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From: gibson@unc.UUCP
Newsgroups: sci.electronics
Subject: Re: Phase Jitter of a free-running oscillator
Message-ID: <919@unc.unc.UUCP>
Date: Sat, 14-Feb-87 13:27:40 EST
Article-I.D.: unc.919
Posted: Sat Feb 14 13:27:40 1987
Date-Received: Tue, 17-Feb-87 05:49:23 EST
References: <5246@reed.UUCP>
Reply-To: gibson@unc.UUCP (Bill Gibson)
Organization: CS Dept, U. of N. Carolina, Chapel Hill
Lines: 26

In article <5246@reed.UUCP> mdr@reed.UUCP (Mike Rutenberg) writes:
>What is the "phase jitter of a free-running oscillator" and what does it
>depend on?  Does anyone have any revealing references?

I'm not sure what your context is, but the only context in which I've
seen that phrase is in digital oscillators. If you use a digitally-
stored waveform and sequence through its points to generate a waveform
(sending each point to a DAC), I know of 2 definitions :

1) sample period jitter - unevenness in time between output samples.
    The reference implies noise from this jitter is 83 dB below the
    RMS level of a generated sine wave  iff the sample period jitter
    is < (0.0000118 / F) (sec), where F is the output frequency.
    "Design of a digital oscillator...", John Snell, Computer Music
    Journal 1(2):4-25, 1977

2) phase jitter - errors due to finite length of the stored waveform.
    If you use a 256-point table and a 16-bit phase register, you
    will get noise because the 8-bit address and the 16-bit phase 
    often refer to different points on the waveform (since the phase
    must be truncated or rounded).
    "Table Lookup Noise...", Richard
    Moore, Computer Music Journal 1(2):26-29, 1977

Bill Gibson
gibson@unc                   ...[akgua,decvax,philabs]!mcnc!unc!gibson