Abstract: A method based on scaling is proposed to estimate the time difference of arrival (TDOA) and scale difference of arrival (SDOA) between two received wideband chirp signals. Using the relation that the square of SDOA equals to the ratio of chirp-rates of two received chirp signals, each chirp-rate of two chirp signals is first estimated using the fractional Fourier transform, and then the SDOA can be evaluated. By scaling one received chirp signal with the estimated SDOA and evaluating the correlation of the scaled chirp signal and the other received chirp signal, the TDOA is finally estimated. Since the 2-D searching of the peak position of the wideband cross ambiguity function is avoided and it can be evaluated using only few fast Fourier transforms, the computational cost is significantly reduced. Simulation results show that the root mean square errors of the estimated TDOA and SDOA using proposed method closely meet to the Cramer-Rao lower bound under high signal-to-noise ratios.