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The WiFiMon test server includes configured templates from NetTest, Boomerang and SpeedTests (HTML5), which provide information about RTTs and ping (ICMP) network relevant data like bandwidth and latency (represented in Figure 2B as lines marked as 2.1, 2.2, and 2.5). A standard image size is downloaded for NetTest, and for Boomerang it can be customisable to a maximum of 5 MByte size. The location of the WTS and its topological distance from the monitored WiFi network has a major impact on the crowdsourced measurement accuracy and reliability. You can read more about this here.
WiFiMon Software Probe (WSP)
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