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Location: Muizen (Belgium)
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Setting jumper TXSRC high and feeding a 12.000MHz clock to the clock connection block?
Or would it be wiser to remove the crystal and feeding the external clocksignal to pin 11?
Anyone tried an external clock on the receiver and found/measured better results?
--> Is the intrinsic period jitter of 50 ps RMS measured by feeding a super low jitter low noise
clock into the chip, or are we talking 50 ps RMS, regardless of the used clock?!
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Rank: Member
Groups: Member
Joined: 9/9/2007(UTC)
Posts: 11
Location: Muizen (Belgium)
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OneyedK wrote:
Or would it be wiser to remove the crystal and feeding the external clocksignal to pin 11?
Whoops, figured that one out myself, you really have to remove the crystal and caps... Still no answer to my other questions?!
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Rank: Member
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Posts: 6
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OneyedK wrote:Anyone tried an external clock on the receiver and found/measured better results?
--> Is the intrinsic period jitter of 50 ps RMS measured by feeding a super low jitter low noise
clock into the chip, or are we talking 50 ps RMS, regardless of the used clock?! I would ask the same questons.... For sure output jitter is related to the input clock jitter, but how good clock should really be?! If the intrinsic jitter of the WM8804 is 50ps (and if you look at its internals) I guess it does not make sense to use ultra low jitter clock... does anybody have data on "default" crystal jitter, used on SPDIF board? I've went quickly through WM8804 datasheet and I think the chip just is not able to be a low (< 50ps) jitter source. I will now study Metronome if it can handle the job right ;) - Matej
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I don't know enough about the internals of the Wm8804 to answer some of the questions. Your best bet is to contact Wolfson.
But yes, you if want to use an external clock you need to remove the on-board clock.
You will also need to run the chip in software mode if you don't want to use a 12mhz clock. The version 1.0 boards were not design for software mode, though the version 2.0 boards do support it.
Cheers!
Russ
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