Digital signal processing¶

Filtering¶

class sdr.FIR

Implements a finite impulse response (FIR) filter.

class sdr.IIR

Implements an infinite impulse response (IIR) filter.

Multirate filtering¶

class sdr.Interpolator(sdr.FIR)

Implements a polyphase finite impulse response (FIR) interpolating filter.

class sdr.Decimator(sdr.FIR)

Implements a polyphase finite impulse response (FIR) decimating filter.

sdr.multirate_taps(P: int, Q: int = 1, ...) → ndarray

Computes the multirate FIR filter that achieves rational resampling by \(P/Q\).

sdr.polyphase_matrix(P: int, Q: int, taps: ArrayLike) → ndarray

Converts the multirate FIR filter taps \(h_i\) into the polyphase matrix \(H_{i, j}\) that achieves rational resampling by \(P/Q\).

Resampling¶

class sdr.FarrowResampler

Implements a cubic Farrow arbitrary resampler.

Correlation¶

Signal manipulation¶

sdr.mix(x: ArrayLike, freq: float = 0, ...) → ndarray

Mixes the time-domain signal \(x[n]\) with a complex exponential or real sinusoid.

sdr.to_complex_bb(x_r: ArrayLike) → ndarray

Converts the real passband signal \(x_r[n]\) centered at \(f_{s,r}/4\) with sample rate \(f_{s,r}\) to a complex baseband signal \(x_c[n]\) centered at \(0\) with sample rate \(f_{s,c} = f_{s,r}/2\).

sdr.to_real_pb(x_c: ArrayLike) → ndarray

Converts the complex baseband signal \(x_c[n]\) centered at \(0\) with sample rate \(f_{s,c}\) to a real passband signal \(x_r[n]\) centered at \(f_{s,r}/4\) with sample rate \(f_{s,r} = 2f_{s,c}\).

sdr.upsample(x: ArrayLike, rate: int) → ndarray

Upsamples the time-domain signal \(x[n]\) by the factor \(r\).

sdr.downsample(x: ArrayLike, rate: int) → ndarray

Downsamples the time-domain signal \(x[n]\) by the factor \(r\).