Method of and apparatus for automatic equalizing filter

An automatic equalizing filter for a time division multiple access system, comprising:

• a reception signal input for receiving a reception signal;
• synchronizing data detecting means for detecting a synchronizing data portion from a data sequence of said reception signal, said synchronizing data detecting means receiving said reception signal from said reception signal input;
• a transversal filter equalizer having tap coefficients, said equalizer receiving said reception signal from said reception signal input, said equalizer also receiving values of said tap coefficients;
• tap coefficient determining means for determining said tap coefficients of said equalizer, said tap coefficient determining means receiving an error signal;
• wherein said data sequence is arranged in frames and wherein initial values of said tap coefficients of said equalizer are set at every frame;
• impulse response estimating means for estimating an impulse response from a cross-correlation function between said synchronizing data portion and previously-designated synchronizing pattern;
• initial value determining means for generating said initial values of said tap coefficients of said equalizer, wherein said cross-correlation function is received from said impulse response estimating means and processed to provide said initial values to said tap coefficient determining means;
• wherein said cross-correlation function is processed using a Fourier transform to calculate an inverse filter transfer characteristic, said inverse filter transfer characteristic is processed using an inverse Fourier transform to produce output values, and said output values are employed as said initial values of said tap coefficients of said equalizer;
• and
• said initial value determining means includes a memory, wherein said tap coefficients of said equalizer corresponding to the cross-correlation function between said synchronizing data portion and said synchronizing pattern in said impulse response estimating means are calculated in advance, said tap coefficients are stored in said memory and said tap coefficients as said initial values of said equalizer are set by reading said tap coefficients from said memory on the basis of said cross-correlation function calculated by said impulse response estimating means upon reception of said reception signal.

A method for providing an automatic equalizing filter for a time division multiple access system, comprising the steps of:

• detecting a synchronizing data portion from a data sequence of a reception signal, wherein said data sequence is arranged in frames;
• providing a transversal filter equalizer having tap coefficients, said equalizer receiving said reception signal, said equalizer also receiving values Of said tap coefficients;
• estimating an impulse response from a cross-correlation function between said synchronizing data portion and a previously-designated synchronizing pattern;
• setting initial values of said tap coefficients at a predetermined number of said frames by processing said cross correlation function;
• determining said tap coefficients of said equalizer on the basis of said initial values;
• wherein said cross-correlation function is processed using a Fourier transform to calculate an inverse filter transfer characteristic, said inverse filter transfer characteristic is processed using an inverse Fourier transform to produce output values, and said output values are employed as said initial values of the tap coefficients of said equalizer.