Measurement Capabilities¶

Modems¶

The Newtec EL470 versions that Telecom Bretagne owns have no protocol testing capabilities. However, when in ACM mode, the ACM controller (the HUB) keeps a log file containing the modulation and coding schemes as well as bitrate and Es/N0 estimates . This is information is stored in a .csv file containing the following:

Timestamp,Demod,RqModCod,EsNo,CarrierBitrate
2014-12-12 15:05:19,1,16APSK-2/3,11.20,1445835
2014-12-12 15:05:24,1,16APSK-2/3,10.72,1324072
2014-12-12 15:05:28,1,16APSK-2/3,10.61,1324072
2014-12-12 15:05:31,1,16APSK-2/3,10.66,1324072
2014-12-12 15:05:34,1,8PSK-3/4,10.19,1313479
2014-12-12 15:05:37,1,8PSK-3/4,11.87,1313479
2014-12-12 15:05:41,1,8PSK-3/4,10.40,1313479
2014-12-12 15:06:47,1,QPSK-5/6,6.93,884389
2014-12-12 15:06:51,1,QPSK-5/6,8.18,884389
2014-12-12 15:06:56,1,QPSK-5/6,7.02,825503

It is unclear though what the logging frequency is. We have determined that this rate depends on the rate at which Es/N0 estimates change. From the csv file we can extract the following information:

• Timestamp (in seconds)
• Modcod parameter (modulation + coding rate)
• Estimate of E _s / N ₀
• Information bitrate (in bps)

Traffic generation and capture¶

In order to measure performance at the application level we will use Iperf. Iperf is a tool to generate streams of TCP and UDP traffic as well as measuring throughput and other statistics. In order to have a finer control over throughput reporting, we will capture all traffic and perform an offline calculation of throughput using #pcaptput.