Tracking and Position Errors in GNSS Receivers with Intermittent Signal Tracking

Abstract

Modern global navigation satellite system (GNSS) receivers in battery-operated devices employ cyclic tracking or intermittent signal tracking to conserve power. The receivers temporarily halt signal tracking during a ‘sleep period’ and continue tracking in the remaining ‘active period.’ The ratio of active period duration to total duration within a position update interval expressed as a percentage is known as the duty cycle. Position accuracy performance equivalent to a continuously tracking receiver is desirable when operating in duty-cycled mode. However, the pseudorange accuracy and, in turn, position accuracy depend on the ability of signal tracking loops to converge faster to thermal noise during the active period. Predicting the code phase and Doppler over receiver sleep period can help this cause. This paper investigates different aspects of intermittent signal tracking in GNSS receivers, characterizes code phase and Doppler prediction errors, points out their significance in intermittent tracking, and analyzes positioning and tracking performance with various duty cycles in different user motion cases in an open sky environment. Copyright # 2016 Institute of Navigation.