tcad-bodeplot/dea/bode.py

import numpy as np
from fastapi import HTTPException
from scipy import signal

from .config import BODE_MAX_MULTIPLIER, BODE_POINTS
from .schemas import BodeCompareParams, BodeParams
from .validation import require_finite, validate_coefficients


def _bode_series(b_values, a_values, f_eval, fs_val):
    b_vals = validate_coefficients(b_values, "b")
    a_vals = validate_coefficients(a_values, "a")
    _, h = signal.freqz(b_vals, a_vals, worN=f_eval, fs=fs_val)
    return {
        "mag": (20 * np.log10(np.abs(h) + 1e-12)).tolist(),
        "phase": np.angle(h, deg=True).tolist(),
    }


def _frequency_axis(fs):
    fs_val = require_finite(fs, "fs")
    f_min = fs_val / 50000.0
    f_max = fs_val * BODE_MAX_MULTIPLIER
    return fs_val, np.logspace(np.log10(f_min), np.log10(f_max), BODE_POINTS)


def calculate_bode_response(params: BodeParams):
    fs_val, f_eval = _frequency_axis(params.fs)
    series = _bode_series(params.b, params.a, f_eval, fs_val)
    return {
        "freq": f_eval.tolist(),
        "mag": series["mag"],
        "phase": series["phase"],
    }


def calculate_bode_compare_response(params: BodeCompareParams):
    fs_val, f_eval = _frequency_axis(params.ideal.fs)
    fixed_fs_val = require_finite(params.fixed.fs, "fixed.fs")
    if not np.isclose(fixed_fs_val, fs_val):
        raise HTTPException(status_code=400, detail="ideal 與 fixed 的 fs 必須相同")

    ideal = _bode_series(params.ideal.b, params.ideal.a, f_eval, fs_val)
    fixed = _bode_series(params.fixed.b, params.fixed.a, f_eval, fs_val)
    return {
        "freq": f_eval.tolist(),
        "ideal": ideal,
        "fixed": fixed,
    }