zlw 0.0.1

Zero Latency Whitening Utilities

zlw — Zero‑Latency Whitening utilities

zlw is a small, focused package that provides zero‑latency whitening utilities for gravitational‑wave data analysis. It includes:

• Whitening filter utilities
  • Minimum‑phase, zero‑latency whitening filters and helpers
  • Supporting Fourier/window helpers for stable, real‑time responses
• MP–MP scheme PSD drift correction terms
  • Utilities to compute first‑ and second‑order timing and phase correction terms
  • Tools to account for slow PSD mismatches between template and data

Where things live:

• zlw.kernels: minimum‑phase whitening filter construction and frequency‑response utilities
• zlw.fourier, zlw.window: helpers used by the whitening filters
• zlw.corrections: MP–MP scheme PSD drift correction terms (class MPMPCorrection)
• zlw/tests: basic tests (e.g., tests/test_kernels.py)
• zlw/src/zlw/bin: small simulation/QA scripts

Quick examples

• Whitening filter

  from zlw.kernels import MPWhiteningFilter

  psd: one‑sided PSD array (Hz^-1), fs: sampling rate (Hz), n_fft: FFT length

  wf = MPWhiteningFilter(psd, fs, n_fft) Wf = wf.frequency_response() # one‑sided frequency response (complex for min‑phase)

• MP–MP correction terms

  import numpy as np from zlw.corrections import MPMPCorrection

  freqs: one‑sided frequency grid; psd1: data PSD; psd2: template PSD; htilde: template FFT

  corr = MPMPCorrection(freqs=freqs, psd1=psd1, psd2=psd2, htilde=htilde, fs=fs)

  Simple first‑order corrections

  dt1, dphi1 = corr.simplified_correction()

  Or the full second‑order set (includes cross terms)

  (dt1, dphi1), (dt2, dphi2) = corr.full_correction()

Notes

• “Zero‑latency” refers to the use of minimum‑phase whitening filters so that the whitening operation does not introduce group delay in the time domain.
• The MP–MP correction utilities follow the perturbative scheme that expands about the ratio of PSDs, providing drift terms for coalescence time and phase when the whitening filters differ slightly.