Demodulator for frequency shift keyed signals using the goertzel - algorithm

摘要

Demodulator for frequency shift keyed signals using the goertzel - algorithm according to the general recursive calculation rule$\text{M}=\text{s}{\left[\text{n}\right]}^2+\text{s}{\left[\text{n}-1\right]}^2+\text{s}\left[\text{n}\right]*\text{s}\left[\text{n}-1\right]*{\text{c.}}_{\text{re}}$with$\text{s}\left[\text{n}\right]=\text{x}\left[\text{n}\right]+{\text{c.}}_{\text{re}}*\text{s}\left[\text{n}-1\right]-\text{s}\left[\text{n}-2\right]$whereinM is the magnitude of the desired discrete spectral component,x [n] the sampling values of the input signal,s [n] status signals andc._re the feedback coefficient of the condition signal s [n - 1],${\mathrm{c.}}_{re}=2\ast \text{cos}\left(2\ast \pi \ast \frac{f_g}{f_s}\right)$with the sampling frequency f_s and of the desired frequency f_g , which is characterized in that the sampling frequency f_s for the demodulation of fsk - signals which, in automation technology for communication between the central and peripheral devices are used, the peripheral devices for reasons of explosion protection are fed from a power-limited conductor loop, exactly four times the frequency f_g the sought discrete spectral component is.