase signal or the odd coarse phase signal based on a value of the fine delay/phase control signal.

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: The present invention employs hierarchical modulation to simultaneously transmit information on different modulation layers using a carrier RF signal. Initially, first data to be transmitted is assigned to a first modulation layer and second data is assigned to a second modulation layer. In one embodiment of the present invention, the first and second data are assigned based on reliability criteria. The first and second modulation layers are hierarchical modulation layers of the carrier RF signal. Once assigned, the first data is transmitted using the first modulation layer of the carrier RF signal and the second data is transmitted using the second modulation layer of the carrier RF signal. In one embodiment of the present invention, information may be transmitted to one end user using one modulation layer, and information may be transmitted to a different end user using a different modulation layer.

Abstract: Provided is a relay node that performs network coding with respect to signals transmitted from a plurality of sources. The relay node may partition a plurality of constellation points into a plurality of subsets, generate a new constellation diagram based on respective characteristics among the plurality of subsets, and perform network coding based on the new constellation diagram.

Abstract: An antenna modulation method applicable to a transmitter comprising a processing unit which is configured to execute functions including at least but not limited to receiving a symbol represented by a bit stream; converting the bit stream into a coordinate point of a signal constellation comprising a horizontal-axis component and a vertical-axis component; converting, from the horizontal-axis component of the coordinate point, a first vector having at least a first entry and a second entry; converting, from the vertical-axis component of the coordinate point, a second vector having at least a third entry and a fourth entry; generating a third vector having at least a fifth entry and a sixth entry by summing the first vector and the second vector; and activating at least one of the first antenna and the second antennas based on one or more non-zero entries of the third vector.

Abstract: A system may comprise a symbol mapper circuit that outputs C? quadrature amplitude modulation (QAM) symbols per orthogonal frequency division multiplexing (OFDM) symbol. The system may also comprise circuitry operable to process said C? QAM symbols using a circulant matrix to generate a particular OFDM symbol consisting of C+? subcarriers, where C? is a first integer, C is a second integer less than C?, and ? is an integer equal to the number of non-data-carrying subcarriers in the particular OFDM symbol. The circulant matrix may be a P×P matrix, where P is an integer less than C?. The system may comprise a nonlinear circuit that introduces nonlinear distortion to said particular OFDM symbol.

Abstract: A communications transmitter includes a baseband processor configured to generate amplitude, angle, in-phase and quadrature baseband signals and a combination modulator that is configurable to modulate in the polar domain and, alternatively, in the quadrature domain. The combination modulator includes a quadrature modulator and a separate and distinct angle modulator that is configured to serve as a local oscillator for the quadrature modulator. In one embodiment of the invention the combination modulator is configured to modulate in the quadrature domain when the transmitter is operating according to a first communications condition (e.g., first transmit power level or first modulation scheme) and is configured to modulate in the polar domain when the transmitter is operating according to a second communications condition (e.g., second transmit power level or second modulation scheme).

Abstract: A transmitter apparatus wherein a simple structure is used to successfully suppress the degradation of error rate performance that otherwise would be caused by fading or the like. There are included encoding parts that encode transport data; a mapping part that performs such a mapping that encoded data sequentially formed by the encoding parts are not successively included in the same symbol, thereby forming data symbols; and a symbol interleaver that interleaves the data symbols. In this way, a low computational complexity can be used to perform an interleaving process equivalent to a bit interleaving process to effectively improve the reception quality at a receiving end.

Abstract: A dual rate transmitter may include a modulator circuit configured to modulate orthogonal signals to generate a quadrature modulated signal. An amplifier may be configured to amplify the quadrature modulated signal to produce an amplified signal. A quadrature partial response (QPR) filter may be configured to process the amplified signal to generate an output signal. The QPR filter may allow for full rate QPR and half rate QPSK operation of the transmitter device. The output signal may be transmitted via an antenna. This transmitter approach provides a bandwidth efficiency improvement, as the QPR signal may be operated at twice the rate within the same bandwidth as the quadrature modulated signal using a common saturated transmitter implementation, reducing quantity of components and the resulting mass and cost reduction for a space transmitter solution. Additionally, this approach of using QPR signaling provides greater power efficiency.

