FIELD: radio engineering, communication.
SUBSTANCE: method includes quadrature processing of an input signal in four parallel channels. In one pair of channels, the input signal is frequency-converted in an in-phase and quadrature manner relative to the transmission frequency of unit information bits, and relative to the transmission frequency of zero bits in the other pair of channels. The arctangent of the ratio of the quadrature signal component to the in-phase component is calculated for each pair of channels and the obtained phase characteristics are summed and averaged. The averaging result is the phase shift of the signal frequency in the communication channel. To determine signal amplitude distortions, the square root of the sum of squares of the in-phase and quadrature signal components is calculated for each pair of channels and the results are summed. The apparatus which realises said method consist of four multipliers, four low-pass filters, two arctangent calculating units, two devices for calculating the square root of the sum of squares of two values, two adders and an averaging circuit.
EFFECT: determining phase shift variations of the centre frequency of minimum frequency-shift keyed signals in a communication channel independent of the transmitted binary information, high accuracy of measuring phase distortions.
3 cl, 7 dwg, 1 tbl
