Connecting custom sensor to RC dig I/O

[TubaMorg]

Here's a question for you electrical gurus:

We made a signal sensor that outputs around 2.9 volts until a signal is received at which point the output goes up to around 3.8 volts. We didn't get a chance to hook this up to the RC before ship, but we are wondering what we need to do to make this output work with the digital inputs on the RC. The RC manual says that the input pins expect a 0v or 5v signal, so how do we make our tweener signal work?