A control method for a decision feedback equalizer (DFE) includes: generating a channel impulse response (CIR) estimation vector according to an input signal at a CIR estimation frequency; generating an FFE coefficient according to the CIR estimation vector at a first frequency; generating an FBE coefficient according to the CIR estimation vector, and the FFE coefficient at a second frequency; generating a feed-forward equalization filtered result according to the input signal and the FFE coefficient; generating a feed-backward equalization filtered result according to a decision signal and the FBE coefficient; and generating an updated decision signal according to the feed-forward equalization filtered result and the feed-backward equalization filtered result. At least one of the first frequency and the second frequency is smaller than the CIR estimation frequency.

The present invention relates to inspection apparatus for use in wellbores in the oil and gas industries. In particular the invention relates in general to the field of transmission of data between downhole module in a wellbore and a controlling module at the surface. The invention provides a method and apparatus for determining analog filter parameters for an analog front end comprising a plurality of filter stages receiving signals from a telemetry module, by repeating the steps of; receiving a signal of a known frequency and processing said signal by determining the magnitude of the frequency of the received signal until a plurality of signals have been received and processed; calculating an optimum set of filter parameters in dependence upon the measured frequency magnitudes and a predefined set of filter stage frequency responses.

A method of blind tap coefficient adaptation includes receiving a digital data signal including random digital data, equalizing a first portion of the digital data signal using a first set of predetermined tap coefficients and a second portion of the digital data signal using a second set of predetermined tap coefficients. The method includes generating a first eye diagram and a second eye diagram from a first portion and a second portion of an equalized signal, respectively. The first eye diagram is compared with the second eye diagram to determine which of the sets of predetermined tap coefficients results in a data signal having a higher signal quality. The method includes inputting to an equalizer as an initial set of tap coefficients the first set of predetermined tap coefficients or the second set of predetermined tap coefficients according to the determination.

Transmission line driver systems are described which are comprised of multiple paralleled driver elements. The paralleled structure allows efficient generation of multiple output signal levels with adjustable output amplitude, optionally including Finite Impulse Response signal shaping and skew pre-compensation.

This disclosure relates to a receiver device for pulse amplitude modulation (PAM) signals. The receiver device calculates a transmitter dispersion eye closure quaternary (TDECQ). The receiver device first obtains a signal, wherein the signal is based on a PAM signal sent by a transmitter device over a channel to the receiver device, and filters the obtained signal. Further, the transmitter device equalizes the filtered signal using a FFE with multiple taps, and filters the equalized signal output by the FFE using a 2-tap post filter, wherein high frequency noise caused by the FFE is compressed. The receiver device applies a Max-Log-Map (MLM) algorithm on the filtered signal output by the 2-tap post filter, reconstructs a signal constellation of the PAM signal based on the result of the MLM algorithm, and calculates a TDECQ based on the reconstructed signal constellation.

Apparatuses, methods, and systems are disclosed for determining a composite zero-forcing equalizer. One method includes measuring a first frequency response at a first antenna connector. The method includes determining a first zero-forcing equalizer for the first antenna connector as an inverse of the first frequency response. The method includes measuring a second frequency response at a second antenna connector. The method includes determining a second zero-forcing equalizer for the second antenna connector as an inverse of the second frequency response. The method includes determining a composite zero-forcing equalizer as a normalized power weighted linear combination of absolute value magnitudes of the first zero-forcing equalizer and the second zero-forcing equalizer.