Apparatus for adjusting signal points, equalizer coefficients and the like

Apparatus for receiving a communication signal communicated over a communication medium, the communication signal modulated to include digital data in the form of a train of symbols based on a predetermined transmit constellation of signal points, each signal point of the transmit constellation representing a digital code, each symbol of the train having a symbol period and positioned by modulation substantially at the signal point of the transmit constellation corresponding to the digital data code intended to be represented thereby in the train, the modulated symbols of the communication signal being distortable in the communication thereof, the apparatus arranged for processing the received modulated symbols in accordance with a receive constellation of signal points to retrieve the digital data thereof, the apparatus comprising:

• means for demodulating at each symbol period a modulated symbol from the received communication signal to generate a demodulator output, D(k);
• means for equalizing the demodulator output by processing the demodulator output and at least one other demodulator output D(k.+-.m) with corresponding equalizing coefficients to yield an equalized symbol R(k);
• means for identifying a signal point S.sub.n (k) of the receive constellation corresponding to the equalized symbol R(k) based on a predetermined criteria, the signal point S.sub.n (k) being used to retrieve the digital data code of the equalized symbol R(k);
• and
• means for adjusting the equalizing coefficients based on the difference between the equalized symbol R(k) and the identified signal point S.sub.n (k), the at least one other demodulator output D(k.+-.m), and an adaptive gain factor, the adjusted equalizing coefficients being used by the equalizing means to process at least one subsequent demodulator output D(k+1) of the train.

Apparatus for receiving a communication signal communicated over a communication medium, the communication signal modulated to include digital data in the form of a train of symbols based on a predetermined transmit constellation of signal points, each signal point of the transmit constellation representing a digital code, each symbol of the train having a symbol period and positioned by modulation substantially at the signal point of the transmit constellation corresponding to the digital data code intended to be represented thereby in the train, the modulated symbols of the communication signal being distortable in the communication thereof, the apparatus arranged for processing the received modulated symbols in accordance with a receive constellation of signal points to retrieve the digital data thereof, the apparatus comprising:

• means for demodulating at each symbol period a modulated symbol from the received communication signal to generate a demodulator output, D(k);
• means for equalizing the demodulator output by processing the demodulator output and at least one other demodulator output D(k.+-.m) with corresponding equalizing coefficients to yield an equalized symbol R(k);
• means for identifying a signal point S.sub.n (k) of the receive constellation corresponding to the equalized symbol R(k) based on a predetermined criteria, the signal point S.sub.n (k) being used to retrieve the digital data code of the equalized symbol R(k);
• first adjusting means for adjusting the equalizing coefficients based on a difference between the equalized symbol R(k) and the identified signal point S.sub.n (k), the at least one other demodulator output D(k.+-.m), and an adaptive gain factor, the adjusted equalizing coefficients being used by the equalizing means to process at least one subsequent demodulator output D(k+1) of the train;
• and
• second adjusting means for adjusting the identified signal point from its current position S.sub.n (k) to a new position S.sub.n (k+1) in the receive constellation based on the position of the equalized symbol R(k) in relation to the current position S.sub.n (k) for use by the identifying means in identifying the signal point of the receive constellation corresponding to at least one subsequently equalized symbol R(k+1) of the train.