Dsp 1u

TDM/measure.sh

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+#!/bin/bash
+
+set -e
+HOST=nonos-4
+
+DIR=$(dirname $0)
+NAME=$1
+
+if [ -z "$NAME" ]; then
+    NAME=in
+fi
+
+Fs=48000
+T=60
+FMT=S32_LE
+DEV="CARD=sndrpigooglevoi,DEV=0"
+CH=2
+
+Tr=$((T - 5))
+
+TMPWAV=/tmp/tone.wav
+TMPIN=/tmp/in.wav
+
+sox -n -r $Fs -b 32 -c $CH $DIR/tone.wav synth $T sine 996.826 vol -3dB
+rsync $DIR/tone.wav $HOST:$TMPWAV
+
+ssh $HOST "aplay -D hw:$DEV -r $Fs -f $FMT -c $CH $TMPWAV" &
+ssh $HOST "arecord -D hw:$DEV -r $Fs -f $FMT -c $CH -d $Tr $TMPIN"
+
+rsync $HOST:$TMPIN $DIR/$NAME.wav
+
+uv run --script measure_tdm.py $DIR/$NAME.wav

TDM/measure_tdm.py

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+#!uv run --script
+# /// script
+# dependencies = [
+#   "numpy",
+#   "soundfile",
+#   "typer",
+# ]
+# ///
+
+"""
+Measure THD+N of a captured audio file.
+"""
+
+from pathlib import Path
+import numpy as np
+import soundfile as sf
+import typer
+
+
+def thd_thdn(x, fs, f0_hint=1000.0, bw=(20, 20000), max_h=10, nb=5):
+    # x can be (N,) or (N,C)
+    x = np.asarray(x)
+    if x.ndim == 2:
+        rms = np.sqrt(np.mean(x**2, axis=0))
+        x = x[:, int(np.argmax(rms))]
+    assert np.isfinite(x).all(), "Input has NaNs/Inf"
+    x = x - np.mean(x)
+
+    # pick N (power of two, not larger than input)
+    N = 1 << (len(x) - 1).bit_length()
+    if N > len(x):
+        N >>= 1
+    x = x[:N]
+    if N < 4096:
+        raise ValueError("Not enough samples")
+
+    w = np.hanning(N)
+    X = np.fft.rfft(x * w)
+    freqs = np.fft.rfftfreq(N, 1 / fs)
+    P = np.abs(X) ** 2  # consistent power units for ratios
+
+    # bandlimit
+    bw_lo, bw_hi = bw[0], (bw[1] if bw[1] is not None else fs / 2)
+    inband = (freqs >= max(20, freqs[1])) & (freqs <= bw_hi)
+
+    # find fundamental near hint (±5%)
+    kband = (freqs >= 0.95 * f0_hint) & (freqs <= 1.05 * f0_hint)
+    if not np.any(kband):
+        kband = inband
+    k0 = np.flatnonzero(kband)[np.argmax(P[kband])]
+
+    # integrate the fundamental mainlobe (±nb bins)
+    kf0_lo = max(0, k0 - nb)
+    kf0_hi = min(len(P), k0 + nb + 1)
+    V1p = np.sum(P[kf0_lo:kf0_hi])
+    if V1p <= 1e-24:
+        raise ValueError("Fundamental too small or not found.")
+
+    # THD: sum power in harmonic mainlobes (within Nyquist & band)
+    harm_p = 0.0
+    f0 = freqs[k0]
+    for k in range(2, max_h + 1):
+        fk = k * f0
+        if fk >= fs / 2 or fk > bw_hi:
+            break
+        hk = np.argmin(np.abs(freqs - fk))
+        lo = max(0, hk - nb)
+        hi = min(len(P), hk + nb + 1)
+        harm_p += np.sum(P[lo:hi])
+
+    THD = np.sqrt(harm_p) / np.sqrt(V1p)
+
+    # THD+N: everything in band except the fundamental mainlobe
+    residual = inband.copy()
+    residual[kf0_lo:kf0_hi] = False
+    # (optional) notch mains:
+    for hz in (50, 60, 100, 120, 150, 180):
+        j = np.argmin(np.abs(freqs - hz))
+        residual[max(0, j - 1) : min(len(P), j + 2)] = False
+
+    THDN = np.sqrt(np.sum(P[residual])) / np.sqrt(V1p)
+
+    thd_db = -np.inf if THD == 0 else 20 * np.log10(THD)
+    thdn_db = -np.inf if THDN == 0 else 20 * np.log10(THDN)
+
+    fund_dbfs = 20 * np.log10(
+        np.sqrt(np.sum(np.abs(X[kf0_lo:kf0_hi]) ** 2))
+        / (np.sqrt(np.sum(np.abs(X) ** 2)) + 1e-20)
+    )
+    noise_dbfs = 20 * np.log10(
+        np.sqrt(np.sum(P[residual])) / (np.sqrt(np.sum(np.abs(X) ** 2)) + 1e-20)
+    )
+    print(f"Fund ~{fund_dbfs:.1f} dBFS, Residual ~{noise_dbfs:.1f} dBFS")
+
+    sinad_db = -20 * np.log10(THDN)  # same bandwidth as THD+N
+    enob = (sinad_db - 1.76) / 6.02
+    print(f"SINAD {sinad_db:.1f} dB, ENOB {enob:.2f} bits")
+
+    return THD, thd_db, THDN, thdn_db
+
+
+def main(file: Path):
+    x, fs = sf.read(file, always_2d=True)
+    x = x[:, 0]
+    THD, thd_db, THDN, thdn_db = thd_thdn(x, fs, f0_hint=997.0, bw=(20, 20000))
+    print(THD, thd_db, THDN, thdn_db)
+
+
+if __name__ == "__main__":
+    typer.run(main)

firmware/dsp_server/README.md

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+# Setup
+
+```bash
+# rsync nonos_server to nonos
+rsync -a dsp_server nonos:
+ssh <pi_hostname> "cd dsp_server && ./setup.sh"
+```
+
+## Bluetooth
+
+Enable `FastConnectable=y` in `/etc/bluetooth/main.conf`
+Make pairable and trust all devices:
+
+Not sure about those:
+
+```
+[General]
+AutoEnable=true
+Class = 0x200414
+DiscoverableTimeout = 0
+PairableTimeout = 0
+JustWorksRepairing = always
+```
+
+# Broken
+
+- bluetooth only works after login with ssh
+- vnc stuff, see setup.sh (needs manual vncpasswd set)
+