Pete, Thanks for your valuable information. You have explained exactly what is happening and I have got it finally. I have a digi. oscilloscope with a jitter measurement option, but it is only for square waveforms. Unfortunately the Sig. Gen. I am using has no option for square wave. I think I have to use a comparator to get the square wave form and then measure jitter with oscilloscope.
Cheers Bilal ----- Original Message ----- From: "Pete" <[EMAIL PROTECTED]> To: "Discussion of precise time and frequency measurement" <[email protected]> Sent: Tuesday, March 20, 2007 2:42 AM Subject: Re: [time-nuts] Producing jitter with Phase Modulation > Bilal, > > The GR noise generators were specified for total noise voltage in a > specified bandwidth. With the HP signal generator input limited to 10KHz, > your observation of increasing noise as the GR source bandwidth is reduced > is as expected. You are simply applying more of the GR's output to the HP > signal generator by better matching the source bandwidth to the "load". > > An oscilloscope is a difficult tool for the measurement you propose. If > that's what you must use, then get a storage 'scope or an equivalent > digital > 'scope which will allow you to integrate up the jittering waveform. This > is > essentially what folks do to create an "eye" diagram for estimating high > speed data link jitter. The difficulty with this approach is that the > probability observing maximum jitter is quite low & the 'scope waveform > tends to have very low intensity for these "rare" events, so it's tough to > know where the outer edges of the jitter are. The digital "scopes are > superior for this application, but rather expensive. > > Regards, > Pete Rawson > > > _______________________________________________ > time-nuts mailing list > [email protected] > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
