Abstract: An illustrative SerDes (serializer-deserializer) communications method embodiment may include a transceiver: selecting one of multiple registers to specify initial pre-equalizer coefficient values; updating the initial pre-equalizer coefficient values during a training phase; and using the updated pre-equalizer coefficient values to convey a transmit data stream. In an illustrative embodiment of a chip-to-module communications link, a port connector couples a port transceiver to a pluggable module transceiver, the pluggable module transceiver including: one or more transmit filters to each pre-equalize a corresponding serial symbol stream being transmitted to the port transceiver; and a controller having multiple registers, each of the multiple registers containing a set of initial coefficient values, the controller using one of the registers to set initial coefficient values for the one or more transmit filters.

Abstract: Precompensator-based quantization techniques offer a way to reduce the complexity and power requirements of clock recovery modules while offering improved timing recovery performance relative to a bang-bang scheme operating in a lossy channel.

Abstract: A device includes a network interface that includes a physical coding sublayer (PCS) unit. The PCS unit receives an Ethernet packet. The PCS unit encode the Ethernet packet into a transmission frame that includes a first set of bit fields corresponding to contents of the Ethernet packet and a second set of bit fields corresponding to control information for the encoding. The PCS unit computes a validity value of the transmission frame, wherein the validity value is based on the first set of bit fields included in the transmission frame. The PCS unit inserts the validity value of the transmission frame into one or more idle bit fields in the second set of bit fields included in the transmission frame. The PCS unit processes the transmission frame for sending to a receiving device over a physical medium.

Abstract: An illustrative multi-lane communication method implements a hidden backchannel to communicate equalization information and/or other link-related data without impinging on the user bandwidth allocated by the relevant articles of IEEE Std 802.3.

Abstract: An illustrative multi-lane communication method implements a hidden backchannel to communicate equalization information and/or other link-related data without impinging on the user bandwidth allocated by the relevant articles of IEEE Std 802.3.

Abstract: Various aspects of this disclosure describe detecting a signal and measuring power with a multi-band filter. Examples include a signal detection and power measurement module in a receiver capable of detecting a training signal and calculating a reliable power measurement in the presence of narrowband interference. A received signal is filtered by a multi-band filter comprising a plurality of sub-band filters. For instance, sub-band filters may be bandpass filters with non-overlapping pass-bands. A training signal is detected by comparing powers of each of the outputs of the sub-band filters to a plurality of thresholds. For example, each sub-band may be assigned a different threshold value. Responsive to detecting a training signal, a power measurement is determined from at least one sub-band filter output. A gain is set based on the determined power measurement, and applied in the receiver.

Abstract: An illustrative multi-lane communication method includes: (a) receiving receive signals on different receive channels; (b) converting each of the receive signals into a lane of a multi-lane receive data stream, wherein said converting includes demodulation and error measurement; (c) determining remote pre-equalizer adaptation information based in part on the error measurement; (d) detecting alignment markers in the multi-lane receive data stream; (e) extracting local pre-equalizer adaptation information in, or proximate to, the alignment markers in the multi-lane receive data stream; (f) using the local pre-equalizer adaptation information to adjust coefficients of a local pre-equalization filter; (g) periodically inserting an alignment marker in a multi-lane transmit data stream, wherein the remote pre-equalizer adaption information is included in, or inserted proximate to, the alignment markers; and (h) transforming each lane of the multi-lane transmit data stream into a transmit signal, wherein said transf

Abstract: Illustrative communications link performance analyzer methods and modules that accommodate FEC. In at least some embodiments, a method for characterizing communications link performance includes: (A) transmitting a predetermined bit stream across a physical communications link to produce a receive signal; (B) deriving a received bit stream from the receive signal with a receiver, the receiver including an embedded debug module having: (1) a bit counter dividing the received bit stream into symbols and frames; (2) an error counter determining a symbol error count for each frame; and (3) an aggregator obtaining at least one performance-related statistic from the symbol error counts; (C) generating a performance measure based on the at least one performance-related statistic; and (D) displaying a visual representation of the performance measure.

Abstract: A transceiver to communicate in a vehicle via a single twisted-pair Ethernet cable includes a transmitter and a receiver, an analog front end, an equalizer, and a controller. The transmitter transmits signals via the single twisted-pair Ethernet cable. The receiver receives signals via the single twisted-pair Ethernet cable. The analog front end receives a first signal received by the transceiver via the single twisted-pair Ethernet cable and outputs a second signal. The equalizer includes a notch filter to cancel electromagnetic interference from the second signal. The controller makes a frequency response of the equalizer independent of the electromagnetic interference by controlling tap values of the notch filter. The controller controls gain of one or more of the analog front end and the equalizer based on the frequency response of the equalizer.

