Advantages of dual-frequency GNSS (Global Navigation Satellite System) in smartphones
A smartphone identifies its position via either satellite radio signals or GNSS (Global Navigation Satellite System). Currently, the vast majority of smartphones in the market are configured for a single-frequency GNSS, which means that the smartphone can track a single radio signal from a satellite. While single frequency GNSS is widely used, it is not resistant to multipath errors which can surface from time to time.
Multipath errors lead to a positioning inaccuracy of up to 5 meters, caused due to signals bounce off tall buildings. Often, the map of our smartphones report incorrect locations and it is unable to pinpoint the street where we are. This is because of multipath errors, which is a common cause of inaccuracy in location. Commonly the satellites use L1 band which is approximately between 1.56 to 1.58 GHz. Similar to the L1 band, there are two other major frequency bands that can be used in for GPS which are the L2 and L5 bands
Multipath errors can be nullified by using two frequencies instead of one. A dual-frequency GNSS uses two signals from two different satellites. Each signal has a different frequency. The frequencies are not fixed and vary as per the GNSS. For example, the two GPS frequencies are called L1 and L5, while Galileo frequencies are called E1 and E5a. Another advantage of dual-GPS frequency is that even if one of the frequency bands fail, the other can be used as a backup.
Single-frequency smartphones mostly use only L1/E1 frequency, while the dual-frequency ones make use of both. Using dual-frequency GNSS, position accuracy can be fine-tuned. Dual-frequency GNSS is not a technological breakthrough. In 2017 Android launched its version 8.0 Oreo which was compatible with a dual frequency GNSS. Following this, Broadcom announced the launch of BCM47755, the world’s first dual-frequency GNSS receiver for smartphone in September 2017. Dual-frequency GNSS is especially crucial for location-based services.
Using Dual-frequency GNSS boosts navigation efficiency and provides up-to-date lane information. This helps ride hailing services for enhancing and pinpointing client location. The Chinese smartphone maker Xiaomi became the first company to announce a dual-frequency enabled smartphone, with the launch of Xiaomi Mi 8 last year. Till date, Xiaomi is among the handful of mobile manufacturers that provide dual-frequency GNSS.