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Old 12th September 2006, 11:31 PM   #1
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Default non os measurement

This is about a partially filtered non os DAC.

First, music signal from an oversampling CD player, 31 kHz analyzer bandwith.
It can be seen the CD bandwith limitation of 22,5 kHz.

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Now the transformer + cap filtered non os DAC.
The empty space above 22,5 kHz is filled with harmonics.
Non os gives back a little of what the CD format has taken away.

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Pink noise from CD with oversampling, 83 kHz analyzer bandwith.

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Pink noise from CD with non os DAC.
It can be seen, at 80 kHz HF is pretty much down.
That should not be a problem for a good amplifier.

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Old 13th September 2006, 12:50 AM   #2
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1 kHz full scale sine non os.
There is the rest of the HF visible.

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FFT of the sine, analyzer bandwith 10 kHz, 94dB vertical scale.
The k2 harmonic is caused by the passive I/V.

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Same with 100 kHz analyzer bandwith, the 44,1kHz and 88,2 kHz are split, jitter

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Old 13th September 2006, 06:24 AM   #3
Werner is offline Werner  Europe
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Quote:
Originally posted by Bernhard
The empty space above 22,5 kHz is filled with harmonics.
Non os gives back a little of what the CD format has taken away.
These aren't harmonics, and thus these aren't what 'the CD format has taken away'.


Quote:
Originally posted by Bernhard
Same with 100 kHz analyzer bandwith, the 44,1kHz and 88,2 kHz are split, jitter

Baseband frequency f creates images at every N*fs+f and N*Fs-f,
so 1kHz has images at
44.1kHz-1kHz
44.1kHz+1kHz
88.2kHz-1kHz
88.2kHz+1kHz
...
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Old 13th September 2006, 09:12 PM   #4
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Quote:
Originally posted by Werner

Baseband frequency f creates images at every N*fs+f and N*Fs-f,
so 1kHz has images at
44.1kHz-1kHz
44.1kHz+1kHz
88.2kHz-1kHz
88.2kHz+1kHz
...
Thanks

Still, there is something above 22 kHz and maybe it makes a difference. Perhaps.
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