An interface system delivers an output signal having a first signal characteristic in response to first and second input signals having the first signal characteristic and a second, different signal characteristic. The interface system includes a signal input for receiving a first signal having a first signal characteristic and a second signal having a second signal characteristic which is different from the first signal characteristic, a detector circuit for detecting whether the signal at the input is the first signal or the second signal, and a translator circuit for translating either of the first signal or the second signal into the output signal.