Re: [LAU] open hw soundcard (was Re: status usb2 for sound)

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From: <fons@...>
To: <linux-audio-user@...>
Date: Friday, November 13, 2009 - 9:41 pm

On Fri, Nov 13, 2009 at 07:56:13PM +0000, Folderol wrote:

> The effect you can get with a system with poor stability but very strong

- To generate a clock that is good enough for audio sampling you'll
need a analog PLL based on an Xtal oscillator, and with less than
1ns (nanosecond) jitter in the audio BW, and preferably even less.

- All AD converters require a clock that is much higher than
the sample frequency. For example the TI ADS1278 requires
27 or 37 MHz.

- If you want the soundcard to lock to a reference provided by
the master (PC), all you have is the timing of Ethernet
messages. For example the PC could send a message every
millisecond. With the above clock frequencies that would
mean a PLL multiplier with a ratio of 27000:1, somewhat
more than the 1:1 you seem to assume. It would need a BW
of a fraction of a second. Can be done, but not simple.

Ciao,

--
FA

Io lo dico sempre: l'Italia è troppo stretta e lunga.

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Messages in current thread:
[LAU] status usb2 for sound, Hartmut Noack, (Thu Nov 5, 9:06 am)
Re: [LAU] status usb2 for sound, Paul Davis, (Thu Nov 5, 2:45 pm)
Re: [LAU] status usb2 for sound, Lorenzo, (Thu Nov 5, 3:07 pm)
Re: [LAU] status usb2 for sound, Jörn Nettingsmeier, (Thu Nov 5, 3:40 pm)
Re: [LAU] status usb2 for sound, Hartmut Noack, (Thu Nov 5, 10:40 pm)
Re: [LAU] status usb2 for sound, Jörn Nettingsmeier, (Fri Nov 6, 9:19 am)
Re: [LAU] status usb2 for sound, Florian Faber, (Fri Nov 6, 9:28 am)
Re: [LAU] status usb2 for sound, Arnold Krille, (Sat Nov 7, 10:05 am)
Re: [LAU] status usb2 for sound, Ken Restivo, (Sun Nov 8, 7:49 am)
Re: [LAU] status usb2 for sound, Karl Hammar, (Sun Nov 8, 12:02 pm)
Re: [LAU] status usb2 for sound, Folderol, (Sun Nov 8, 2:46 pm)
Re: [LAU] open hw soundcard (was Re: status usb2 for sound), , (Fri Nov 13, 9:41 pm)
Re: [LAU] open hw soundcard, Karl Hammar, (Fri Nov 13, 5:10 pm)
Re: [LAU] open hw soundcard, Karl Hammar, (Fri Nov 13, 4:43 pm)
Re: [LAU] status usb2 for sound, Patrick Shirkey, (Sun Nov 8, 8:13 am)
Re: [LAU] status usb2 for sound, Florian Faber, (Sat Nov 7, 9:15 pm)
Re: [LAU] status usb2 for sound, Hartmut Noack, (Sat Nov 7, 11:06 am)
Re: [LAU] status usb2 for sound, Paul Davis, (Sat Nov 7, 6:47 pm)
Re: [LAU] status usb2 for sound, Hartmut Noack, (Sat Nov 7, 11:40 pm)
Re: [LAU] status usb2 for sound, Arnold Krille, (Sat Nov 7, 2:14 pm)
Re: [LAU] status usb2 for sound, Clemens Ladisch, (Fri Nov 6, 7:53 am)
Re: [LAU] status usb2 for sound, Ivica Ico Bukvic, (Sat Nov 7, 3:08 am)
Re: [LAU] status usb2 for sound, Clemens Ladisch, (Tue Nov 10, 1:57 pm)
Re: [LAU] status usb2 for sound, Arnold Krille, (Thu Nov 5, 11:38 pm)
Re: [LAU] status usb2 for sound, Martin Homuth-Rosemann, (Fri Nov 6, 6:55 pm)
Re: [LAU] status usb2 for sound, Dominic , (Sat Nov 7, 5:48 pm)
Re: [LAU] status usb2 for sound, Martin Homuth-Rosemann, (Sun Nov 8, 3:54 pm)
Re: [LAU] status usb2 for sound, Dominic , (Mon Nov 9, 12:20 am)
Re: [LAU] status usb2 for sound, david, (Sat Nov 7, 9:11 pm)
Re: [LAU] status usb2 for sound, Giso Grimm, (Thu Nov 5, 3:01 pm)