Superaccurate GPS Chips Coming to Smartphones in 2018

[ IEEE Spectrum Post ]

Broadcom has released the first mass-market GPS chips that use newer satellite signals to boost accuracy to 30 centimeters

Your GPS isn’t accurate enough for your navigation app to tell if you’re on the highway or on the road beside it.

Those days are nearly at an end. At the ION GNSS+ conference in Portland, Ore., today Broadcom announced that it is sampling the first mass-market chip that can take advantage of a new breed of global navigation satellite signals and will give the next generation of smartphones 30-centimeter accuracy instead of today’s 5 meters. Even better, the chip works in a city’s concrete canyons, and it consumes half the power of today’s generation of chips. The chip, the BCM47755, has been included in the design of some smartphones slated for release in 2018, but Broadcom would not reveal which.

GPS and other global navigation satellite systems (GNSSs), such as Europe’s Galileo, Japan’s QZSS, and Russia’s Glonass, allow a receiver to determine its position by calculating its distance from three or more satellites. All GNSS satellites—even the oldest generation still in use—broadcast a message called the L1 signal, which includes the satellite’s location, the time, and an identifying signature pattern. A newer generation broadcasts a more complex signal called L5 at a different frequency in addition to the legacy L1 signal. The receiver essentially uses these signals to fix its distance from each satellite based on how long it takes the signal to go from satellite to receiver.

Broadcom’s receiver first locks onto the satellite with the L1 signal and then refines its calculated position with L5. The latter is superior, especially in cities, because it is much less prone to distortions from multipath reflections than L1.

The BCM4775 is just the latest development in a global push for centimeter-level navigation accuracy. Bosch, Geo++, Mitsubishi Electric, and U-blox established a joint venture called Sapcorda Services in August, to provide centimeter-level accuracy. Sapcorda seems to depend on using 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.