Fast method to detect specific frequencies in monitored signal

The Discrete Fourier Transform (DFT) is a mathematical procedure that stands at the center of the processing that takes place inside a Digital Signal Processor. It has been known and argued through the literatures that the Fast Fourier Transform (FFT) is useless in detecting a specific frequency in a monitored signal because most of the computed results are ignored. In this paper we will present an efficient FFT based method to detect specific frequencies in a monitored signal which is compared to the most frequently used method ¿the Goertzel´s Algorithm¿. Parallel implementation structure show a fast computation method compared to the Goertzel´s algorithm. Computational speedup gains of r using radix-r butterfly are shown.