Method and device for training an adaptive equalizer by means of an unknown data signal in a transmission system using double sideband-quadrature carrier modulation

In a data receiver for a synchronous data transmission system wherein the data symbols are transmitted at the signaling rate 1/T. using a double sideband-quadrature carrier modulation technique, said receiver including an adaptive complex equalizer having several tap gains, a method of training said equalizer, characterized in that it includes the steps of:

• applying the signal received from the transmission channel to said equalizer, with said equalizer providing an equalized signal z.sub.n at the signaling instant nT, where the value of n ranges from zero to infinity, in accordance with the following expression:
• z.sub.n =y.sub.n 'C
• where yn is the vector of the signal stored in said equalizer at the signaling instant nT,
• ' denotes transposition of vector yn,
• C is the vector of the tap gain values;
• and adjusting said tap gains so as to minimize the quantity
• D.sup.(1) =E(.vertline.z.sub.n .vertline.-R).sup.2
• where E denotes the mathematical expectation which can be read as "the average value of,"
• R is a positive real constant, and
• .vertline..vertline. denotes the modulus.

In a data receiver for a synchronous data transmission system wherein the data symbols are transmitted at the signaling rate 1/T, using a double sideband-quadrature carrier modulation technique, said receiver including an adaptive complex equalizer having several tap gains, a method of training said equalizer, characterized in that it includes the steps of:

• applying the signal received from the transmission channel to said equalizer, with said equalizer providing an equalized signal z.sub.n at the signaling instant nT, where the value of n ranges from zero to infinity, in accordance with the following expression:
• z.sub.n =y.sub.n 'C
• where y.sub.n is the vector of the signal stored in said equalizer at the signaling instant nT,
• ' denotes transposition of vector y.sub.n,
• C is the vector of the tap gain values;
• determining the distance between a first point representative of said equalized signal in a rectangular coordinates system and a second point having the same phase as said first point and located on a circle of radius R, said distance being designated e.sub.n where said first point corresponds to the equalized signal at the signaling instant nT, and
• adjusting the tap gains of said equalizer in such a way that the average value of the product
• y.sub.n *e.sub.n
• where * denotes the conjugate complex quantity, will tend to approach zero.

In a data receiver for a synchronous data transmission systen wherein the data symbols are transmitted at the signaling rate 1/T, using a double sideband-quadrature carrier modulation technique, said receiver including an adaptive complex equalizer having several tap gains, a method of training said equalizer, characterized in that it includes:

• means for applying the signal received from the transmission channel to said equalizer, with said equalizer providing an equalized signal z.sub.n at the signaling instant nT, where the value of n ranges from zero to infinity, in accordance with the following expression:
• z.sub.n =y.sub.n 'C
• where y.sub.n is the vector of the signal stored in said equalizer at the signaling instant nT, ' denotes transposition of vector y.sub.n, C is the vector of the tap gain values;
• means for generating an error signal in response to said equalized signal, with the error signal e.sub.n generated at the signaling instant nT being defined as:
• e.sub.n =z.sub.n .vertline.z.sub.n .vertline..sup.p-2 (.vertline.z.sub.n -R)
• means for deriving from said error signal control signals for adjusting the tap gains of the equalizer in such a way that the average value of the product
• y.sub.n *e.sub.n
• where * denotes the conjugate complex quantity, will tend to approach zero.

In a data receiver for a synchronous data transmission system wherein the data symbols are transmitted at the signaling rate 1/T, using a double sideband-quadrature carrier modulation technique, said receiver including an adaptive complex equalizer that has several tap gains and supplies the in-phase and quadrature components of the equalized signal, with said equalized signal z.sub.n at signaling instant nT, where the value of n ranges from zero to infinity, being defined as:

• z.sub.n =y.sub.n 'C
• where y.sub.n is the vector of the signals stored in said equalizer at the signaling instant nT,
• ' denotes transposition of vector y.sub.n,
• C is the vector of the tap gain values;
• a device for training said equalizer, characterized in that it includes:
• means for generating the in-phase and quadrature components of an error signal from the in-phase and quadrature components of the equalized signal, with the error signal e.sub.n at the signaling instant nT being defined as
• e.sub.n =z.sub.n -R exp j.omega..sub.n
• where .omega..sub.n is the phase of the equalized signal z.sub.n, and
• R is a positive constant;
• and
• means for deriving from said in-phase and quadrature components of the error signal control signals for adjusting the tap gains of the equalizer so that the average value of the product
• y.sub.n *e.sub.n
• where * denotes the conjugate complex quantity, will tend to approach zero.