Demodulator for frequency-shift keyed signals by using the goertzel algorithm
AssigneeABB Technology AG
InventorStefan POOK
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Abstract
Exemplary embodiments relates to a demodulator for frequency-shift keyed signals by using the Goertzel algorithm according to the general recursive calculating rule, where c re = 2 * cos ( 2 * π * f g f s ) with the sampling frequency fs and the specified frequency fg. To reduce the mathematical complexity in feed-power-limited devices, it is proposed that the sampling frequency fs is an integral multiple of the frequency fg of a specified discrete spectral component.
Claims14
A demodulator for frequency-shift keyed signals, comprising:
- a processor configured to filter input signals and process the filtered signals using a Goertzel algorithm according to a general recursive calculating rule M=s[n]2+s[n−1]2+s[n]*s[n−1]*cre
- where s[n]=x[n]+cre*s[n−1]−s[n−2],
- M is the magnitude of a specified discrete spectral component,
- x[n] are the samples of the input signal,
- s[n] are state signals, and
- cre is the feedback coefficient of the state signal s[n−1],
- where
- c
- re
- =
- 2
- *
- cos
-
- (
- 2
- *
- π
- *
- f
- g
- f
- s
- )
- with a sampling frequency fs and a specified frequency fg, and
- wherein the sampling frequency fs is an integral multiple of the frequency fg of the specified discrete spectral component.
A method for demodulating frequency-shift keyed signals, comprising:
- filtering input signals in a processor;
- processing, in a processor, the filtered signals using a Goertzel algorithm according to a general recursive calculating rule M=s[n]2+s[n−1]2+s[n]*s[n−1]*cre
- where s[n]=x[n]+cre*s[n−1]−s[n−2],
- M is a magnitude of a specified discrete spectral component,
- x[n] are samples of the input signal,
- s[n] are state signals, and
- cre is a feedback coefficient of the state signal s[n−1],
- where
- c
- re
- =
- 2
- *
- cos
-
- (
- 2
- *
- π
- *
- f
- g
- f
- s
- )
- with a sampling frequency fs and a specified frequency fg, and
- wherein the sampling frequency fs is an integral multiple of the frequency fg of the specified discrete spectral component.
A demodulator for frequency-shift keyed signals, comprising:
- a processor configured to filter a line signal, sample the filtered signal and process samples output from the filter with a Goertzel algorithm, comparing a result of the algorithm to a threshold to determine whether the filter output is to be fedback for further processing with the Goertzel algorithm.
Dependencies are inferred from the claim text.