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20/20 AD User Guide Using the 20/20 AD

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Plot of noise + distortion vs. frequency for the 20/20 AD in 2- channel mode with a -60dBfs sinewave at 1kHz.

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WIDE dither is added before truncation. Noise floor is ele- vated further, but harmonic distortion is removed.

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PONS dither. Noise floor is down almost to the untruncated level in the critical band (2-4kHz), but significantly increased at high frequencies.

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20/20 AD in 2-channel mode, truncated to 16 bits without dither. Note harmonic distortion (spikes at multiples of 1kHz) and elevated noise floor.

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HF dither is added before truncation. Noise floor in audio range is lowered by 3dB — at the expense of increased noise above 20kHz.

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20BIT dither is added before truncation. This is similar to HF dither, but at a lower level. The dither reduces spurious tones (low-level spikes visible in the first plot) at the expense of a slightly elevated noise floor.

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