FIELD: digital communication systems. SUBSTANCE: proposed method and device are designed for use in digital communication systems where data are transmitted at variable speed without displaying data transmission speed and received in communication-system receiver where data transmission speed is determined during data processing. Data are received in the form of symbols ordered in data groups. If data are transmitted at full speed, data group is composed of symbols. If data are transmitted at lower speed, symbols are repeated inside data group until the latter is filled up or symbols are spaced apart inside data group. At coding speed equal to, say, one fourth of full speed each symbol of data group is repeated four times or data are transmitted within one fourth of full time. Arriving data groups are decoded by means of decoder such as Viterbi decoder and re-coded by means of coder such as Viterbi coder at each possible data transmission speed. Comparator compares re-coded symbols with those initially received and counter functions to count number of erroneous symbols. Each decoding process organizes display of decoding process characteristics which may include results of check made by means of cyclic redundancy code. Counted errors and characteristics displayed form error metrics conveyed to processor such as microprocessor. Processor analyzes error metrics for each data transmission speed and determines most probable speed at which arriving symbols were coded. EFFECT: provision for determining data transmission speed at which data were coded by means of system receiver. 23 cl, 4 dwg, 1 tbl
