Jitter and intrapacket delay

[Carter Bullard]

Hey Urtho,
I know it's a minor point, and not to be too noisy on the list, but  
it is
important to be right on the math!!

std deviation is the square root of the variance, so .....

    std dev = variance ^ 0.5;

so

    variance = std deviation ^ 2.0;

I'm pretty confident about this, and if you want to bet, I will
take my winnings in dollars or euros!   :o)

Glad to see that argus is helping!!

Carter


On Jul 17, 2007, at 3:38 PM, Urtho wrote:

>
> On 2007-07-17, at 21:23, Carter Bullard wrote:
>
>> Hey Urtho,
>> remember std deviation is the square root of the variance, so
>>        variance = stddev ^ 2.0.
>
> :)
>  Your words put into an equation:
>      stddev = variance ^2.0
>
> and thus variance = stddev^0.5
>
>>
>> well, 50 pps is a packet interval of 20mSec which is pretty normal  
>> for
>> some VoIP implementations.  do you think 50 is too high, or too low?
>>
> 50pps is what I set in my devices but I meant that some flow have  
> higher rate than 50pps and I should check how is that possible.
> eg with "statistical" analysis of the same data in Ethereal.
>
>> also remember that argus is good at dealing with silence suppression
>> for some rtp based codecs, so the jitter may reflect a higher packet
>> rate than what is actually seen for the general flow when silence
>> suppression is in use.
>>
> Yes, I've just diagnosed that some of my installations have VAD  
> turned on by mistake thanks to Argus :))
>
> Urtho.
>