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.