Filter circuitry is constituted by transversal filters which are connected in parallel to each other. The transversal filters change amplitude and a phase of an input digital signal Xin[n·Ts] and output different digital signals X1[n·Ts], X2[n·Ts], and X3[n·Ts] as respective resulting digital signals whose amplitude and phase have been changed. A phase frequency computer computes a phase θX[n·Ts] and a frequency fX[n·Ts] of the input digital signal Xin[n·Ts] by performing phase computation and frequency computation using the digital signals X1[n·Ts], X2[n·Ts], and X3[n·Ts] output by the transversal filters.