Abstract: Various aspects of this disclosure describe detecting a signal and measuring power with a multi-band filter. Examples include a signal detection and power measurement module in a receiver capable of detecting a training signal and calculating a reliable power measurement in the presence of narrowband interference. A received signal is filtered by a multi-band filter comprising a plurality of sub-band filters. For instance, sub-band filters may be bandpass filters with non-overlapping pass-bands. A training signal is detected by comparing powers of each of the outputs of the sub-band filters to a plurality of thresholds. For example, each sub-band may be assigned a different threshold value. Responsive to detecting a training signal, a power measurement is determined from at least one sub-band filter output. A gain is set based on the determined power measurement, and applied in the receiver.

Abstract: A transceiver to communicate in a vehicle via a single twisted-pair Ethernet cable includes a transmitter to transmit signals via the single twisted-pair Ethernet cable and a receiver to receive signals via the single twisted-pair Ethernet cable. The transceiver includes an equalizer, a signal-to-noise ratio estimator, and a controller. The equalizer includes a notch filter and a slicer. The equalizer receives an input signal received by the transceiver via the single twisted-pair Ethernet cable. The notch filter cancels electromagnetic interference from the input signal and to output a filtered signal. The slicer slices the filtered signal. The signal-to-noise ratio estimator estimates a signal-to-noise ratio based on an output of the slicer. The controller controls a rate of adapting the equalizer by controlling a rate of change of tap values of the notch filter based on the signal-to-noise ratio.

Abstract: A transceiver includes an equalizer, an adaptation module, an error detector, and a controller. The equalizer receives an input signal via the single twisted-pair Ethernet cable, including outputs of an analog front end of the receiver and an echo canceller, to cancel electromagnetic interference from the input signal. The adaptation module adapts parameters of one or more of i) the equalizer, ii) the analog front end, and iii) the echo canceller based on an error in an output of the equalizer due to the electromagnetic interference. The error detector detects when the error is greater than or equal to a predetermined threshold and in response sets an error indicator to indicate no error for a predetermined period of time. The controller controls adaptation of the parameters of the one or more of i) the equalizer, ii) the analog front end, and iii) the echo canceller based on the error indicator.

Abstract: Systems, methods, and other embodiments associated with testing a cable are described. According to one embodiment, an integrated circuit device includes a transmitter, a receiver, cable tester logic and a cable test control logic. The transmitter is configured to transmit signals to a cable. The receiver is configured to receive signals from the cable. The cable tester logic includes an echo tester configured to identify peaks corresponding to echo canceller coefficients that model an impulse response of reflected signals received by the receiver and a power-based cable tester configured to determine a power-based cable length based on an attenuation of a signal received from the link partner. The cable test control logic is configured to selectively activate one or both of the echo tester and the power-based tester and to determine a cable length based, at least in part, on the power-based cable length and the identified peaks.

Abstract: Illustrative communications link performance analyzer methods and modules that accommodate FEC. In at least some embodiments, a method for characterizing communications link performance includes: (A) transmitting a predetermined bit stream across a physical communications link to produce a receive signal; (B) deriving a received bit stream from the receive signal with a receiver, the receiver including an embedded debug module having: (1) a bit counter dividing the received bit stream into symbols and frames; (2) an error counter determining a symbol error count for each frame; and (3) an aggregator obtaining at least one performance-related statistic from the symbol error counts; (C) generating a performance measure based on the at least one performance-related statistic; and (D) displaying a visual representation of the performance measure.

Abstract: Apparatus, methods, and other embodiments associated with reliably determining signal loss over a data communication channel have been described. According to one embodiment, a method includes receiving input signals at an input of a serializer/deserializer device and equalizing the input signals to form equalized signals which compensate for frequency response distortion. The method also includes analyzing the equalized signals to determine whether peak amplitudes of the equalized signals are within a range of amplitudes defined by two threshold values. Furthermore, the method includes analyzing the equalized signals to determine whether logic levels of the equalized signals correspond to a sequence of a same logic level. The method further includes generating a signal absent indicator when the peak amplitudes of the equalized signals are within the range, or when the logic levels of the equalized signals correspond to the sequence of the same logic level.

Abstract: Embodiments include a method comprising: receiving a signal comprising a plurality of symbols; estimating that a first symbol of the plurality of symbols has a first value; based on the first value of the first symbol, cancelling, at least in part, inter symbol interference that the first symbol has on a second symbol of the plurality of symbols; determining a first error associated with the first value of the first symbol; and in response to the first error being higher than a threshold value, generating, for the first symbol, a second value that is different from the first value of the first symbol, and based on the second value of the first symbol, cancelling, at least in part, inter symbol interference that the first symbol has on the second symbol.

Abstract: Systems, methods, and other embodiments associated with echo cancellation are described. According to one embodiment, an apparatus includes a cable tester that determines whether a fault in a cable exists by using echo cancellation values.

Abstract: Systems, methods, and other embodiments associated with echo cancellation are described. According to one embodiment, an apparatus includes a cable tester that determines whether a fault in a cable exists by using echo cancellation values.