Jitter formula used
- To: iperf-users --at-- dast.nlanr.net
- Subject: Jitter formula used
- From: "Tiago Junqueira" <tiago.junkeira --at-- gmail.com>
- Date: Thu, 14 Jun 2007 18:09:58 +0200
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Hi,
I would like to know which average Jitter's formula iperf uses,
because I need to compare the real results with results from a
simulator.
In the simulator i have access to the packet sent and received time,
and i'm applying the formula:
for (i=1;i<=last_packet;i++) {
jitter=(((packet_receive_time_array[i])-(packet_send_time_array[i]))-((packet_receive_time_array[j])-(packet_send_time_array[j])))/(i-j);
Jsum=jitter+Jsum;
}
average_jitter=Jsum/(num_packets-1)
But in RFC 1889 for the instantaneous jitter is used:
D(j,i)=(Rj-Sj)-(Ri-Si)
Then the instantaneous jitter is:J=J+(|D(i-1,i)|-J)/16
And how to calculate the average?
Jsum=J+Jsum with a for cycle, and do the same:
average_jitter=Jsum/(num_packets-1)??
Thanks in advance, Tiago Junqueira