the phase term corresponding that symbol is made available at the receiving accumulator output terminal 46 a depending on the choice of receiving filter function and transmitting filter function the signal at the receiving accumulator output terminal 46 a may need to be scaled this is readily accomplished by feeding that signal into a multiplier 47 a and scaling it by a suitable constant available in a scaling register 49 a the value stored in the scaling register 49 a can be pre selected or can be obtained from a look up table with the exception of differences in the filter functions generated by the receiving filter generator 36 a and in the start and stop times for accumulation as provided by the receiving accumulator controller 48 a the remaining symbol decoders 34 b g operate in the same manner as the first symbol decoder 34 a as shown in fig1 the second symbol decoder 34 b like the first symbol decoder 34 a includes a receiving mixer 35 b and a receiving filter generator 36 b the receiving mixer 35 b has a phaseform terminal 33 b connected to the phase demodulator 32 a receiving filter input terminal 38 b connected to the receiving.