ADAPTIVE DIGITAL FREQUENCY DISCRIMINATOR Russian patent published in 2001 - IPC

FIELD: radio engineering, radar and radio communication system measuring frequency of continuous or amplitude-modulated radio signal received against background of noise. SUBSTANCE: adaptive digital frequency discriminator has input amplitude limiter, reference signal generator, two multipliers, π/2 phase shifter, first sign flip-flop, Schmitt flip-flop, former of synchronization pulses, control unit, unit matching time of readings, shift register, N-digit reversible counter, AND gate, first and second n-input AND gates, controlling flip-flop, OR gate and reversible counter with limited counting with proper couplings. Discriminator is supplemented with unit eliminating rattle having two inputs connected correspondingly to outputs of first and second multipliers, second output of this unit is connected to signal input of unit matching time of readings, first and second outputs of unit eliminating rattle are connected to inputs of unit averaging sign whose output is output of potential of sign. Control unit is inserted with frequency divider with changeable count-down ratio whose input is linked to input of control unit and whose output is connected to input of former of synchronization pulses. Controlling inputs of frequency divider with changeable countdown ratio are connected to outputs of reversible counter with limited counting. Output of Schmitt flip-flop is attached to output of input amplitude limiter and its output is linked to second inputs of first and second multipliers. Discriminator is also inserted with unit changing form of discrimination characteristic whose inputs are connected to outputs of reversible counter with limited counting, controlling inputs are linked to output of first sign flip-flop and to direct outputs of N-digit reversible counter. Outputs of unit changing form of discrimination characteristic are outputs of discriminator. EFFECT: enhanced noise immunity thanks to more complete usage of elements of storage of discriminator under all conditions of signal processing and to possibility of adaptive change of slope and form of discrimination characteristic. 5 dwg