by Claude Code & https://github.com/LewisLiuLiuLiu/SerDesSystemCProject/tree/main/eye_analyzer

plot_eyes_wi_EyeAnalyzer.py

"""Plot statistical and empirical eye diagrams from the smoke test fixtures."""

import os
import sys

import matplotlib
# matplotlib.use("Agg")
import matplotlib.pyplot as plt
import numpy as np

sys.path.insert(0, "/path/to/SerDesSystemCProject")
from eye_analyzer import EyeAnalyzer

UI = 100e-12
DT = 1e-12
RNG = np.random.default_rng(42)


def make_pulse_response(ui=UI, dt=DT, n_ui=20, tau_frac=0.3):
    sps = int(round(ui / dt))
    t = np.arange(n_ui * sps) * dt
    tau = tau_frac * ui
    in_sig = (t < ui).astype(float)
    # Backward-Euler discretization: y[n] = (1-α)·y[n-1] + α·x[n]
    alpha = dt / (tau + dt)
    out = np.zeros_like(in_sig)
    out[0] = alpha * in_sig[0]
    for k in range(1, len(in_sig)):
        out[k] = out[k - 1] + alpha * (in_sig[k] - out[k - 1])
    return out


def make_nrz_waveform(ui=UI, dt=DT, n_bits=4000, noise=0.02):
    sps = int(round(ui / dt))
    bits = RNG.choice([-0.4, 0.4], size=n_bits)
    raw = np.repeat(bits, sps).astype(float)
    tau = 0.3 * ui
    # Backward-Euler discretization: y[n] = (1-α)·y[n-1] + α·x[n]
    alpha = dt / (tau + dt)
    sig = np.zeros_like(raw)
    sig[0] = alpha * raw[0]
    for k in range(1, len(raw)):
        sig[k] = sig[k - 1] + alpha * (raw[k] - sig[k - 1])
    sig += RNG.normal(0.0, noise, size=sig.shape)
    t = np.arange(len(sig)) * dt
    return t, sig


fig, axes = plt.subplots(1, 2, figsize=(14, 6))

# Statistical mode
pulse = make_pulse_response()
a_stat = EyeAnalyzer(ui=UI, mode="statistical", modulation="nrz")
a_stat.analyze(pulse, noise_sigma=0.005, jitter_rj=0.005, dt=DT)
a_stat.plot_eye(ax=axes[0], title="Statistical eye (NRZ, RC pulse, σ=5mV, RJ=0.005UI)", cmap="hot")

# Empirical mode
t, v = make_nrz_waveform()
a_emp = EyeAnalyzer(ui=UI, mode="empirical", modulation="nrz")
a_emp.analyze((t, v))
a_emp.plot_eye(ax=axes[1], title="Empirical eye (NRZ, 4000 bits, σ=20mV)", cmap="hot")

plt.tight_layout()
out = "/tmp/eyes_compare.png"
fig.savefig(out, dpi=150)
print(f"wrote {out}")

plt.figure()
plt.plot(t, v)
plt.show()