RME OctaMic II handleiding
Handleiding
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User’s Guide OctaMic II © RME
12. Word Clock
12.1 Operation and Technical Background
In the analog domain one can connect any device to another device, synchronisation is not nec-
essary. Digital audio is different. It uses a clock, the sample frequency. The signal can only be
processed and transmitted when all participating devices share the same clock. If not, the signal
will suffer from wrong samples, distortion, crackle sounds and drop outs.
AES/EBU, SPDIF and ADAT are self-clocking, an additional word clock connection in principle
isn't necessary. But when using more than one device simultaneously problems are likely to hap-
pen. For example any self-clocking will not work in a loop cabling, when there is no 'master' (main
clock) inside the loop. Additionally the clock of all participating devices has to be synchronous.
This is often impossible with devices limited to playback, for example CD players, as these have
no SPDIF input, thus can't use the self clocking technique as clock reference.
In a digital studio synchronisation is maintained by connecting all devices to a central sync source.
For example the mixing desk works as master and sends a reference signal, the word clock, to
all other devices. Of course this will only work as long as all other devices are equipped with a
word clock or sync input, thus being able to work as slave (some professional CD players indeed
have a word clock input). Then all devices get the same clock and will work in every possible
combination with each other.
Remember that a digital system can only have one master!
But word clock is not only the 'great problem solver', it also has some disadvantages. The word
clock is based on a fraction of the really needed clock. For example SPDIF: 44.1 kHz word clock
(a simple square wave signal) has to be multiplied by 256 inside the device using a special PLL
(to about 11.2 MHz). This signal then replaces the one from the quartz crystal. Big disadvantage:
because of the high multiplication factor the reconstructed clock will have great deviations called
jitter. The jitter of a word clock is much higher as when using a quartz based clock.
The actual end of these problems is offered by the SteadyClock technology of the OctaMic II.
Combining the advantages of modern and fastest digital technology with analog filter techniques,
re-gaining a low jitter clock signal of 22 MHz from a slow word clock of 44.1 kHz is no problem
anymore. Additionally, jitter on the input signal is highly rejected, so that even in real world usage
the re-gained clock signal is of highest quality.
Bekijk gratis de handleiding van RME OctaMic II, stel vragen en lees de antwoorden op veelvoorkomende problemen, of gebruik onze assistent om sneller informatie in de handleiding te vinden of uitleg te krijgen over specifieke functies.
Productinformatie
| Merk | RME |
| Model | OctaMic II |
| Categorie | Niet gecategoriseerd |
| Taal | Nederlands |
| Grootte | 3434 MB |
