Demodulation of a digital modulated waveform requires the symbol rate of a received signal. This parameter may not be known a priori and may need to be estimated in the receiver. This paper studies the use of wavelet transform to estimate the symbol rate of an M-ary phase shift keying (PSK) signal. The idea is to use wavelet transform to locate the transients produced from phase changes. The separation between transients gives a symbol rate estimate. Previous work uses the transform coefficients in a single scale to estimate symbol rate. This paper improves the performance of the estimator by combining the coefficients at several scales before estimation. The accuracy of the estimator is shown to be within 3-6dB of the CRLB, when the sampling rate is four times the carrier frequency and the carrier-to-noise ratio is greater than 7 dB.