that are applied to the symbols for transmission due to varying back off requirements in prior art variable modulation systems when the modulation scheme changes the memory of the fir filter is not normally reset while the weights w 0 to wk are instantly changed to weights optimized for the modulation scheme or symbols of the scheme to prevent spectrum spillage this solution is not ideal however because the weights are then not optimized for the symbols in the memory taps 62 of the filter that correspond to the previous modulation scheme or rate one solution is to employ one set of weights for all modulation schemes this solution is also not ideal however since the fir filter is then not optimized for the alphabet of symbols for each modulation scheme to prevent spectrum spillage and optimize the fir filter 60 the present invention changes the filter taps sequentially with each new symbol from the new modulation scheme as shown in fig8 a to 8f in particular the weight that corresponds to the first new symbol of a new modulation scheme is modified as the first new symbol propagates through the filter 60 in fig8 a the filter weights w 0 to wk are optimized for the modulation scheme of the symbols currently being processed by the fir filter 60 in fig8 b the first symbol of a new modulation scheme is received in t 0 of the fir filter 60 at this point as shown in fig8 b the present invention replaces the filter weight w 0 associated with t 0 with a new filter weight w 0 u2032 where w 0 u2032 is optimized for the modulation scheme of the first new symbol stored in t 0 then.