Abstract: An apparatus processes an equalizer output signal. The equalizer output signal is formed by transmitting an alternate mark inversion input signal over a channel and passing the transmitted signal through an adaptive equalizer. The apparatus includes a correlator circuit block that detects an incorrect convergence of the adaptive equalizer and outputs a correlator output signal. A corrector filter receives the equalizer output signal and the correlator output signal, and applies a correction to the equalizer output signal based on the correlator output signal, to form a corrected signal that is substantially a time delayed copy of the input signal.

Abstract: The present invention relates to the implementation of a digital adaptive equalizer for a T1/E1 long haul transceiver which is capable of adapting to a wide range of cable types, cable lengths, and/or other data transmission impairments, particularly when the transmission path type and/or length are unknown. The digital adaptive equalizer contains two filter blocks, i.e., an IIR filter and a FIR filter, together with a filter selector block to select a best IIR filter based on an error estimation of the received data. Only a few sets of coefficients are found to be necessary to allow proper digital equalization of a large number of cable types and/or lengths. A filter selector block selects a desired set of coefficients corresponding to the optimum IIR filter. The coefficients may be programmed into volatile memory (e.g., RAM) or non-volatile memory (e.g., Flash). Alternatively, the coefficients may be hardwired into the IIR filter.

Abstract: Initialization of an adaptive equalizer is controlled by varying a gain applied to an input signal. The input signal may be an alternate mark inversion signal. The gain is applied to the input signal to form an amplified signal. An autocorrelation value of the amplified signal is calculated. The autocorrelation value is compared to a predetermined constant. The gain is adjusted, based on which of the group consisting of the autocorrelation value and the predetermined constant is greater. The gain application, autocorrelation calculation, comparison and gain adjustment are repeated, until the autocorrelation value is sufficiently close to the predetermined constant to satisfy a convergence criterion. The amplified signal is then filtered.

Abstract: Initialization of an adaptive equalizer is controlled by varying a gain applied to an input signal. The input signal may be an alternate mark inversion signal. The gain is applied to the input signal to form an amplified signal. An autocorrelation value of the amplified signal is calculated. The autocorrelation value is compared to a predetermined constant. The gain is adjusted, based on which of the group consisting of the autocorrelation value and the predetermined constant is greater. The gain application, autocorrelation calculation, comparison and gain adjustment are repeated, until the autocorrelation value is sufficiently close to the predetermined constant to satisfy a convergence criterion. The amplified signal is then filtered.

Abstract: An apparatus processes an equalizer output signal. The equalizer output signal is formed by transmitting an alternate mark inversion input signal over a channel and passing the transmitted signal through an adaptive equalizer. The apparatus includes a correlator circuit block that detects an incorrect convergence of the adaptive equalizer and outputs a correlator output signal. A corrector filter receives the equalizer output signal and the correlator output signal, and applies a correction to the equalizer output signal based on the correlator output signal, to form a corrected signal that is substantially a time delayed copy of the input signal.