1. A method of correlating a signal comprising the steps of: (a) selecting a plurality of samples of said signal; (b) modifying a first butterfly transform with a first twiddle factor; (c) transforming said samples with said modified first butterfly transform; (d) modifying a second butterfly transform with a second twiddle factor; (e) transforming an output of said of said first butterfly transform with said modified second butterfly transform; modifying a third butterfly transform with a third twiddle factor; (g) transforming an output of said second butterfly transform with said modified third butterfly transform; (h) selecting a largest output of said third butterfly transform; and (i) repeating steps (a)-(h) for a plurality of values of said first, said second, and said third twiddle factors.