Provided is a technique that can generate a spread spectrum clock signal in all of an upper-spread mode, a down-spread mode, and a center-spread mode. A spread spectrum clock generator (2) spreads a spectrum of a signal with a predetermined carrier frequency to generate a spread spectrum clock signal under the control of a control unit (13). The control unit includes carrier frequency correction control means (13b). The carrier frequency correction control means shifts the predetermined carrier frequency to generate, from one spread mode, a spread spectrum clock signal of another pseudo spread mode.

A method and a device are described for determining data from a signal spread over at least one frequency base band representing the data. The method for generating a signal has a step of using at least one highly auto-correlated spread code sequence (1C, 2C) associated with the frequency base band for determining a delay with which a modulated portion (1P, 2P) of the data is spread on the signal. The method has further steps of determining said modulated portion from the signal using the delay and the spread code sequence (1C, 2C), of demodulating the modulated portion (1P, 2P) using phase shift keying, and of determining a remainder (1R, 2R) of the data using the delay.

A code acquisition module for a direct sequence spread spectrum (DSSS) receiver includes: a Sparse Discrete Fourier transform (SDFT) module configured to perform an SDFT on a finite number of non-uniformly distributed frequencies comprising a preamble of a received DSSS frame to calculate Fourier coefficients for the finite number of non-uniformly distributed frequencies; a multiplier configured to multiply the Fourier coefficients for the finite number of non-uniformly distributed frequencies of the received DSSS frame by complex conjugate Fourier coefficients for the finite number of non-uniformly distributed frequencies to generate a cross-correlation of the received DSSS frame and the complex conjugate Fourier coefficients; and a filter module configured to input the cross-correlation and output a delay estimation for the received DSSS frame.

Circuits and methods for performing a clock and data recovery are disclosed. In one example, a circuit is disclosed. The circuit includes an FSM. The FSM includes: a first accumulator, a second accumulator, and a third accumulator. The first accumulator is configured to receive an input phase code representing a phase timing difference between a data signal and a clock signal at each FSM cycle, to accumulate input phase codes for different FSM cycles, and to generate a first order phase code at each FSM cycle. The second accumulator is coupled to the first accumulator and configured to accumulate the input phase codes and first order phase codes for different FSM cycles, and to generate a second order phase code at each FSM cycle. The third accumulator is coupled to the second accumulator and configured to accumulate the input phase codes and second order phase codes for different FSM cycles, and to generate a third order phase code at each FSM cycle.

A Pseudo-Random Noise code generator module is configured to generate PRN codes operating with different navigation standards for use with a GNSS receiver. The generator includes a number of linear shift registers including a respective number of feedback taps and a channel selection network including an output multiplexer. A first register includes a first number of taps and a second register includes a second number of taps. The first register and second register are associated with a respective feedback network to combine signals at the feedback taps to obtain a feedback signal that is selectably fed back through a selection circuit at an input of the respective register. A network can selectably concatenate the first register with the second register.

The present invention provides a circuitry including a PLL and a CDR circuit, wherein the CDR circuit includes a phase detector, a loop filter, a SSC demodulator, a control code generator and a phase interpolator. The PLL is configured to generate a clock signal with SSC modulation and a SSC direction signal. The phase detector is configured to compare phases of an input signal and an output clock signal to generate a detection result, wherein the input signal is with SSC modulation. The loop filter is configured to filter the detection result to generate a filtered signal. The SSC demodulator is configured to receive the SSC direction signal to generate a control signal. The control code generator is configured to generate a control code according to the filtered signal and the control signal to control the phase interpolator to use the clock signal to generate the output clock signal.

A modulation circuit includes a locked loop circuit with two-point modulation control and a phase-frequency detector configured to compare a reference frequency signal with a feedback frequency signal. A two-point modulation control circuit includes a first modulation path having a controllable gain and coupled to one of the first and second modulation control points and a second modulation path coupled to another of the first and second modulation control points. Gain matching of the first and second modulation paths is accomplished through the operation of a calibration circuit. The calibration circuit includes a phase detector circuit configured to compare the reference frequency signal with the feedback frequency signal to generate a phase detect signal, and a gain control circuit configured to adjust the controllable gain of the first modulation path as a function a correlation of the phase detect signal with signs of the modulation data.

Disclosed are methods and apparatus used in wireless communications. The methods and apparatus establish a codebook for use in sparse code multiple access (SCMA) encoded communications, in particular. The SCMA codebook is configured to set the codebook for at least one layer (i.e., a user) to include a constellation of points having a first grouping of constellation points located at first radial distance from an origin in a complex plane and a second grouping of constellation points located at a second radial distance from the origin. This codebook arrangement provides increased gains at receivers by optimizing the constellation shape to improve the distance between constellation points (i.e., SCMA codebook performance), and in particular more robust performance when encountering amplitude and phase misalignment in uplink (UL) multiple access.

Systems and methods for a communication system including a set of transmitters, wherein operations of the set of transmitters are synchronized with an accuracy bound by a synchronization error. A controller forms a message with ordered symbols including data symbols and at least one identification symbol, and controls transmitters from the set of transmitters to transmit the message using a cyclic delay diversity (CDD). Wherein each transmitting transmitter prior to transmitting, circularly rotates the ordered symbols of the message with a unique shift, then copies some symbols located at an end of the message. Wherein a number of the copied symbols is based on a predetermined cyclic prefix length, into a first position in the rotated message, to form a transmitter identifiable message, and transmits via each transmitting transmitter the transmitter identifiable message.

Circuits and methods for performing a clock and data recovery are disclosed. In one example, a clock and data recovery circuit is disclosed. The circuit includes a third order digital filter, e.g. a finite state machine (FSM) that includes three accumulators connected in series. Among the three accumulators, a first accumulator receives an input phase code representing a phase timing difference between a data signal and a clock signal at each FSM cycle and accumulates input phase codes for different FSM cycles to generate a first order phase code at each FSM cycle; a second accumulator accumulates the input phase codes and first order phase codes for different FSM cycles to generate a second order phase code at each FSM cycle; and a third accumulator accumulates the input phase codes and second order phase codes for different FSM cycles to generate a third order phase code at each FSM cycle.