from __future__ import annotations
from scipy import signal
from .base.butterworth import Butterworth
[docs]
class Bandpass(Butterworth):
"""Bandpass filter implementation using Butterworth design.
Provides a convenient interface for creating bandpass filters that allow
frequencies within a specific range to pass while attenuating frequencies
outside this range. Uses Butterworth design for maximally flat response.
"""
[docs]
class Configuration(Butterworth.Configuration):
"""Configuration class for Bandpass filter parameters."""
[docs]
class Keys(Butterworth.Configuration.Keys):
"""Configuration keys for bandpass-specific parameters."""
#: Upper cutoff frequency configuration key
F_HI = "f_hi"
#: Lower cutoff frequency configuration key
F_LO = "f_lo"
[docs]
def __init__(self, f_lo: float, f_hi: float, order: int = None, **kwargs):
"""Initialize the bandpass filter with cutoff frequencies.
Args:
f_lo: Lower cutoff frequency in Hz.
f_hi: Upper cutoff frequency in Hz.
order: Filter order. Defaults to DEFAULT_ORDER from parent class.
**kwargs: Additional arguments passed to parent Butterworth class.
Raises:
ValueError: If f_lo >= f_hi or if frequencies are invalid.
"""
# Validate cutoff frequency relationship
if f_lo >= f_hi:
raise ValueError(
"Lower cutoff frequency must be less than upper "
"cutoff frequency."
)
if f_lo <= 0 or f_hi <= 0:
raise ValueError("Cutoff frequencies must be positive.")
# Configure frequency list for bandpass operation
fn = [f_lo, f_hi]
btype = "bandpass"
# Use default order if not specified
if order is None:
order = self.DEFAULT_ORDER
fn = kwargs.pop(Butterworth.Configuration.Keys.FN, fn)
btype = kwargs.pop(Butterworth.Configuration.Keys.BTYPE, btype)
# Initialize parent Butterworth filter with bandpass configuration
super().__init__(
fn=fn, f_lo=f_lo, f_hi=f_hi, btype=btype, order=order, **kwargs
)