Case Study: Measuring the Incremental Battery Draw of Advanced Audio Processing

Mobile phones are rapidly and dramatically expanding beyond their historical usage as voice-only communications devices, adding a variety of wireless data-fed text, email, web browsing and other functions, supplementing (and in many cases supplanting) the facilities of dedicated still and video cameras, and serving as portable multimedia playback platforms. But all of these functions consume power, and both users and designers of mobile phones are very concerned about battery life. Similarly, watching the latest Hollywood blockbuster on a tablet computer dramatically dims in appeal if you can't get through the movie without depleting the battery. And battery life is equally important for dedicated-function portable audio and video playback devices.

In all of these devices, there’s a tension between, on the one hand, the desire for additional features and higher quality audio and video, and, on the other hand, the desire to maximize between-charge usage. Recently, an audio algorithm supplier contracted with BDTI to determine the incremental power and energy draw, therefore battery life impact, of audio add-on software functions running on a commercially available tablet. BDTI designed a detailed experimental approach to obtain accurate power results. This included selecting appropriate test equipment and designing a dedicated circuit to enable accurately measuring voltage and current at the tablet’s battery terminals. BDTI also devised tests to validate the accuracy of the measurements. BDTI then measured the incremental power consumption attributed to the added audio algorithms in various uses cases, such as when playing a movie, and when playing audio content alone (with the display off). And once the results were measured, BDTI performed statistical and error analysis to ensure that the results were statistically significant, and to quantify the margin of error for each measurement.

The algorithm supplier found the results of the study very useful, not only in assessing the battery life impact of its software on this particular tablet, but also in being able to roughly extrapolate these results to other tablets, smartphones, portable multimedia players and other devices with similar application processor foundations but differing display sizes and other characteristics, as well as divergent battery capacities. If you'd like to leverage BDTI's unique understanding of both application processors and the code that runs on them, as well as our abilities to use this understanding to perform reliable power consumption analysis, contact Jeremy Giddings at +1 (925) 954-1411 or giddings@BDTI.com.