[SI-LIST] Re: Accounting random jitter

It seems that my inability to type the list address has stopped the original 
post going through.
 
I have included some points below for discussion.
 
All of the simulators mentioned are deterministic, be it MATLAB, SPICE etc. 
Each simulator has its own benefits, and may make it easier to create 
'representative' distributions. However, we shouldn't forget the behvioural 
constructs of SPICE.
Any noise distribution is likely to be distorted by sampling, whether 
experimentally or in a simulator.
 
My half pence worth, is to create a noise distribution offline e.g. using the 
bootstrap method. Then characterise it in an unbiased way. Now at least you 
have a representative deterministic noise distribution. 
The determinism is useful, because it will alow the recreation of results.
Create as many 'alternate' distributions as you have simulation time or 
patience for.
 
This pre-characterised noise can be introduced into the SPICE model in a number 
of ways.
a) For example, the distribution can be used to control a variable length delay 
line, through which your signals propagate., or a VCO as mentioned previously.
b) Alternately, a little 'intentional' power supply noise injected on the final 
drive stage, can with care create a nice amount of jitter. Obviously, what you 
inject needs to be random(ish).
 
c) If simulation times a big problem, then break the simulation in half, saving 
your reference signal and pre-jitter output to disk. Then you can add any 
amount of noise/jitter/group delay using processing software such as MATLAB, or 
just C code. Suitably mangled signals can then be input as stimulus into the 
second half of the simulation. Just make sure that the saved signals are saved 
at high enough sampling rate (w.r.t. delmin) to be comparable.
 
The final method is generally how channel models are utilised in the world of 
radio propagation.
 
Of course, a tool such as StatEye can be used to model a channel as in c. It 
should be remembered that not all the features have to be used though. So, if 
modelling changes in the receiver architecture, the output of StatEye can be 
used as an input stimulus to SPICE.
 
Regards
 
Andrew
________________________________

From: si-list-bounce@xxxxxxxxxxxxx on behalf of Andrew Burnside
Sent: Tue 23/08/2005 23:07
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Accounting random jitter



Please take my earlier email with a pinch of salt.
I really should know not to post at the end of the day when I am tired!
Whilst, I think that much of what I said is true, there is no point in 
reinventing the wheel, when there is a good tool such as Stateye available. I 
just wish that it had been around a few years ago!

Andrew
________________________________

From: si-list-bounce@xxxxxxxxxxxxx on behalf of Scott McMorrow
Sent: Tue 23/08/2005 20:56
To: Pratt, Gary
Cc: ray.anderson@xxxxxxxxxx; james.plesa@xxxxxxx; edpc108@xxxxxxxxx; 
si-list@xxxxxxxxxxxxx; ransom@xxxxxxxxxxxxx; al@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Accounting random jitter






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