Single-frequency cycle slip detection and repair based on Doppler residuals with inertial aiding for ground-based navigation systems

As effective backups for global navigation satellite systems (GNSS), ground-based navigation systems can provide positioning, navigation, and timing services in situations in which the GNSS signal is degraded or denied, such as city canyons, underground, and tunnels. To handle the issue of the poor performance of small cycle slip detection in single-frequency receivers, we propose a single-frequency cycle slip detection and repair method based on Doppler residuals with inertial aiding (DRIA). A low-cost micro-electro-mechanical system inertial measurement unit (MEMS-IMU) is employed in a tightly coupled integration to predict Doppler measurements of the receiver accurately. The Doppler residuals are used as test statistics for cycle slip detection in the DRIA method, obtained by subtracting the predictions from the observed Doppler measurements. The performance of the DRIA method is tested using a ground-based high-precision local positioning system (GH-LPS) in an indoor environment. The test results demonstrate effective cycle slip detection even for one cycle in real time using only single-frequency measurements. The DRIA method achieved a 91.2% success rate, which is an improvement of 207% compared with the method based on carrier phase residuals. During the entire kinematic experiment, the root mean square of the horizontal positioning error was 1.3 cm, which is an improvement of 97.6% over the unrepaired condition (54.0 cm) and 83.4% over the method based on the carrier phase residuals (8.0 cm). The experimental results indicate the validity of the Doppler residual methods for small cycle slip detection and repair, providing a new basis to deal with cycle slips in ground-based navigation systems.