A method and apparatus for accurately detecting the presence of a valid signal includes processing that begins by determining the energy level of an input signal in real time to produce a real time energy level. The processing then continues by delaying the input by a period of the valid signal to produce a delayed input. The processing then continues by correlating the input with the delayed input to produce a correlated input. The processing continues by determining the energy of the correlated input to produce a correlated energy level. The processing then continues by comparing the correlated energy level with the real time energy level to produce a probability that the input is a valid signal. The processing then continues by generating a valid signal probability indication based on the probability that the input is a valid signal.