Patent ID: 6263028
Filing Date: 2001-07-17
Classification: H04L

Abstract:
A modulation accuracy measuring apparatus converting an input modulated signal quadrature modulated by digital data into a digital signal, quadrature converting said digital signal into a quadrature converted output, demodulating said quadrature converted output to obtain demodulated data, generating an ideal modulated signal from said demodulated data, and computing modulation accuracy parameters of said input modulated signal from said ideal modulated signal and said digital signal of said input modulated signal, said apparatus comprising:decimation means for decimating said quadrature converted output to a decimated output having a lowest sampling rate which is four times higher than a symbol rate;clock delay estimate means comprising means for detecting a clock delay .DELTA.t from the decimated output of said decimation means; anddelay correcting means for correcting said decimated output of said decimation means with said detected clock delay .DELTA.t to thereby obtain a signal for providing said demodulated data.