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Old 7th February 2013, 09:08 AM   #2331
Bunpei is offline Bunpei  Japan
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It's a great measurement result!

Quote:
Originally Posted by iancanada View Post
Frequency: 98.3097MHz
N = 10,000 cycles
Sampling at 8GS/s
Would you reply to my primitive questions?
Please feel free to ignore those. I know very well that you are too busy.

1. In an example datasheet of oscillator devices, like this,
7311S-DF-255R(Fixed Communication)/Simple Packaged Crystal Oscillator (SPXO)/NDK
here we find such a description;
> Phase jitter (RMS) Max. 1 ps(12kHz to 20MHz)

Does your measurement give the frequency range condition as well?
The reason why I ask this is that I want to apply an apple-to-apple comparison.

2. Does the "N = 10,000 cycles" mean that your histogram and statistical calculation results are based on 10,000 sample pulses?
How many raw sampling points of which sampling frequency are used for the internal calculation in your LeCroy digital oscilloscope?

3. When we look at phase noise measurement charts, dBc/Hz values within 1-100 Hz range show big differences in general. Is your jitter histogram equivalent or does it cover the same frequency range?
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Old 7th February 2013, 09:56 AM   #2332
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no, Ian measures period jitter not phase.
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Old 7th February 2013, 01:26 PM   #2333
Bunpei is offline Bunpei  Japan
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Quote:
Originally Posted by Nazar_lv View Post
no, Ian measures period jitter not phase.
Hi, Nazar_lv,

Thank you very much for your advice.
Would you tell me the difference between a period jitter and a phase jitter in spite of the same unit [ps RMS] if you have enough time or you know a good web pages that explain the difference in plain words?

Bunpei
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Old 7th February 2013, 05:34 PM   #2334
glt is offline glt  United States
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Quote:
Originally Posted by Bunpei View Post
Hi, Nazar_lv,

Thank you very much for your advice.
Would you tell me the difference between a period jitter and a phase jitter in spite of the same unit [ps RMS] if you have enough time or you know a good web pages that explain the difference in plain words?

Bunpei
Bunpei, you may review this: Jitter Specification: a Summary H i F i D U I N O :-) (I don't claim this is definitive, just based on my limited best understanding)

I think phase jitter RMS = 10 x period jitter pp, but pp needs to measured for a larger sample according to industry standards...

Correction: 10,000 is industry standard...

So phase noise jitter RMS=2.4psec (pp being +/-12 or 24)
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Last edited by glt; 7th February 2013 at 05:48 PM.
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Old 8th February 2013, 08:55 AM   #2335
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Hi Bunpei, sorry my time is very limited

Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter
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Old 8th February 2013, 04:10 PM   #2336
Bunpei is offline Bunpei  Japan
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Hi, glt & Nazar_lv,

Thank you very much for your help!

I should have read glt's comprehensive explanation page before I posted my previous question on the difference of "Phase Jitter" and "Period Jitter".
Now I think I understand well that a "Phase Jitter [RMS ps]" value is quite different from a "Period Jitter [RMS ps]" value and those two kind of values can't be compared directly.

In order to have a better understanding of the range coverage gap between "Phase Noise Graph" and "Period Jitter Histogram", I made a table as shown below.
The notation "d" is a deviation in a frequency domain and "Period" and "Period Jitter" are representation in a time domain.


_d[Hz]____d[ppm]_Freq[MHz]__Period[ps]__Period Jitter[ps]
-115900 -1179.00 98.188100 10184.533564 12.007522
_-37200 _-378.42 98.266800 10176.376966 +3.850924
_-10000 _-101.73 98.294000 10173.560950 +1.034908
__-1000 __-10.17 98.303000 10172.629523 +0.103481
___-100 ___-1.02 98.303900 10172.536390 +0.010348
____-10 ___-0.10 98.303990 10172.527076 +0.001035
_____-1 ___-0.01 98.303999 10172.526145 +0.000103
______0 ____0.00 98.304000 10172.526042 _0.000000
_____+1 ___+0.01 98.304001 10172.525938 -0.000103
____+10 ___+0.10 98.304010 10172.525007 -0.001035
___+100 ___+1.02 98.304100 10172.515694 -0.010348
__+1000 __+10.17 98.305000 10172.422562 -0.103479
_+10000 _+101.73 98.314000 10171.491344 -1.034698
_+37200 _+378.42 98.341200 10168.678031 -3.848010
+116300 +1183.06 98.420300 10160.505505 -12.020536


I think that the phase jitter measurement of ps order covers quite a different range from the phase noise 1-100Hz range.

To glt,
> I think phase jitter RMS = 10 x period jitter pp

Is the following expression correct?
phase jitter RMS = 0.1 x period jitter pp

Bunpei
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Old 8th February 2013, 08:14 PM   #2337
glt is offline glt  United States
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Quote:
Originally Posted by Bunpei View Post
Hi, glt & Nazar_lv,...
To glt,
> I think phase jitter RMS = 10 x period jitter pp

Is the following expression correct?
phase jitter RMS = 0.1 x period jitter pp

Bunpei
Oops, Yes :-)
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Old 8th February 2013, 09:15 PM   #2338
1audio is offline 1audio  United States
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Without knowing the composition of the jitter/phase noise you really cannot arbitrarily map one to the other.

Also cycle to cycle jitter, which is very relevant to moving data may not show any low frequency components. I have tried measuring jitter on an FM modulated signal (+/- 100 KHz on 10 MHz and got less than 25 pS of jitter.

For DAC/ADC clocking you really need to look at the spectrum from 100 Hz (AES or really 20 Hz) to the max bandpass of the system. Beyond really doesn't matter much. The best way of course is in the audio output since that is what really matters.
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Old 9th February 2013, 10:36 PM   #2339
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Default For the TDA1541 fans...

I posted this over in Oliver's (dvb-projekt) DAC forum.

"Reference" TDA1541A DAC with I2S-BUS architecture

Ian...this is truly a game changer. Thanks.
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Old 10th February 2013, 04:35 AM   #2340
karvid is offline karvid  Sweden
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I just started my BIIIse together with the Asynchronous I2S FIFO and a dual Clock board.
When I try 192kHz Music and with the MLCK instead of the BIII onboard 100MHz oscillator the BIII don't get a locked signal. I still havn't changed any of the oscillators included in the dual Clock board kit. (with 44.1kHz Music it works great).

It works perfect it I disconnect MLCK and uses the BIII Clock and only the I2S signal from the dual Clock board.

What could be the problem?

Also do anyone have recommendations on what Clocks to use for best performance out from the dual Clock board?


Thanks
Kenneth
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