User manual

8X96 ADC and DAC User Manual Page 48 of 54
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1. The lowest numbered bchan has the earliest-time sample.
2. The next-lowest bchan has the next-earliest sample, and so on.
3. The S/MUX channel (schan) sample rate is an integer multiple (N) of the bchan rate
(e.g. 2x, 3x, 4x,etc.)
4. The oversampling multiplier N is called the order of the schans, notated S/MUX N
(e.g. S/MUX 2 for a 2x, 48KHz to 96KHz system).
5. The first group of bchans {1..N} represent the first schan.
6. The second group of bchans {N+1..2N} represent the second schan, and so on.
7. Though any integer N can be used for the order, powers of two are recommended (2, 4,
8, 16, etc.)
8. No non-audio signaling will be present in the audio streams. Though this means the
user (or system) needs to make not of the S/MUX order, it also means maximum possible
fidelity (using every bit for audio data) as well as simplicity of implementation.
9. It is possible to use schans of different orders simultaneously though care should be
taken to avoid confusion.
10. S/MUX compatible systems must not filter the audio in any way. Since each channel
only sees a fraction (1/N) of the total schan data, any filtering would be invalid (e.g.
lowpass, bandpass, highpass filters).
11. Though ADAT lightpipe is the first implementation, the concept is applicable to any
digital audio format. In fact, the AES is working on a standard for just such a system
using AES/EBU streams.
12. S/MUX is compatible with dithering and gain changes, as long as they are done
exactly the same way for each bchan in a schan group. That is, you can dither or change
the gain of the schan by applying the processing uniformly to the bchans.