In an embodiment, a receiver detects a timing error between a transmitter clock at a transmitter and a receiver clock at a receiver associated with an exchange of CPM signals. The receiver phase aligns input samples of a candidate received signal over a time window based on a rotating signal corresponding to a phase progression of the candidate received signal. The receiver generates first and second partial sums of the phase-aligned input samples that are accumulations of phase-aligned input samples corresponding to modulation symbols that contribute positive and negative phases, respectively, to the phase progression. The receiver determines a phase difference between the first and second partial sums, and generates a timing-error metric that is indicative of a timing error between the transmitter clock and the receiver clock based at least in part upon the determined phase difference.

A method may include providing one or more telemetry transmission systems, the one or more transmission systems comprising one or more receivers and one or more transmitters. The method may also include transmitting a first synchronization sequence from the one or more telemetry transmission systems, the first synchronization sequence transmitted in a first channel, and the first synchronization sequence being at least a portion of a first telemetry signal. In addition, the method may include transmitting a second synchronization sequence the one or more telemetry transmission systems, the second synchronization sequence transmitted in a second channel, and the second synchronization sequence being at least a portion of a second telemetry signal. The first and second synchronization sequences may be transmitted simultaneously or at a predetermined time difference. The method may include receiving the first synchronization sequence at the one or more receivers, and receiving the second synchronization sequence at the one or more receivers.

A clock data recovery circuit includes a deglitch filter circuit and a timer circuit. The deglitch filter circuit is configured to remove pulses of less than a particular duration from a data signal to produce a deglitched data signal. The timer circuit is coupled to the deglitch filter, and is configured to compare a duration of a pulse of the deglitched data signal to a threshold duration, and identify the pulse as representing a logic one based on the duration of the pulse exceeding the threshold duration.

The present invention concerns a method for correcting a frequency shift on symbols received by a receiver, each symbol being composed of N samples and of a cyclic prefix of a predetermined number Δ samples, the Δ samples being a copy of Δ samples of the N samples. The receiver: —calculates for each symbol, a correlation between at most the Δ samples of the cyclic prefix and the at most Δ samples among the last samples, —averages the correlations over a number of symbols and determines one smooth frequency shift estimation for each averaged correlation, —calculates an exponential from the smooth frequency shift estimation, delays the received symbols by a delay, —multiplies the exponential by the delayed received symbols.

Disclosed embodiments relate, generally, to improved data reception handling at a physical layer. Some embodiments relate to end of line systems that include legacy media access control (MAC) devices and PHY devices that implement improved data reception handling disclosed herein. The improved data reception handling improves the operation of legacy systems, and the MAC more specifically, and in some cases to comply with media access tuning protocols implemented at the physical layer.

One embodiment of the present invention provides a system for facilitating synchronization of MAC addresses in a fabric switch. During operation, the system divides a number of media access control (MAC) addresses associated with devices coupled to an interface of the switch. The system then computes a checksum for a respective chunk of MAC addresses. In addition, the system broadcasts MAC address information of the chunk to facilitate MAC address synchronization in a fabric switch of which the switch is a member, and to manage the chunks and their corresponding checksum, thereby correcting an unsynchronized or race condition in the fabric switch.

A communication device includes: a plurality of sensors, each of which includes at least one sensor element that detects information relating to a single detection target and an output circuit that generates an output signal based on a detection signal of the sensor element and transmits the output signal; and a controller that acquires the output signal. One of the sensors transmits the output signal to the controller at an output timing that is shifted, by a predetermined period shorter than a length of one period of the output signal, from another output timing when another one of the sensors transmits the output signal.

Systems and methods for reducing total skew in optical signals transmitted by optical coherent transponders without measuring the total skew are disclosed. The method may compensate for the in-phase/quadrature (I/Q) skew of optical signals in complex modulation formats. It may include providing input to a transponder to produce a periodic (and generally sinusoidal) output signal, providing the signal to an optical power meter, measuring the optical power of positive and negative harmonics of the signal while varying the amount of skew introduced by a de-skewing filter in the transponder, identifying the amount of skew introduced by the de-skewing filter when the minimum optical power measurement is taken, and causing the amount of skew introduced by the de-skewing filter to equal the identified skew offset by a one-half symbol delay. The system may provide better skew compensation using less expensive equipment than de-skewing methods based on existing skew measurement methods.

Embodiments of this disclosure provide an apparatus and method for generating a transmitting sequence, a training sequence synchronization apparatus and method, an apparatus and method for estimating channel spacing and a system. The training sequence synchronization apparatus includes: a delay correlation processing unit configured to parallelly perform autocorrelation operations of different delay amounts on a receiving sequence containing a periodic training sequence to obtain multiple parallel correlation sequences; a superimposition processing unit configured to perform a superimposition operation on the multiple parallel correlation sequences to obtain a synchronization correlation sequence; and a synchronization extracting unit configured to perform a synchronization position extraction on the synchronization correlation sequence to obtain a synchronization position of the training sequence. With the embodiments of this disclosure, anti-noise performance of the training sequence may be enhanced.

Methods and apparatus for generating a standard pattern for data signals from a set of multiple data signals are provided. The standard pattern consists of a signal length, a centerline, an upper limit, and a lower limit. One of methods comprises, receiving first and second data signals, determining a standard pattern length for each of the first and second data signals, sampling each of the first and second data signals by as much as the determined standard pattern length, aligning the sampled first and second data signals, and generating a standard pattern for the first and second data signals by overlapping the aligned first and second data signals, wherein the generated standard pattern is a standard pattern having reflected thereinto upper and lower limit ranges that are determined using levels of the aligned first and second data signals.