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rkdrkd
Joined: 15 Jul 2004
Posts: 56
Helped: 3
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 02 Aug 2004 5:24 What is Jitter??? |
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Can someone guide me about te term "Jitter"??
Is it the same as Noise???
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delay
Joined: 11 Jun 2004
Posts: 219
Helped: 3
Location: Van Allen Belt
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| 02 Aug 2004 6:53 Re: What is Jitter??? |
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It is the variation in frequency or time such as if the data packets do not follow a tight time bound or a clock frequency changes back and forth but centers around a normal value you say clock is jittery.
Depending on the situation such as in clock domains, jitter can result in malfunction or noise. However, data networks where you tend to experience delays due to jitter will hardly be ever attributed to noise.
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rauol
Joined: 02 Oct 2002
Posts: 364
Helped: 11
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| 02 Aug 2004 9:24 Re: What is Jitter??? |
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Jitter is also added in the clock deliberately to Pass EMI regulations.
Due to jittering The noise spectrum will be distributed .
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fivaro1
Joined: 26 May 2001
Posts: 50
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| 08 Sep 2004 7:41 Re: What is Jitter??? |
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Jittes is a (usually small and rapid) fluctuation in a
phenomenon, such as a quantity or wave, because
of noise, mechanical vibration, interfering
signals, or similar internal or external disturbances.
Noise is a random-frequency current or voltage
signal extending over a considerable frequency
spectrum and having no useful purpose, unless
it is intentionally generated for test purposes.
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JoseLeonardo
Joined: 09 Aug 2004
Posts: 107
Helped: 4
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| 09 Sep 2004 16:17 What is Jitter??? |
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| Jitter are a set of variations of frecuency on the oscillators of very high speed, what causing a considerable degradations on the receptions process.
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Andre3000
Joined: 25 Aug 2004
Posts: 18
Helped: 2
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| 09 Sep 2004 21:40 What is Jitter??? |
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| is a rapid variations in a signal due to electric disturbance.
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Big Boy
Joined: 20 Jan 2004
Posts: 253
Helped: 10
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| 10 Sep 2004 23:40 Re: What is Jitter??? |
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Jitter, when talking abour 'frequency' jitter, can be seen as follow.
Imagine you have a 100MHz clock signal. You then have a period of 10ns (10 nanosecond). Now, if you would have a device that could measure the time between each rising or falling edge of that signal, you would see that it take 10ns from a rising edge to the other raising edge, that is:
10ns, 10ns, 10ns, 10ns, 10ns, 10ns, ...
This would be a perfect (i.e. jitter-free) signal.
Now, imagine that when you measure that signal, you get the following results, for the time between each raising edge of the signal:
10.1ns, 10ns, 9.9ns, 10ns, 10.1ns, 10ns, 9.9ns, 10ns, ...
It is clear that on a frequency meter, you would still see that the average signal is 100MHz, but that signal also does have what's called 'jitter'. I.e. it is constantly 'wobbling'.
Jitter can be either innoffensive, usefull or undesirable. This depend on the application. In telecom, where you pass a lot of information over a single line, jitter is really not desirable as this can create bit errors if too much jitter is present. In most applications, though, jitter is innoffensive (just pass unnoticed). In modern computers, jitter is intentionally used so that the EMI get reduced (instead of having a big EMI signal, the EMI is soften, spread across a wider bandwidth).
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madjid
Joined: 29 Aug 2004
Posts: 36
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| 11 Sep 2004 6:03 Re: What is Jitter??? |
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Hi,
Read the attachment.
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krashkealoha
Joined: 03 Jul 2004
Posts: 101
Helped: 7
Location: 21.402, -157.739
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| 11 Sep 2004 9:30 Re: What is Jitter??? |
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Attached is an apps note about jitter basics.
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savadi
Joined: 14 Sep 2004
Posts: 27
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| 23 Sep 2004 19:00 Re: What is Jitter??? |
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jitter is the variation of the frquency. suppose your clock frequency wolud be 1 GHz. if your frequency increses or decrese, your clock has jitter. the resean of jitter is noise. the most important nois is the power supply noise in mixed mode designs. thermal noise of devices which used in your circuit (transistor, resistor) is the other source of jitter.
Phase noise and EYE diagram is the econventional method to meassure your jitter .
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carrot
Joined: 23 Feb 2004
Posts: 172
Helped: 3
Location: Bangalore, India
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| 25 Sep 2004 13:37 Re: What is Jitter??? |
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hi
jitter is the sudden vibration or sudden variation in your working environment.
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yorande
Joined: 19 Jan 2004
Posts: 101
Helped: 1
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| 26 Sep 2004 5:00 Re: What is Jitter??? |
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| As I see in an article, it's just the Cyclostationary Noise in digital circuits..
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krashkealoha
Joined: 03 Jul 2004
Posts: 101
Helped: 7
Location: 21.402, -157.739
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| 06 Oct 2004 8:16 Re: What is Jitter??? |
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Here is another jitter paper dealing with the basics.
It's from April 2004, "High Frequency Electronics."
Jitter - Understanding it, Measuring it, Eliminating it
Part 1: Jitter Fundamentals
Part 2: Jitter Measurements
Part 3: Causes of Jitter
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golfbumb
Joined: 29 Sep 2004
Posts: 40
Helped: 5
Location: California
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| 06 Oct 2004 22:45 Re: What is Jitter??? |
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Jitter does not equal noise. Jitter is the deviation in phase frequency, amplitude, or phase width in an expected signal.
Noise is the superimposition of extra, generally unexpected signals, on top of the expected signal, that have an unpredictable value for any time t.
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