Energy measurement

The measurement equipment consists of a Windows PC, a hardware data acquisition card, and a wire connector box. The PC is installed with National Instrument's data acquisition software called $Labview$. The voltage is measured across a sense resistor connected in series with the battery to obtain the system power consumption. It is sampled at a rate of $400Hz$. $Labview$ is programmed to integrate power every second. By carefully designing the benchmarks, the energy consumption of software events of interest can be captured. The energy measurements for a given benchmark were made on the handheld computers on the same day without interruption (in order to minimize the day-to-day difference due to changes in temperature, slight changes in the resistance of the sense resistor, $etc.$).