Methods for searching for satellite signals and global navigation satellite system receiver

Abstract

Methods and apparatuses for searching for satellite signals are provided. One of the proposed methods of searching for satellite signals includes: searching for satellite signals according to measurement predictions; searching for satellite signals of a reference satellite without referring to the measurement predictions; determining if measurements derived from the reference satellite are consistent with the measurement predictions; and searching for satellite signals of other satellites without referring to the measurement predictions if the measurements derived from the reference satelliteare determined to be inconsistent with the measurement predictions. If the measurements derived from the reference satellite are determined to be inconsistent with the measurement predictions, navigation information for use in the generation of the measurement predictions is determined to be stale. The methods and apparatuses provided by the invention support various searching modes, effectively shorten the first positioning time and improve speed and accuracy for searching satellite signals.

Description

Technical field [0001] The invention relates to a Global Navigation Satellite System (GNSS), in particular to a method and related devices for searching satellite signals. Background technique [0002] The current Global Navigation Satellite System (GNSS), such as the Global Position System (GPS) in the United States, Galileo in the European Union, or the GLObal NAvigation Satellite System in Russia (GLObal NAvigation Satellite System) , GLONASS), etc., are widely used in many applications. The global navigation satellite system receiver can use to receive and analyze the coded signals transmitted from multiple satellites orbiting the earth to determine its coordinate position, and the global navigation satellite system receiver can determine its initial position from the beginning of searching for satellite signals. The time spent is called Time To First Fix (TTFF), and when evaluating the performance of a global navigation satellite system receiver, the time to first fix is ​​...

AI Technical Summary

Problems solved by technology

[0004] Unfortunately, if the GNSS receiver is in an unfavorable RF environment, there is a high chance that the GNSS receiver will not be able to achieve a time to first fix (i.e. will not be able to complete a fix)

It is well known that GNSS receivers may not be able to locate inside buildings, in basements, and on urban streets with tall buildings on both sides, because these places are some environments that block radio frequency

In addition, if the navigation information stored in the non-volatile memory unit does not correspond to the actual operating conditions of the GNSS receiver, the GNSS receiver will also fail to achieve a time to first fix

For example, when the previously obtained position stored in the non-volatile memory unit is in the southern hemisphere, but the GNSS receiver is actually in the northern hemisphere, this inconsistency can cause GNSS system receivers produce some incorrect measurement forecasts, and cause the GNSS receivers to continue searching for satellites below the horizon based on these incorrect measurement forecasts, therefore, in these cases, GNSS The receiver will not be able to complete the positioning work

[0005] If the GNSS receiver is unable to achieve a time to first fix due to incorrect measurement predictions, these incorrect measurement predictions should be discarded, but if the GNSS receiver is due to poor radio frequency environment and time-to-first-fix cannot be achieved, these measurement forecasts should not be discarded

However, it is difficult to identify the good and bad RF environment and the reason why the GNSS receiver cannot achieve the time of first fix in the current relevant technology

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