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flykhan
2026-05-03 11:47:30 +08:00
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<text x="350" y="22" fill="#333" font-size="14" font-weight="bold" text-anchor="middle">Short-Time Fourier Transform (STFT) and Spectrogram</text>
<!-- ===== LEFT: Time-domain waveform ===== -->
<text x="120" y="48" fill="#333" font-size="11" font-weight="bold" text-anchor="middle">Time Domain</text>
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<text x="87" y="218" fill="#f39c12" font-size="8">w2</text>
<text x="112" y="218" fill="#27ae60" font-size="8">w3</text>
<text x="137" y="218" fill="#9b59b6" font-size="8">w4</text>
<text x="120" y="232" fill="#666" font-size="8" text-anchor="middle">overlapping windows</text>
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<text x="273" y="132" fill="#3498db" font-size="9" font-weight="bold" text-anchor="middle">FFT</text>
<text x="273" y="152" fill="#3498db" font-size="8" text-anchor="middle">per frame</text>
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<text x="470" y="48" fill="#333" font-size="11" font-weight="bold" text-anchor="middle">Spectrogram</text>
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<text x="475" y="238" fill="#666" font-size="9" text-anchor="middle">Time (frames)</text>
<text x="310" y="140" fill="#666" font-size="9" text-anchor="middle" transform="rotate(-90, 310, 140)">Frequency</text>
<!-- Spectrogram grid: coloured rectangles at different opacities -->
<!-- Row heights: each ~16px, 10 rows from y=60 to y=220 -->
<!-- Columns: ~12 columns from x=320 to x=620, each 25px wide -->
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<!-- Intensity legend -->
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<text x="655" y="90" fill="#666" font-size="7">high</text>
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<text x="655" y="120" fill="#666" font-size="7">low</text>
<!-- Frequency labels on y-axis -->
<text x="316" y="68" fill="#666" font-size="8" text-anchor="end">8 kHz</text>
<text x="316" y="140" fill="#666" font-size="8" text-anchor="end">4 kHz</text>
<text x="316" y="218" fill="#666" font-size="8" text-anchor="end">0 Hz</text>
<!-- Bottom note -->
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<text x="350" y="274" fill="#333" font-size="10" text-anchor="middle">STFT: slide a window along the signal, compute FFT of each frame.</text>
<text x="350" y="286" fill="#666" font-size="9" text-anchor="middle">Darker cells = more energy at that time-frequency bin</text>
</svg>
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