Abstract: A system and method including a parity bit encoder for encoding each n bits of data to be transmitted with a parity check bit to produce blocks of n+1 bits (n information bits plus one parity bit associated with the n information bits). Each of the blocks of n+1 bits are Gray mapped to a plurality of associated QAM symbols that are modulated onto an optical wavelength and transmitted to a receiver. A maximum a posteriori (MAP) decoder is used at the receiver to correct for cycle slip. Phase errors of 180 degrees may be detected by independently encoding odd and even bits prior to Gray mapping, and identifying errors in decoding odd numbered bits at the receiver.

Abstract: A method and an apparatus for modifying a complex-valued signal are described, the complex-valued signal representing a first symbol and a second symbol. A signal trajectory of the complex-valued signal between the first and second symbols is determined, and, if the signal trajectory passes nearby the constellation origin, the signal trajectory is altered to run closer to the constellation origin.

Abstract: A modulator (100) comprises a polar generation stage (120) arranged for generating an amplitude component and a phase component of a modulation signal, a differentiator stage (150) arranged for generating a differentiated phase component by differentiating the phase component; and an event detection stage (170) arranged for detecting a high bandwidth event by detecting at least one of the amplitude component and the differentiated phase component meeting an event criterion. An inversion stage (130) is arranged for generating a modified amplitude component by inverting the amplitude component in response to detecting the high bandwidth event. A phase offset stage (150) is arranged for generating a modified differentiated phase component by, in response to detecting the high bandwidth event, adding to the differentiated phase component a phase offset having a magnitude of 180 degrees and a sign opposite to a sign of the differentiated phase component.

Abstract: A method of transmitting a broadcasting signal is provided. The method includes encoding data; encoding signaling data by an LDPC (Low Density Parity Check) scheme; building a signal frame based on at least one preamble data symbol having the encoded signaling data and a data slice having the encoded data; inserting at least one pilot into the signal frame with a specific pattern and modulating the signal frame by an OFDM (Orthogonal Frequency Division Multiplexing) method; and transmitting the modulated signal frame. A signaling block having the signaling data is repeated in the at least one preamble data symbol in a frequency domain by a bandwidth. The bandwidth of the signaling block corresponds to a number of active subcarriers assigned to a single channel.

Abstract: Embodiments of this invention describe a method to reduce the effective inter carrier spacing between the sub-carriers of wireless, wired or optical transmissions and thereby increase the spectral efficiency of the communication system. Signal transmitted from multiple transmit chains are shifted in frequency at the transmitter. At the receiver a plurality of receive chains is used, the received signals are similarly shifted in frequency and used to reduce the inter carrier interference. Embodiments also describe a method for Full Duplex communication where the transmitters transmit using different frequency shifts. The receiver receives the transmitted signal and an echo of it's transmission. As the received transmission is shifted in frequency from it's transmission, it can cancel out the echo and receive the intended signal.

Abstract: Methods and systems for communicating are disclosed. A method includes obtaining input communication symbols selected from a set of communication symbols, converting input communication symbols into transmittable waveforms using non-periodic functions, and transmitting transmittable waveforms over a communication channel. Another method includes receiving transmittable waveforms constructed using non-periodic functions and transmitted over a communication channel, and demodulating transmittable waveforms. A system includes a modulator adapted to obtain input communication symbols selected from a set of communication symbols and adapted to convert input communication symbols into transmittable waveforms using non-periodic functions, and a transmitter or transceiver adapted to transmit transmittable waveforms over a communication channel.

Abstract: A direct conversion transmitter has a mixer stage to up-convert an input signal to the frequency of a local oscillator (LO). A DC offset circuit is coupled to an input signal port to apply a set of DC offset signal values. A processor determines a set of optimal DC offset signal values by no more than three differential spectral measurements made at the transmitter output port with a test signal applied at the input port. Optimal DC offset signal values are those that, when applied to the input signal at the input port of the transmitter, minimize an LO leakage component of the transmit signal at the output signal port of the transmitter. The optimal DC offset values are stored in memory and retrieved and applied to information bearing signals provided as the input signal once those optimal DC offset values have been determined.

Abstract: Systems and methods of performing ASK or QAM modulation with uneven distance between symbols are provided. Different bit positions mapped to such symbols are assigned to different receivers, with the result that there are different BER performances among bits sent from a transmitter to the different receivers. Bits for multiple receivers are mapped to a UASK constellation or a UQAM constellation without using superposition.

