  The calculation of the transmission power spectrum of QSO's Lyman alpha
absorption requires two parameters for the normalization: the continuum Fc and
mean transmission, i.e. average of e^{-tau}. Traditionally, the continuum is
obtained by a polynomial fitting truncating it at a lower order, and the mean
transmission is calculated over the entire wavelength range considered. The
flux F is then normalized by the average of Fc e^{-tau}. However, the
fluctuations in the transmitted flux are significantly correlated with the
local background flux on scales for which the field is intermittent. In this
paper, we develop a self-normalization algorithm of the transmission power
spectrum based on a multiresolution analysis. This self-normalized power
spectrum estimator needs neither a continuum fitting, nor pre-determining the
mean transmission. With simulated samples, we show that the self-normalization
algorithm can perfectly recover the transmission power spectrum from the flux
regardless of how the continuum varies with wavelength. We also show that the
self-normalized power spectrum is also properly normalized by the mean
transmission. Moreover, this power spectrum estimator is sensitive to the
non-linear behavior of the field. That is, the self-normalized power spectrum
estimator can distinguish between fields with or without the
fluctuation-background correlation. This cannot be accomplished by the power
spectrum with the normalization by an overall mean transmission. Therefore, the
self-normalized power spectrum would be useful for the discrimination among
models without the uncertainties caused by free (or fitting) parameters.
