Bilal Amin wrote: > ----- Original Message ----- > From: "Dr Bruce Griffiths" <[EMAIL PROTECTED]> > To: "Discussion of precise time and frequency measurement" > <time-nuts@febo.com> > Sent: Friday, March 02, 2007 6:10 PM > Subject: Re: [time-nuts] External clock for Analog to Digital Converter in > GPS Rx front-end > > > >> Bilal Amin wrote: >> >>> Hi Everyone, >>> >>> I am working on Jitter in Analog to Digital Converters(ADCs) for GPS >>> receiver front-end. I am trying to setup an experiment to see the effects >>> of jitter in real time ADCs. I have an ADC evaluation board with external >>> clock input for sampling (i.e Sampling clock). Now I want to produce a >>> self created jittery signal to see the effects of jitter in ADC. Can >>> anyone out there have any idea(s) how I can produce a real time clock >>> signal with "variable jitter" for the input of external clock? Producing >>> a simple clock signal (i.e. without jitter) is straight forward with the >>> help of any signal generator but a clock signal with "variable jitter" is >>> a problem. >>> >>> Thanks for your help. >>> >>> Cheers >>> >>> Bilal >>> _______________________________________________ >>> time-nuts mailing list >>> time-nuts@febo.com >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> >>> >>> >> Bilal >> >> All you have to do is add sufficient noise to a sinewave clock. >> The clock shaping circuitry will then convert the noise to timing jitter >> at the zero crossings. >> All you need is a suitable source of wideband noise. >> >> Bruce >> >> _______________________________________________ >> time-nuts mailing list >> time-nuts@febo.com >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> >> > Hi Bruce, > > Thanks for your email.Adding noise to a sine wave is not that straight > forward I guess. Do you think a comparator works for this? > > > _______________________________________________ > time-nuts mailing list > time-nuts@febo.com > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > Bilal
You can easily add noise to a sinewave, for example a hybrid combiner can be used to combine the output of a sinewave generator and a noise source. It is also possible to connect a noise source to one input of a comparator whilst connecting the sinewave to the other input of the comparator. Selected current starved zeners can make very good wideband noise sources, buffer and amplify/attenuate as required. Bruce _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts