I urgently need help to my master degree thesis and I will be grateful for any hint.

I ran iperf in udp mode using this commands:

Code:
# iperf -s -u -f k -i 1 
# iperf -c 192.168.0.105 -u -b 68.8k -l 172 -t 60 -f k -i 1 -P 10 -F g711-glos.wav
-P parameter is different for each subsequent analysis

Example of results from server side:

Code:
[  3] local 192.168.0.105 port 5001 connected with 192.168.0.100 port 36324
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3]  0.0- 1.0 sec  8.40 KBytes  68.8 Kbits/sec  0.783 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3]  1.0- 2.0 sec  8.40 KBytes  68.8 Kbits/sec  0.367 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3]  2.0- 3.0 sec  8.23 KBytes  67.4 Kbits/sec  0.140 ms    0/   49 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3]  3.0- 4.0 sec  8.57 KBytes  70.2 Kbits/sec  0.181 ms    0/   51 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3]  4.0- 5.0 sec  8.40 KBytes  68.8 Kbits/sec  0.240 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3]  5.0- 6.0 sec  8.40 KBytes  68.8 Kbits/sec  0.158 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3]  6.0- 7.0 sec  8.06 KBytes  66.0 Kbits/sec  0.232 ms    2/   50 (4%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3]  7.0- 8.0 sec  8.40 KBytes  68.8 Kbits/sec  0.433 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3]  8.0- 9.0 sec  8.40 KBytes  68.8 Kbits/sec  0.413 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3]  9.0-10.0 sec  8.40 KBytes  68.8 Kbits/sec  0.284 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 10.0-11.0 sec  8.40 KBytes  68.8 Kbits/sec  0.151 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 11.0-12.0 sec  8.40 KBytes  68.8 Kbits/sec  0.163 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 12.0-13.0 sec  8.40 KBytes  68.8 Kbits/sec  0.177 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 13.0-14.0 sec  8.40 KBytes  68.8 Kbits/sec  0.130 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 14.0-15.0 sec  8.40 KBytes  68.8 Kbits/sec  0.221 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 15.0-16.0 sec  8.40 KBytes  68.8 Kbits/sec  0.351 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 16.0-17.0 sec  8.40 KBytes  68.8 Kbits/sec  0.221 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 17.0-18.0 sec  8.40 KBytes  68.8 Kbits/sec  0.279 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 18.0-19.0 sec  8.40 KBytes  68.8 Kbits/sec  0.298 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 19.0-20.0 sec  8.40 KBytes  68.8 Kbits/sec  0.325 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 20.0-21.0 sec  8.40 KBytes  68.8 Kbits/sec  0.197 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 21.0-22.0 sec  7.73 KBytes  63.3 Kbits/sec  2.109 ms    3/   49 (6.1%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 22.0-23.0 sec  8.57 KBytes  70.2 Kbits/sec  1.175 ms    0/   51 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 23.0-24.0 sec  8.23 KBytes  67.4 Kbits/sec  1.114 ms    0/   49 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 24.0-25.0 sec  8.57 KBytes  70.2 Kbits/sec  0.634 ms    0/   51 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 25.0-26.0 sec  8.40 KBytes  68.8 Kbits/sec  0.182 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 26.0-27.0 sec  8.40 KBytes  68.8 Kbits/sec  0.137 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 27.0-28.0 sec  8.40 KBytes  68.8 Kbits/sec  0.222 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 28.0-29.0 sec  8.40 KBytes  68.8 Kbits/sec  0.549 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 29.0-30.0 sec  8.06 KBytes  66.0 Kbits/sec  0.389 ms    2/   50 (4%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 30.0-31.0 sec  8.23 KBytes  67.4 Kbits/sec  0.579 ms    1/   50 (2%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 31.0-32.0 sec  8.23 KBytes  67.4 Kbits/sec  0.936 ms    1/   50 (2%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 32.0-33.0 sec  7.73 KBytes  63.3 Kbits/sec  0.261 ms    4/   50 (8%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 33.0-34.0 sec  8.40 KBytes  68.8 Kbits/sec  0.381 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 34.0-35.0 sec  8.06 KBytes  66.0 Kbits/sec  0.512 ms    2/   50 (4%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 35.0-36.0 sec  8.40 KBytes  68.8 Kbits/sec  0.420 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 36.0-37.0 sec  7.73 KBytes  63.3 Kbits/sec  0.464 ms    4/   50 (8%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 37.0-38.0 sec  8.40 KBytes  68.8 Kbits/sec  0.310 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 38.0-39.0 sec  7.89 KBytes  64.7 Kbits/sec  0.501 ms    3/   50 (6%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 39.0-40.0 sec  8.40 KBytes  68.8 Kbits/sec  0.311 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 40.0-41.0 sec  8.40 KBytes  68.8 Kbits/sec  0.370 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 41.0-42.0 sec  8.40 KBytes  68.8 Kbits/sec  0.800 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 42.0-43.0 sec  8.40 KBytes  68.8 Kbits/sec  0.491 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 43.0-44.0 sec  8.23 KBytes  67.4 Kbits/sec  0.576 ms    1/   50 (2%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 44.0-45.0 sec  8.40 KBytes  68.8 Kbits/sec  0.365 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 45.0-46.0 sec  8.40 KBytes  68.8 Kbits/sec  0.353 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 46.0-47.0 sec  8.40 KBytes  68.8 Kbits/sec  0.654 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 47.0-48.0 sec  8.40 KBytes  68.8 Kbits/sec  1.528 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 48.0-49.0 sec  8.06 KBytes  66.0 Kbits/sec  1.596 ms    1/   49 (2%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 49.0-50.0 sec  8.57 KBytes  70.2 Kbits/sec  0.831 ms    0/   51 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 50.0-51.0 sec  8.40 KBytes  68.8 Kbits/sec  0.627 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 51.0-52.0 sec  8.40 KBytes  68.8 Kbits/sec  0.516 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 52.0-53.0 sec  8.06 KBytes  66.0 Kbits/sec  0.664 ms    2/   50 (4%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 53.0-54.0 sec  8.23 KBytes  67.4 Kbits/sec  0.492 ms    0/   49 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 54.0-55.0 sec  8.57 KBytes  70.2 Kbits/sec  0.210 ms    0/   51 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 55.0-56.0 sec  8.23 KBytes  67.4 Kbits/sec  0.233 ms    1/   50 (2%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 56.0-57.0 sec  8.40 KBytes  68.8 Kbits/sec  0.284 ms    0/   50 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 57.0-58.0 sec  8.06 KBytes  66.0 Kbits/sec  1.415 ms    2/   50 (4%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 58.0-59.0 sec  8.23 KBytes  67.4 Kbits/sec  0.188 ms    0/   49 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3] 59.0-60.0 sec  8.57 KBytes  70.2 Kbits/sec  0.197 ms    0/   51 (0%)
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3]  0.0-60.0 sec    499 KBytes  68.1 Kbits/sec  0.256 ms   29/ 3001 (0.97%)
Summary (0.0-60.0 sec) shows jitter 0.256 ms, but average from each second counted in spreadsheet shows 0.487 ms for that example. What is the reason of that? After many analysis I observed that summary jitter is always very similar to the result from last interval (59-60 sec). It looks like another survey done for short time, not the average result from 60 seconds.