The origins of DCC can be traced back to 1940s when Lionel Trains introduced a commercial two-channel system using frequency control. An oscillator generated different frequencies, depending on which button an operator might press. Then a tuned circuit and relay in each engine controlled the direction of the train.
GE, in the early sixties, introduced a five-channel commercial carrier control system called ASTRAC (Automatic Simultaneous Train Control), which could control more than one train per block.
Systems such as Dynatrol’s CTC-16 from late 1970s were popular but suffered from lack of compatibility among competing systems. This is partly why National Model Railroad Association (NMRA) introduced standards for Digital Command Control based on proposal by Lenz. All manufacturers have to abide by this standard in order to receive NMRA conformance approval.
As a result of NMRA conformance standards, a digital signal from a command station can be received by any number of commercially available decoders.