Abstract: In a delayed decision feedback sequence estimating apparatus, a transmission channel characteristic is detected for a training signal. A timing detecting unit detects when there is obtained a maximum of ratios of a summation value of absolute values of amplitude components of the transmission channel characteristic for a maximum likelihood sequence estimation region to an addition of a value obtained by multiplying, by a predetermined value, a summation value of absolute values of amplitude components of the transmission channel characteristic for a decision feedback equalization region and a summation value of absolute values of amplitude components of the transmission channel characteristic for a region other than the maximum likelihood sequence estimation region and the decision feedback equalization region, as an out-of-estimation region, to generate a timing signal.

Abstract: A frame step-out detection method and apparatus capable of detecting any frame step-out without having to insert a frame sync pulse or any other additional data, especially when using data mapping, which is transparent to a 90.degree..times.n phase revolution of the input data. During operation input data is encoded and supplied alternately to a first or second mapping table. Each mapping table is transparent to a 90.degree..times.n (n is an integer) phase revolution of the data mapped through that table, but not transparent to a 90.degree..times.n phase revolution of data from the other table. The mapped data is modulated and transmitted to a demodulator. The demodulator generates a signal to select a first or second determination table, which corresponds with the selected first or second mapping table. The demodulated data is determined from the determination table. If an error occurs during data transmission, the wrong determination table will be selected (i.e.