Abstract: The invention relates to a method for equalizing a signal with a frame structure, received via a time-variable transmission channel. According to said method, a frame-type equalization is used. The channel unit pulse response is analyzed and one equalization alternative is selected from several provided alternatives. According to the principle of equalization with decision feedback, it is preferable if only two alternatives are provided; a conventional forward equalization and an inverse-time reversed equalization. A decision in favor of one or the other of these alternatives can be made simply based on the sign characterizing the so-called skewness.

Abstract: The invention discloses a method of measuring the rough frequency deviation in digital communication transmissions with echo propagation, particularly in the short-wave domain. A repeatedly transmitted PN sequence serves as the preamble of a data block. This PN sequence is compressed at the receiving end in matched filters provided in each one of a plurality of simultaneous, frequency offset Doppler channels. The Doppler channel having the greatest amplitude in the quadrature signal is selected for a determination of the rough frequency deviation. To detect a pattern in the preamble, the quadrature signals are examined for similarities by an amplitude comparison or in a cross-correlation process.