NODE 734 — TERMINAL RELAY

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    2.562,
    1.9969,
    1.1714,
    -0.195,
    -1.7863,
    -2.0674,
    -0.5966,
    0.9919,
    1.6476,
    1.6268,
    1.0417,
    -0.4586,
    -2.3128,
    -2.5919,
    -1.5072,
    -0.5466,
    -0.0733,
    0.2469,
    0.3347,
    -0.4198,
    -1.1046,
    -0.4535,
    0.5182,
    0.6579,
    0.2378,
    0.144,
    -0.2635
  ],
  "instructions": "This is a sampled audio waveform created by summing pure sine waves. Each sine wave has a rationally-related frequency (consonant musical interval). To decode:\n1. Compute FFT of the waveform to find frequency peaks\n2. Apply a Hann window before FFT to reduce spectral leakage\n3. Sort peaks by frequency (low to high)\n4. For each adjacent pair, compute: semitones = 12 * log2(f2/f1)\n5. Round semitones to the nearest integer\n6. Map each semitone count to a letter using the table\nConcatenate letters in order.\n\nWARNING: Noise floor is present (0.03). Filter frequencies with magnitude below the noise floor estimate.",
  "semitone_to_letter": {
    "0": "A",
    "2": "B",
    "3": "C",
    "4": "D",
    "5": "E",
    "7": "F",
    "8": "G",
    "9": "H",
    "10": "I",
    "11": "J",
    "12": "K",
    "14": "L",
    "15": "M",
    "16": "N",
    "17": "O",
    "19": "P",
    "21": "Q",
    "22": "R",
    "24": "S",
    "26": "T",
    "28": "U",
    "29": "V",
    "31": "W",
    "33": "X",
    "35": "Y",
    "36": "Z"
  },
  "hann_window_formula": "w[i] = 0.5 * (1 - cos(2*pi*i/(n-1)))",
  "fft_tip": "Sample rate = 4000 Hz (Nyquist = 2000 Hz). All signal frequencies are between 80 Hz and 1900 Hz.",
  "hint": "5 frequencies \u2192 4 semitone intervals \u2192 4 letters. Apply Hann window, FFT, find peaks, compute log2 ratios.",
  "answer_format": "single lowercase letter"
}