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26th December 2008, 10:26 #1
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clock ppm
anyone tell me "clock frequency is 50MHz+/50ppm?" what is really frequency?
(50M+ 50/1,000,000)Hz? or (50M  50/1,000,000)Hz?
50/1,000,000 is very small ,almost can be ignored . I think.

26th December 2008, 10:26

26th December 2008, 10:36 #2
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ppm clock
You are right but this small time when accumulated over years then it creates an error of second per say.
Some people may not interested in this error too.
For the above calculation the frequency will lie between the two possible frequencies.

26th December 2008, 10:48 #3
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clock ppm calculation
50 ppm at 50 MHz means a deviation of 2.5 kHz, an amount that isn't really small for a lot of applications.
For a watch, 50 ppm implies an error of 26 minutes per year, for an UHF small band radio device, it would be considerably above tolerated error limits.

26th December 2008, 10:48

2nd January 2009, 04:21 #4
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clock ppm calculator
if the samle frequency and different ppm in write clock and read clock ,Anyone can tell me how to calculate fifo depth ?

2nd January 2009, 04:21

2nd January 2009, 08:00 #5
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clock frequency ppm
hi feel_on_on
i think if you meet case that different ppm in write clock and read clock, u have to consider worse case to calculate fifo depth.
littlebu

6th January 2009, 05:41 #6
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how to compute ppm in clocks
if read clock is 50Mhz+/50ppm,write clock is 50Mhz+/50ppm ,but they is the different clock . please tell me how to think about the fifo depth?
Added after 1 hours 57 minutes:
forget to speak ,the MAX transmit Unit is 1500 bytes

6th January 2009, 05:53 #7
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what is clock ppm
Originally Posted by FvM

6th January 2009, 05:53

6th January 2009, 07:41 #8
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50ppm
50e6*50e6=2500

16th February 2011, 01:34 #9
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Re: clock frequency is 50MHz+/50ppm?
Here is how to calculate
Convert ppm to Hz
50 MHz nominal +/50 ppm
(50000000 / 1000000)*50 = +/ 2500 Hz which define the frequency bound of
the oscillator to 49.9975 MHz <= f <= 50.0025 MHz
Hope this will help

26th July 2012, 08:00 #10
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Re: clock frequency is 50MHz+/50ppm?
Friends check this link for PPM to Hz and vice  versa conversion:
http://www.jittertime.com/resources/ppmcalc.shtml
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