A method of providing an improved transfer function for a Discrete Multitone
(DMT)
type modulation transmitter with digital filtering after modulation followed by
digital to analog converter and analog filtering is provided by sending a test
signal to said transmitter and measuring the results of the test signal to determine
the transfer function. The inverse of the transfer function that needs to be compensated
is determined and the inverse of transfer function to be compensated is truncated
to the region of interest (H2). The desired band split component of
pre-compensation filter is designed (H3). The desired target frequency
response of the pre-compensation filter is determined by H4=H2*H3
where H4 is the multiplication of H2 and H3 Given
the target frequency response in H4 Hermetian symmetry is imposed on
the frequency response. The inverse Fourier transform (IFFT) is taken to generate
a time domain filter, h5. The characteristic of this filter is added
at the digital filtering after modulation.