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GPS satellite

Smartphones released in 2018 could find location to within centimetres

A new satellite positioning chip, the BCM47755, will be the world’s first dual-frequency global navigation satellite service (GPSS) receiver designed for the mass market, and will have minimal power consumption.

The chip could offer positioning to an accuracy of 30cm, a significant improvement on today’s typical accuracy of approximately five metres.

Satellite services such as the US’s GPS, Europe’s Galileo or Russia’s GLONASS allows devices to identify their longitude, latitude and altitude by measuring their precise distances from at least three satellites.

Most positioning satellites broadcast a radio signal which contains information about its location, the time the signal is sent, and a “signature” unique to the satellite: these are broadcast using the L1 radio frequency, intended for civilian use. By measuring the time taken to receive these time-marked signals from the satellites, a smartphone, wearable or other device can identify its location.

A small but growing number of satellites also broadcast L5 signals, which are not currently in commercial use. These complex signals come in briefer bursts, rendering them less vulnerable to becoming distorted by reflections from buildings and trees than L1 frequency signals. As just the first L5 signal and not subsequent reflections are processed, L5 provides a much “sharper” signal.

The new chip uses this new generation of L5 signals in addition to L1 signals to provide a far more precise positioning service which could be accurate to within 30cm.

Broadcom, the chip’s manufacturer, has adapted the chip manufacturing process, installed “new radio architecture” and added a power-saving dual-core sensor hub to reduce its power consumption to half that of the chips in use today.

The company unveiled the GNSS receiver at the ION GNSS+ conference in Portland, Oregon, that it is sampling a chip capable of giving a magnitude higher precision. This is, according to Broadcom, the first such chip.

According to Broadcom, the BCM47755 has been included in the design of some new smartphone models due for 2018 release, although Broadcom has not specified which models.

In August, Mitsubishi, Bosch and other companies established Sapcorda Services GmbH, aiming to deliver satellite positioning services to the automotive, industrial and consumer markets with centimetre-scale accuracy. This would use ground stations to determine errors due to distortion from satellite signals, which can be communicated to smartphones and other devices.

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