[time-nuts] 74HCT9046A Max. Operating Frequency

Alexander Pummer alexpcs at ieee.org
Mon Apr 28 20:21:37 EDT 2014

the CMOS chip: PLL 74HC4046, 7046, 9046,  will have substantial phase 
noise, particularly close to the higher end of the usable frequency range..

On 4/28/2014 1:30 PM, Magnus Danielson wrote:
> Chris,
> On 04/28/2014 04:16 PM, Chris Albertson wrote:
>> On Sun, Apr 27, 2014 at 11:41 PM, sg sg <micpreamp at yahoo.de> wrote:
>>> Thanks very much for your responses!
>>> ..
>>> The source is an AK4114 AES/EBU audio receiver, which has both master
>>> clock (24.576 MHz) and "word select" rate (48-192 kHz) outputs. 
>>> Perhaps it
>>> is better to run the PLL at the latter? Any disadvantages from this?
>> So this is for clock distribution in a studio?   While our eras don't 
>> care
>> about nano seconds or even micro seconds we do care that long of the 
>> same
>> length have exactly the same number of samples.  In other words at a 
>> given
>> times into a track, all tracks have the same number of samples.    I 
>> think
>> what matters in this application is long term stability over days, weeks
>> and even years.   So the first step is always to figure out your
>> requirements and USE NUMBERS.
>> Next.  It is not "either/or"  you can put the PPL at 24..5MHz or 48K 
>> or you
>> can divide by 10 and put the PPL at 2.45Mhz.  or any place in between.
>> One question:  Why use the receiver as a clock source?  Most use 
>> something
>> independent like an OX or even Rb then use that to drive a DDS chip.
> Rb is way overkill. Beyond keeping things in sync to ensure same 
> sample rate, what is important is jitter but not ppm level wander.
> Jitter can kill your listening experience by to ways, one is bit error 
> rate, causing bits to be incorrect. The second is that it creates 
> side-bands, which causes issues when you try to achieve 24 bit 
> resolution, or for that matter 130 dB dynamics. Do read what Julian 
> Dunn had to discuss on that matter, since he look at what sidebands 
> would do, considering masking effects of psycho-acoustics etc.
> Then again, we being time-nuts, overkill is easy to achieve.
> We need to be careful about jitter as we re-synthesize and lock things 
> up. Jitter-peaking as a cause of jitter accumulation, and that leads 
> to... bit errors and side-bands.
> Cheers,
> Magnus
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