Patent ID: 6072997
Filing Date: 2000-06-06
Classification: H03D,H03K,H04B

Abstract:
In a frequency discriminator for a direct conversion type FM receiver, comprising:direct conversion means for converting an FM signal into an inphase signal component x and a quadrature signal component y in a base band;analogue/digital converting means for converting both said signal components into digital signals;differentiating means for obtaining differentials x', y' of said digital signals; andoperating means for obtaining squares x'.sup.2, y'.sup.2 of said differentials x', y' to obtain a demodulated output of said FM signal by obtaining a sum of said squares and by obtaining a square root of said sum,the improvement wherein said operating means consists of an ROM and an adder and squares x'.sup.2, y'.sup.2 and square roots ##EQU2## are stored in said ROM, and said ROM is connected to said differentiating means and said adder so that said squares x'.sup.2, y'.sup.2 from the ROM is added by said adder and said square roots ##EQU3## corresponding to said sum x'.sup.2 +y'.sup.2 from the adder is outputted from the ROM.