the present invention comprises a method of obtaining coefficients for a transmit filter such that the power spectral density of the output for the different frequencies comes close to but does not exceed a maximum power spectral density of a communication standard . by first doing a convex optimization procedure to obtain the autocorrelation coefficients for the filter and then using the autocorrelation coefficients to determine the filter coefficients , a low - order filter that closely approximates the desired output power spectral densities can be produced .