US 5,636,244 AGranted

Method and apparatus for initializing equalizer coefficents using peridioc training sequences

AssigneeMotorola, Inc.

InventorsRichard L. Goodson, Lee T. Gusler, Jr., Mickey C. Rushing

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Abstract

An apparatus and method for a data communications device such as a modem (100) to generate initial coefficient values for an equalizer (440) from a transmitted training signal received via a channel, in which the transmitted training signal has predetermined characteristics. The apparatus and method embodiments of the invention determine a finite impulse response characteristic of the inverse frequency response of the channel based on a received training signal and the transmitted training signal (610). In the various embodiments, an energy index, a magnitude index, and an offset index are generated and combined with an equalizer length index to select a sequence of initial coefficient values for the equalizer (630, 640, 650).

Claims25

Dependent claims

An equalizer coefficient generator, the equalizer coefficient generator coupleable to a modem having an initial training period to train an equalizer from a transmitted training signal received via a channel to form a received training signal, the equalizer having a plurality of equalizer coefficients, the transmitted training signal having a predetermined sequence of symbols having known amplitude, phase and frequency characteristics, the modem having a data access arrangement and an analog-digital converter to receive and sample the received training signal to form a sampled signal, the equalizer coefficient generator comprising:

an inverse channel generator coupleable to the analog-digital converter to receive the sampled signal and to convert the sampled signal to form a finite impulse response characteristic of the inverse frequency response of the channel, the finite impulse response characteristic having a plurality of channel coefficients having a predetermined channel length P;
a maximum energy detector coupled to the inverse channel generator to receive the plurality of channel coefficients, the maximum energy detector responsive to detect a maximum energy of a plurality of subsets of adjacent channel coefficients, each of the plurality of subsets of adjacent channel coefficients having a predetermined length J and having subset coefficients, the maximum energy detector further responsive to form an energy index V corresponding to a subset of adjacent channel coefficients of the plurality of subsets of adjacent channel coefficients having the maximum energy;
a maximum magnitude detector coupled to the inverse channel generator to receive the plurality of channel coefficients, the maximum magnitude detector responsive to detect a maximum magnitude of the plurality of channel coefficients and to form a magnitude index W corresponding to a channel coefficient of the plurality of channel coefficients having the maximum magnitude;
and
a coefficient selector coupled to the inverse channel generator, the maximum energy detector, and the maximum magnitude detector, for determining a subset of adjacent channel coefficients of the plurality of subsets of adjacent channel coefficients, from the energy index V and the magnitude index W, to form a set of initial values for the plurality of equalizer coefficients.

2 more elements

A modem for data transmission and reception, the modem having an initial training period to train an equalizer from a transmitted training signal received via a channel to form a received training signal, the equalizer having a plurality of equalizer coefficients, the transmitted training signal having a predetermined sequence of symbols having known amplitude, phase and frequency characteristics, the modem comprising:

a data access arrangement coupleable to the channel to receive the received training signal;
an analog-digital converter coupled to the data access arrangement to sample the received training signal to form a sampled signal;
and
a processor, the processor coupled to the analog-digital converter to receive the sampled signal, the processor responsive to form a finite impulse response characteristic of the inverse frequency response of the channel, the finite impulse response characteristic having a plurality of channel coefficients having a predetermined channel length P;
the processor further responsive to detect a maximum energy of a plurality of subsets of adjacent channel coefficients, each of the plurality of subsets of adjacent channel coefficients having a predetermined length J and having subset coefficients, the processor further responsive to form an energy index V corresponding to a subset of adjacent channel coefficients of the plurality of subsets of adjacent channel coefficients having the maximum energy;
the processor further responsive to detect a maximum magnitude of the plurality of channel coefficients and to form a magnitude index W corresponding to a channel coefficient of the plurality of channel coefficients having the maximum magnitude;
and the processor further responsive to determine a subset of adjacent channel coefficients of the plurality of subsets of adjacent channel coefficients, from the energy index V and the magnitude index W, to form a set of initial values for the plurality of equalizer coefficients.

4 more elements

A method for generating a set of initial values for a plurality of equalizer coefficients, from a transmitted training signal received via a channel to form a received training signal, the transmitted training signal having a predetermined sequence of symbols having known amplitude, phase and frequency characteristics, the method comprising:

(a) sampling the received training signal to form a sampled signal;
(b) converting the sampled signal to form a finite impulse response characteristic of the inverse frequency response of the channel, the finite impulse response characteristic having a plurality of channel coefficients having a predetermined channel length P;
(c) detecting a maximum energy of a plurality of subsets of adjacent channel coefficients, each of the plurality of subsets of adjacent channel coefficients having a predetermined length J and having subset coefficients, and forming an energy index V corresponding to a subset of adjacent channel coefficients of the plurality of subsets of adjacent channel coefficients having the maximum energy;
(d) detecting a maximum magnitude of the plurality of channel coefficients and forming a magnitude index W corresponding to a channel coefficient of the plurality of channel coefficients having the maximum magnitude;
and
(e) determining a subset of adjacent channel coefficients of the plurality of subsets of adjacent channel coefficients, from the energy index V and the magnitude index W, to form the set of initial values for the plurality of equalizer coefficients.

3 more elements

Dependencies are inferred from the claim text.