Hi It’s close in noise in the case of the HCT series parts.
Bob On Apr 29, 2014, at 3:13 AM, Magnus Danielson <[email protected]> wrote: > Alex, > > Sure, but is that close-in phase-noise or wideband white noise? > It matters greatly how it is distributed in frequency. > > Most importantly, is it low enough to recover the clock. > > If it is too high, then one needs to use another VCO. > > In this case, he only wanted to use the 74HCT9046 as a phase comparator and > then steer a VCXO, so the 9046s VCO phasenoise would not be relevant. > > The clock recovery PLL only have to have decent phase noise above 8 kHz, as > below that it is being suppressed by the loop and replaced by the source (and > lower frequency systematics from cabling and ISI). Sure, near 8 kHz it needs > to be decent as the suppression isn't perfect. > > Then comes the much narrower PLL. > > Cheers, > Magnus > > > On 04/29/2014 02:21 AM, Alexander Pummer wrote: >> the CMOS chip: PLL 74HC4046, 7046, 9046, will have substantial phase >> noise, particularly close to the higher end of the usable frequency range.. >> 73 >> Alex >> >> 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 <[email protected]> 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 >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
