I was trying a verilog-A model to calculate jitter and phase noise.  I have following issue regarding the measurement of long term jitter.  How exactly can i calculate the same. In my present verilog-A model for the VCO I am dumping the $realtime. To calculate the N-period long term jitter I am using following matlab commands

Code:

for I=1:1:100000,
    x(I)=time_long(I+nperiod)-time_long(I);
end
std(x) 

(here nperiod is period for which I need to calculate the jitter and time_long is simulation dump file.)

Now my question is: since the division ratio in my design is 10, do  I need to divide this standard deviation by sqrt(ratio) as I would do if I were calculating the period jitter (I feel that I do not need to)?  Can anyone suggest a better method to measure the long term jitter?
Regards
Amit