Abstract: Methods, systems, and apparatus for detecting poor Doppler measurements results in GNSS navigation, in one aspect, a method including: calculating a first Doppler shift value, wherein the first Doppler shift value is based on movement of a Global Navigation Satellite System (GNSS) receiver and calculated according to a Doppler measurement result; calculating a second Doppler shift value, wherein the second Doppler shift value is based on movement of the GNSS receiver and calculated according to a projection of velocity of the GNSS receiver on a line of sight (LOS) vector; comparing the first Doppler shift value with the second Doppler shift value to check an accuracy of the Doppler measurement result; and determining at least a direction of movement of the GNSS receiver in accordance with the checked accuracy of the Doppler measurement result.

Abstract: Aspects of the disclosure provide an apparatus that includes a navigation signal receiver. The navigation signal receiver includes a receiving circuit configured to receive a satellite navigation signal from a satellite and a processing circuit configured to calculate a distance between the apparatus and the satellite based on the satellite navigation signal, and determine whether the apparatus is in a detection area based on the distance, a minimum distance from the detection area to the satellite and a maximum distance from the detection area to the satellite.