DescriptionEnergy efficient localization is important for lots of smartphone applications. The research community has argued that fixed duty cycling of GPS is not a good choice for trajectory-based services concerning route accuracy. In this note, we show that duty cycling of a smartphone GPS receiver achieves considerable energy efficiency without sacrificing much route accuracy. When increasing sampling period to 120 seconds, it saves at least 78% energy in comparison to continuous GPS sampling, while the loss of route accuracy tends to be stable at 0.23 to 0.25.