[time-nuts] Producing jitter with Phase Modulation

Dr Bruce Griffiths bruce.griffiths at xtra.co.nz
Mon Mar 19 06:25:27 EDT 2007


Bilal Amin wrote:
> Hi Everyone,
>
> Some days back I emailed on the group regarding the jitter in the sampling clock of ADC. I  have tried the phase modulation method for producing the jitter. 
> I used the HP 8648B Signal generator for this experiment. I modulated the RF wave (at 10 MHz) with noise using the modulating input of the Signal Generator. For noise I used a Noise gen. from General Radio Company. It has three options for frequency. 10K, 100K and 5 M Hz. 
> I observed the output using an oscilloscope. The output wave form was jittery. BUT when changed the noise from 5M to 100K there was an increase in jitter.  Can any one help me out there, why this is happening? According to my understanding decreasing the bandwidth of noise  results in decrease in jitter as well. 
> Also I want to calculate the jitter at the output. i.e. the amount of noise I am adding. I think I wont be able to do it over the oscilloscope. Any ideas ?
>
> Regards
>
> Bilal
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>   
Bilal

The 8648B phase modulation input has a bandwidth of 10Hz to about 10kHz.

The resultant phase modulation dependency on the noise generator 
settings depends on the noise generator specifications.
What was the noise generator model, or can you provide a circuit diagram 
so the effect of the noise generator settings can be deduced?

Bruce




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