Abstract: Embodiments of a system and method for providing fundamental group modulation are generally described herein. In some embodiments, a trajectory mapper is arranged to receive a modulation symbol sequence. A signal trajectory sample memory is arranged to store a representation of signal trajectories for a topological space having a set of predetermined removed regions therein. The trajectory mapper accesses the signal trajectory sample memory to select a signal trajectory relative to the set of predetermined removed regions in the topological space based on the received modulation symbol sequence and produces a sequence of in-phase (I) and quadrature (Q) sample values at a specified sample rate in response to the selected signal trajectory, the I and Q sample values serving as a basis for an amplified radio frequency signal.

Abstract: Array amplitude modulation which includes mapping a data symbol to a phase modulation signal and an amplitude modulation signal for transmission from antenna elements; applying the phase modulation signal to the antenna element amplifiers; and generating a pattern of enabling/disabling the antenna element amplifiers as a function of the amplitude modulation to produce a phase and amplitude modulated transmission from the antenna elements.

Abstract: Systems and methods are disclosed for providing sales or customer support using a telephone having a camera to capture at least a partial image of a product or service; wherein the at least partial image is used to select a database updated by one or more knowledgeable persons on the product or service.

Abstract: A low latency transmitter and receiver for an OFDM system are disclosed. The low latency transmitter includes an FFT module and a baseband modulator. The FFT module computes IDFT of PSK constellation data symbols or QAM constellation data symbols. The baseband modulator performs complex modulation of the IDFT samples by multiplying these samples with 1 and ?1 alternatively in time domain. The low latency receiver includes a baseband demodulator and another FFT module. The baseband demodulator performs complex demodulation of the received samples of OFDM symbols by multiplying the samples of OFDM symbols with 1 and ?1 alternatively in time domain thereby obtaining baseband demodulated symbols. The FFT module of the receiver computes DFT of samples of the baseband demodulated symbols to obtain samples of the OFDM demodulated symbols.

Abstract: A method is provided for modulating a real data stream grouped into blocks of nb.M real data, where M is the number of carriers and nb is an integer greater than or equal to 2. The method includes, for a block of real data: a first modulation by a first modulator of the first M/2 data, delivering a first set of modulated carriers; a second modulation by a second modulator of the following (nb?1).M data, delivering a second set of (nb?1).M modulated carriers; a third modulation by a third modulator of the last M/2 data, delivering a third set of modulated carriers; and a superposition of the first, second and third sets, forming a block of OFDM/OQAM symbols of length nb.M/2, the first set being superposed with the start of the second set and the third set being superposed with the end of the second set.

Abstract: A method for calibrating a channel which includes: performing slide-window correlation on a delayed downlink service signal of a current transmit channel and a feedback signal of the transmit channel, and performing sampling to obtain a group of correlation values of the transmit channel in a sliding window; determining a peak amplitude value among amplitude values of the group of correlation values in the sliding window, and amplitude values at two points that are left adjacent and right adjacent to a point corresponding to the peak amplitude value; performing an interpolation operation on the peak amplitude value and the amplitude values at the two points that are left adjacent and right adjacent to the point to obtain an amplitude value, a delay and a phase at an actual peak point in the group of correlation values of the transmit channel in the sliding window; and calibrating the transmit channel.

Abstract: A transmitter comprises a baseband signal path, which is designed to provide a first baseband signal having an in-phase component and a quadrature component in a first mode of the transmitter and to provide a second baseband signal having an amplitude component and a phase component in a second mode of the transmitter; an oscillator circuit, which is designed to provide an oscillator signal, wherein the oscillator circuit is furthermore designed to provide the oscillator signal as an unmodulated signal in the first mode and to provide the oscillator signal as a modulated signal in the second mode, wherein a modulation of the oscillator signal in the second mode is based on the phase component of the second baseband signal; and a radio-frequency digital-to-analogue converter (RF-DAC), which is designed to receive the oscillator signal, the first baseband signal and the amplitude component of the second baseband signal, wherein the RF-DAC is furthermore designed to provide the vector-modulated RF output signal

Abstract: The present invention provides a data transmission device and method in a wireless communication system. The device comprises a processor which is connected with the M antennas and which is formed so as to generate data to be transmitted through the M antennas, on the basis of a precoding matrix; the precoding matrix is generated based on a plurality of matrices; and a first matrix, which is one matrix among the plurality of matrices, is selected from within a codebook for N antennas (where N<M).

Abstract: Techniques for transmitting information in a wireless network are described. In an aspect, information may be conveyed based on specific resources used to send a signal, e.g., a pilot. A pseudo-random function may receive the information to convey via the signal and possibly other information and may provide pseudo-random values, which may be used to select the resources to use to send the signal. In one design, a transmitter (e.g., a base station for a sector) may determine first information (e.g., a sector ID) to convey via a pilot and may also determine second information for absolute time (e.g. a pilot cycle index). The transmitter may determine resources (e.g., slots) to use to send the pilot based on the first and second information and possibly based further on a PN offset assigned to the sector. The transmitter may transmit the pilot in the determined resources.

Abstract: A transmission arrangement for modulating useful signals onto a carrier frequency signal has a frequency generator for generating the carrier frequency signal, a first modulation path for modulating a first useful signal onto the carrier frequency signal, and a second modulation path for modulating a second useful signal onto the carrier frequency signal. The first modulation path has a digital modulator for providing an amplitude signal and a Cartesian signal pair from the first useful signal and a Cartesian modulator for modulating the Cartesian signal pair onto the carrier frequency signal in order to provide an intermediate signal. The first modulation path is configured in such a manner that the amplitude signal is modulated onto the intermediate signal in order to provide an output signal.

Abstract: A modulator generates a baseband digital signal from an information-bearing digital signal. The baseband signal has time-varying phase and amplitude defined by a sequence of complex data words, each having an in-phase (I) component and a quadrature (Q) component. A noise-shaping modulator generates a noise-shaped digital signal from the baseband digital signal such that quantization noise in the noise-shaping modulator is attenuated by a spectral null of its noise transfer function. The spectral null is selected by a noise-shaping parameter corresponding to a selected one of a plurality of output frequencies. A signal converter generates an analog signal conveying the information of the information-bearing digital signal on an analog carrier signal having the selected output frequency.

Abstract: A pre-distortion circuit that may introduce a pre-distortion signal in a communication channel by determining a harmonic signal of the signal to be output. One or more image correction signals of the signal to be output may be determined. The one or more image correction signals may be complex conjugate signal variations of the signal to be output. The harmonic signal, the one or more image correction signals and the signal to be output may be combined into a combined output signal. The combined output signal may be transmitted to a digital-to-analog converter. The predistortion circuit may be implemented in a FPGA, an ASIC, a digital-to-analog converter, and/or a separate IC package.

Abstract: The present invention is directed to data communication system and methods. More specifically, various embodiments of the present invention provide a communication interface that is configured to transfer data at high bandwidth using nDSQ format(s) over optical communication networks. In certain embodiments, the communication interface is used by various devices, such as spine switches and leaf switches, within a spine-leaf network architecture, which allows large amount of data to be shared among servers.

Abstract: Embodiments of the present disclosure describe methods, apparatuses, and systems related to use of interphase/quadrature component layer shifting in open loop multiple-input, multiple-output communications. Other embodiments may be described and/or claimed.

Abstract: When a determination is made that communication by an SM scheme is suitable, a setting unit performs switching from a communication level by an STC scheme to the communication level by the SM scheme, between the communication level at a first level of MCS by the space-time coding scheme and the communication level at a second level of MCS by the SM scheme. When a determination is made that communication by the SM scheme is unsuitable, the setting unit performs switching from the communication level by the STC scheme to the communication level by the spatial multiplexing scheme, between the communication level at a third level of MCS, which is higher than the first level, by the space-time coding scheme and a fourth level of the modulation scheme and the coding rate, which is higher than the second level, by the SM scheme.

Abstract: A receiver, in particular a VAMOS receiver, is provided. The receiver is adapted to split the complex-valued baseband signal into its real and imaginary parts. The two branch system thus created is modeled as a real-valued Multiple Input Multiple Output, MIMO, system. The receiver is further adapted to use correlations of the noise, both in time and between branches of a channel to suppress the noise for multi-users in the same channel. In accordance with one embodiment the receiver is adapted to take into account the known symmetries present in a symbol constellation when more than one user exists in the same channel. This is for example the case in adaptive symbol constellation such as an adaptive alpha-QPSK constellation. Using the receiver in accordance with the above can provide the same performance as a joint detection receiver in the presence of Gaussian white noise, while giving better interference suppression than either SAIC or joint detection in the presence of GMSK modulated interference.

Abstract: Techniques for rotating and transmitting multidimensional constellations are disclosed. A method for rotating a multidimensional constellation may include constructing a first rotation matrix, constructing a second rotation matrix, applying orthogonality constraints to the first and second rotation matrices; selecting an optimizing rotation matrix from the first and second rotation matrices; and rotating the multidimensional constellation using the optimizing rotation matrix. Constructing the first rotation matrix and second rotation matrices may include constructing a first column that includes first matrix elements based on the number of axes in the multidimensional constellation, and additional columns that include permutations of the first matrix elements.

