Modulation codes used in some digital recording systems must satisfy the charge constraint in addition to the (d,k) constraint. A construction technique is presented in this work for charge constrained (1,k greater than or equal to 4) codes. The construction technique is based on a merging bit rule and dklr-sequences with l=r=k-3. Decoding of the constructed codes is state independent, and no error propagation occurs during decoding. The generating function of dklr-sequences is derived with information regarding sequence length, charge and weight; and coding rate of charge constrained (1,k greater than or equal to 4) codes is tabulated. A comparison is also made of the efficiency of a (1,5,10) code with coding rate 8/16 constructed by this technique with that of the M(2) (1,5,3) code when used with error correcting codes.
