Techniques, methods and system, for synchronization of sparse data signals are disclosed, comprising mixing a serial stream of sparse data signals with a serial stream of synchronization signals, to thereby add redundancy to the serial stream of sparse data signals and enable clock regeneration from a serial stream of mixed signals produced by said mixing, emulating the serial stream of synchronization signals by applying the clock regeneration to the serial stream of mixed signals, and generating a stream of parallel synchronization signals having a frequency of the serial stream of synchronization signals, deserializing the serial stream of mixed signals into a stream of parallel mixed signals having a data rate lower than a data rate of the serial signal streams, and demixing the stream of parallel synchronization signals with the stream of parallel mixed signals and thereby removing the redundancy introduced by the mixing into the sparse data signals and generating a parallel stream of demixed signals substantially synchronized with said synchronization signals.

A clock and data recovery (CDR) system includes a correlator configured to receive data, determine a first value of the received data, and output a second value corresponding to the received data, an accumulator configured to generate an accumulation value by accumulating the second value output from the correlator and output the accumulation value, and a state machine configured to determine whether a repeating pattern is present in the CDR system based on the accumulation value.

A communication link initialization method includes that a master node sends a first information frame to a slave node. The first information frame includes first synchronization information. The slave node implements synchronization with the master node based on the first synchronization information. The slave node sends a second information frame to the master node. The second information frame includes second synchronization information. The master node implements synchronization with the slave node based on the second synchronization information. The master node sends a third information frame to the slave node. The third information frame is used to indicate a first training information frame. The slave node trains a link between the master node and the slave node based on the third information frame. The slave node sends a fourth information frame to the master node.

A second device receives a first synchronization signal transmitted by a first device for training synchronization between the second device and the first device. The second device then transmits one or more initial synchronization response signals to the first device. The one or more initial synchronization response signals are from among a fixed number of synchronization response signals that the second device is configured to transmit to the first device. After transmission of the one or more initial synchronization response signals, the second device receives a second synchronization signal from the first device. After receiving the second synchronization signal, the second device continues transmission of synchronization response signals to the first device until the fixed number of synchronization response signals are transmitted from the second device to the first device.

A method and system that provides for execution of a first calibration sequence, such as upon initialization of a system, to establish an operation value, which utilizes an algorithm intended to be exhaustive, and executing a second calibration sequence from time to time, to measure drift in the parameter, and to update the operation value in response to the measured drift. The second calibration sequence utilizes less resources of the communication channel than does the first calibration sequence. In one embodiment, the first calibration sequence for measurement and convergence on the operation value utilizes long calibration patterns, such as codes that are greater than 30 bytes, or pseudorandom bit sequences having lengths of 2.sup.N−1 bits, where N is equal to or greater than 7, while the second calibration sequence utilizes short calibration patterns, such as fixed codes less than 16 bytes, and for example as short as 2 bytes long.

Systems, apparatuses, and methods for utilizing training sequences on a replica lane are described. A transmitter is coupled to a receiver via a communication channel with a plurality of lanes. One of the lanes is a replica lane used for tracking the drift in the optimal sampling point due to temperature variations, power supply variations, or other factors. While data is sent on the data lanes, test patterns are sent on the replica lane to determine if the optimal sampling point for the replica lane has drifted since a previous test. If the optimal sampling point has drifted for the replica lane, adjustments are made to the sampling point of the replica lane and to the sampling points of the data lanes.

Systems, apparatuses, and methods for implementing asynchronous feedback training sequences are described. A transmitter transmits a training sequence indication to a receiver via a communication channel including a plurality of data lines. The training sequence indication includes a bit sequence to indicate the beginning of a training sequence. The indication includes a transition from a zero to a one at the midpoint of a supercycle of ‘N’ clock cycles in length, followed by a predetermined number of ones. The training sequence indication is then followed by a test pattern. The beginning of the test pattern occurs at the end of a supercycle. The receiver determines if there are any errors in the received test pattern, and then sends feedback to the transmitter that indicates whether any errors were detected. Responsive to receiving the feedback, the transmitter alters delay settings for one or more of the data lines.

A processing module for a receiver device. The processor module comprises a channel estimate generation component arranged to output channel estimate information for a received signal, and a timestamping module arranged to determine a ToA measurement for a marker within a packet of the received signal based at least partly on the channel estimate information for the received signal generated by the channel estimate generation component. The channel estimate generation component comprises a validation component arranged to derive a validation pattern for the packet within the received signal for which a ToA measurement is to be determined, identify a section of the packet containing a validation sequence, and perform cross-correlation between at least a part of the validation sequence within the packet and at least a part of the generated validation pattern to generate channel estimate validation information.

A method and system that provides for execution of a first calibration sequence, such as upon initialization of a system, to establish an operation value, which utilizes an algorithm intended to be exhaustive, and executing a second calibration sequence from time to time, to measure drift in the parameter, and to update the operation value in response to the measured drift. The second calibration sequence utilizes less resources of the communication channel than does the first calibration sequence. In one embodiment, the first calibration sequence for measurement and convergence on the operation value utilizes long calibration patterns, such as codes that are greater than 30 bytes, or pseudorandom bit sequences having lengths of 2.sup.N−1 bits, where N is equal to or greater than 7, while the second calibration sequence utilizes short calibration patterns, such as fixed codes less than 16 bytes, and for example as short as 2 bytes long.

Advanced detectors for vector signaling codes are disclosed which utilize multi-input comparators, generalized on-level slicing, reference generation based on maximum swing, and reference generation based on recent values. Vector signaling codes communicate information as groups of symbols which, when transmitted over multiple communications channels, may be received as mixed sets of symbols from different transmission groups due to propagation time variations between channels. Systems and methods are disclosed which compensate receivers and transmitters for these effects and/or utilize codes having increased immunity to such variations, and circuits are described that efficiently implement their component functions.