Abstract: A communications device includes a transmitter, a transmission processing device, a receiver, and a reception processing device. The transmission processing device assigns signal-space points within an I/Q signal space to digital signals, which include data values. The reception processing device assigns data values to signal-space points. The transmitter generates a transmission signal from signal-space points to be transmitted. The receiver determines received signal-space points from a received signal. The individual transmitted and received signal-space points provide in each case a smaller spacing distance from adjacent signal-space points than from the origin of the signal space.

Abstract: A transmission device of the present invention includes a baseband waveform generator to generate a transmission signal by using a transfer function H0(f) that is in a relation of a matched filter with a transfer function H1(f) in an analog domain of a transmission side and a reception side connected through a wireless channel, and transmits the transmission signal generated by the baseband waveform generator.

Abstract: One or more embodiments provides method for transmitting a signal by a transmitting apparatus in wireless a communication system supporting a modulation scheme based on a quadrature amplitude modulation (QAM) scheme and a frequency shift keying (FSK) scheme. The method includes determining at least one first bit which will be mapped to at least one QAM symbol and at least one second bit which will be mapped to at least one FSK symbol among bits included in an encoded input bit stream; and generating a modulation symbol by mapping the at least one first bit to the at least one QAM symbol and mapping the at least one second bit to the at least one FSK symbol based on a Hamming distance of the at least one second bit.

Abstract: Embodiments of a system and method for generating a shaped cyclic time-domain waveform are generally described herein. In some embodiments, a first transform may be performed on an input symbol vector to generate a transformed input vector in a transform domain. The transformed input symbol vector may be expanded to generate an expanded symbol vector. At least some elements of the expanded symbol vector may be weighted with a weighting vector selected for pulse shaping to generate a weighted symbol vector. A second transform may be performed on the weighted symbol vector to generate an output symbol vector for subsequent processing and transmission. The second transform may be an inverse of the first transform and may comprise a greater number of points than the first transform.

Abstract: A system is configured to receive a block of symbols, associated with a phase-modulated signal that includes data symbols that correspond to a payload associated with the signal, and control symbols; process the control symbols to identify an amount of phase noise associated with the control symbols; reset a phase, associated with each of the data symbols, based on the amount of phase noise and a reference phase; interleave the respective data samples, of each of the data symbols with other data samples, where the interleaved respective data samples cause errors, associated with the respective data samples, to be spread out among the other data samples and reduces an error rate relative to a prior data rate that existed before the interleaving; and perform forward error correction on the interleaved respective data samples.

Abstract: A method and an apparatus for mapping a quadrature amplitude modulation (QAM) symbol. The QAM symbol mapping apparatus includes a frequency checker, which checks frequencies of sub-carriers in an orthogonal frequency division multiplexing (OFDM) symbol; and a data categorizer, which maps data coded for error correction and uncoded data to the sub-carriers based on the checked frequencies, wherein the data categorizer maps a combination of the coded data and the uncoded data with respect to sub-carriers having frequencies lower than a reference frequency.

Abstract: A transmission apparatus includes: a multiplier configured to multiply a signal provided on a complex plane by a multiplication coefficient corresponding to a number of transmission sub-carriers; and an inverse fast Fourier transformer configured to perform an inverse fast Fourier transform on the multiplied signal.

Abstract: A method and a system for compensating a delay mismatch between a first measurement channel and a second measurement channel is disclosed. A method for compensating a delay mismatch between a first measurement channel and a second measurement channel includes providing a reference point for starting the first and second measurement channel, and starting the first measurement channel after expiration of a first delay period which begins at the reference point. The method further includes starting the second measurement channel after expiry of a second delay period which begins at the reference point, wherein a difference between a length of the first delay period and a length of the second delay period is substantially equal to the delay mismatch between the first measurement channel and the second measurement channel.

Abstract: Apparatus and methods are disclosed related to low-voltage radio transmitters with high spectral purity. One such apparatus includes a baseband path with a predistortion stage, a programmable filter, and an upconverter core. In an embodiment, the programmable filter is placed between the predistortion stage and the upconverter core. In an embodiment, the programmable filter is configured by a controller to reject out-of-band noise introduced at the predistortion stage or earlier.