High end smartphones later in 2018 should use Broadcom chip enables centimeter accurate GPS

GPS World tested a development kit systems with the Broadcom® BCM47755 chip. The chip can use the regular L1 GPS frequency as well as the more accurate L5 GPS frequency.

The recently released Samsung Galaxy S9 did not have the BCM47755 chip. It is possible that the Samsung Galaxy Note 9 which will be released in the Q3 2018 could have it and the Google Pixel 3 in Q4 2018 or the new Apple iPhone.

Tests with Broadcom BCM47755 and modified android cellphones

Horizontal accuracy for Broadcom reached 10 centimeters while the precision receiver reaches better than 3 centimeters. The degradation is in part due to the difference in quality of the carrier phase and the different number of dual frequency satellites processed. Precision devices provide measurements on E1/L1, L2 and L5/E5 providing at least dual frequency data from GPS, GLONASS, Galileo, BeiDou and QZSS.

The Broadcom chipset tested provided dual frequency GPS and Galileo along with single-frequency GLONASS and BeiDou; however, due to limited BeiDou constellation visible in California, data from this constellation was not used.

The RTX-Fast solution for Broadcom reaches 30 cm horizontal error in 68% of the cases in approximately 12 minutes. The RTX-Fast convergence using precision GNSS data is near instantaneous.

Similar tests were performed using an external cell-phone GNSS antenna, which is close to the antenna used in a typical smartphone. RTK performance shows centimeter-level accuracies and reasonable convergence times, which are slightly worse than the results with the professional antenna.

Based on the testing with existing devices (modified Nexus 9 and Samsung S7) it is possible to achieve position solutions of 1–2-meter accuracy in ideal static scenarios. This is a significant improvement in accuracy for Android based devices.

Increasing numbers of GPS satellites provide the L5 frequency.

Japan’s US $1.9 billion Quasi-Zenith Satellite System (QZSS) uses error correction and improves on urban navigation by adding a set of satellites that guarantees one is visible directly overhead even in the densest part of Tokyo. The system is to come online in 2018.

Bosch, Geo++, Mitsubishi Electric, and U-blox established a joint venture called Sapcorda Services in August, 2017 to provide centimeter-level accuracy. Sapcorda uses ground stations to measure errors in GPS and Galileo satellite signals due to atmospheric distortions. Those measurements would then be sent to receivers in handsets and other systems to improve accuracy.

The Broadcom® BCM47755 location hub is a single-chip device that combines location awareness capabilities with the typical functions of a sensor hub. The combination provides synergistic benefits that cannot be achieved with multiple ICs, such as low power consumption, higher accuracy, reduced footprint and a smaller BOM.

The BCM47755 supports two GPS frequencies (L1+L5), and as a result, achieves lane-level accuracy outdoors and much higher resistance to multipath and reflected signals in urban scenarios, as well as higher interference and jamming immunity.

Furthermore, the BCM47755 incorporates numerous technologies that enable ultralow power consumption in both the location function and the sensor hub function. The device features a low-power RF path, a Big/Little CPU configuration composed of an ARM-based 32-bit Cortex-M4F (CM4), an ARM-based Cortex-M0 (CM0), and is built in a 28 nm process.

The BCM47755 chip supports two frequencies (L1+L5), and as a result, achieves lane-level accuracy outdoors and much higher resistance to multipath and reflected signals in urban scenarios, as well as higher immunity to interference and jamming. The BCM47755 can simultaneously receive the following signals:
• GPS L1 C/A
• BeiDou (BDS) B1
• Galileo (GAL) E1
• GPS L5
• Galileo E5a

It can be used in
• Smartphones
• Tablets
• Mobile accessories
• Wearables
• Digital cameras


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