PCM vs DSD. Why DSD and its variants?

[Orb]

Nearly there, Frank... It is not "at most" 9N, some are lower than that. The math says for a single-tone input the maximum (highest) spur is 9N dB down, so most are actually a little lower. The rest you have right.

Orb, somebody with a better psycho-acoustics background will have to address SNR vs. SFDR, but I will comment that we can pull out signals below the noise floor, and that includes distortion so would argue SFDR can in fact be important in audio as in other applications.

Again agree with you Don
My point was specific to the 16 bit signal that only has a boundary range of 96db when converted using the formula of linear value to decibels.
In this case, on a very good 16-bit replay system - CD (say with S/n around 110dba), it might be worth explaining how the signal is below the noise floor for CD.
Although more on topic is how interesting the spur can change with frequency.

Cheers
Orb

 

[Orb]

Got a handle on it now, Don. As you say, an individual spur or one specific harmonic is down by the 9N figure at the most, and that's very relevant for communication technology, but the actual noise is an enormous swath of spurs which add up to the 6N. As far as your ear if concerned that that one spur is so far down is pretty meaningless because it still can hear all the multitudes of other spurs all adding up, so it's only relevant for communications that you get this sort of performance with devices.

Frank

Was debating whether this was the right thread to share this paper I have, well fits with the current discussion so I guess might as well
http://www.analog.com/static/imported-files/tutorials/MT-003.pdf

Provides examples of the various specifications, and some of the lighter maths, and helps to put the measurement graphs into perspective by JA and PM.
Cheers
Orb

 

[fas42]

Nearly there, Frank... It is not "at most" 9N, some are lower than that. The math says for a single-tone input the maximum (highest) spur is 9N dB down, so most are actually a little lower.

Sorry, Don, I was being sloppy with language, I meant "at the most" in the sense you stated, must have been a bit tired when I put the sentence together ...

Frank

 

[Orb]

Just realised page 1 may put people off that article I linked, ignore that page and go straight to page 2 and read from there onwards.
Definitely worth reading; title is "Understand SINAD, ENOB, SNR, THD, THD + N, and SFDR so You Don't Get Lost in the Noise Floor"
Edit:
It is a useful reference as it shows a real-world 12-bit and also 14-bit ADC with measurement graphs and markers for full scale signal (page2),noise floor that is much lower, harmonics and thd, and example of spur with sfdr, along with values to the specifications (page 4 is 14-bit ADC), although we as consumers are interested in digital signal (the audio data) and DAC solution.
Cheers
Orb