goertzel

Functions

int main(int argc, char *argv[])

goertzel [ option ] [ infile ]

-l int
- FFT length \((1 \le L)\)
-m int
- order of sequence \((0 \le M)\)
-s double
- sampling rate [kHz] \((0 < F_s)\)
-f double+
- frequencies [Hz] \((0 \le F_k < 500F_s)\)
-o int
- output format
  - 0 real and imaginary parts
  - 1 real part
  - 2 imaginary part
  - 3 amplitude
  - 4 power
infile str
- double-type data sequence
stdout
- double-type DFT sequence

The below example analyzes a sine wave using Goertzel algorithm.

sin -p 30 -l 256 | goertzel -l 256 -o 3 > sine.amp

Parameters:

argc – [in] Number of arguments.
argv – [in] Argument vector.

Returns:

0 on success, 1 on failure.

See also

fftr

class GoertzelAnalysis

Calculate DFT values at specified frequencies using the Goertzel algorithm.

The input is the \(L\)-length waveform signals:

\[ \begin{array}{cccc} x(0), & x(1), & \ldots, & x(L-1). \end{array} \]

The outputs are the real and imaginary parts of the DFT values:

\[\begin{split} \begin{array}{cccc} \mathrm{Re}(X(0)), & \mathrm{Re}(X(1)), & \ldots, & \mathrm{Re}(X(K-1)), \\ \mathrm{Im}(X(0)), & \mathrm{Im}(X(1)), & \ldots, & \mathrm{Im}(X(K-1)), \end{array} \end{split}\]

where \(K\) is the number of frequencies to be analyzed.

Public Functions

GoertzelAnalysis(double sampling_rate, const std::vector<double> &frequencies, int fft_length)

Parameters:

sampling_rate – [in] Sampling rate in Hz.
frequencies – [in] \(K\) frequencies in Hz to be analyzed.
fft_length – [in] Number of points assumed in DFT. This is used to determine frequency bin resolution.

inline bool IsValid() const

Returns:: True if this object is valid.

bool Run(const std::vector<double> &signals, std::vector<double> *real_part_output, std::vector<double> *imag_part_output) const

Parameters:

signals – [in] \(L\)-length waveform signals.
real_part_output – [out] \(K\) real parts.
imag_part_output – [out] \(K\) imaginary parts.

Returns:

True on success, false on failure.