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Soon 30cm GPS accuracy in sports watches and fitness wristbands?

The GPS inaccuracy of about 5 to 20 meters, which is often seen today in smartphones and sports electronics (sports watches, fitness wristbands,…), could soon be history. As Broadcom announced at this year’s Institute of Navigation GNSS+ conference in Portland, a new GPS receiver that is much more suitable for the mass market is about to be launched, at least for smartphones. This should reach a GPS accuracy of about 30cm. This is the Broadcom chip model BCM47755.

The BCM47755 will be used in some new smartphones from 2018. Broadcom does not reveal which smartphones will be honoured. These smartphones will be significantly superior to other consumer devices in terms of GPS accuracy. Confusing situations in which the navigation app, for example, thinks that it is on the road next to the motorway, even though it is already on the motorway, should no longer occur.

The BCM47755 Broadcom chip is not only much more precise, but also significantly more energy-efficient than today’s GPS receivers in smartphones, according to the manufacturer. Energy consumption should be about 50% lower. Broadcom has achieved this through three things: a more energy-efficient 28-nanometer chip manufacturing process, the introduction of a new radio architecture and the development of an energy-saving dual-core sensor hub. Sensor hubs process the raw data of the sensors in a system. In simple terms, it can be imagined as a data editor and filter that only deliver the information that is really needed to the next level.

One inevitably asks oneself why only now? What has prevented Broadcom and other chip manufacturers from delivering more accurate GPS receivers in the past? Well,”there have been too few L5 satellites in orbit so far,” says Manuel del Castillo, Broadcom’s Deputy Director of GNSS Product Marketing. Currently, about 30 of these L5-capable satellites are in orbit. This number would now be sufficient for a start, says Del Castillo. Other manufacturers such as Bosch, Geo++, Mitsubishi Electric and U-blox will probably follow suit.

L5 satellites, one must know, are newer satellites that send the so-called L5 signal and allow a more accurate positioning. Compared to the older L1 signal, L5 drastically reduces the number of signal overlaps and distortions caused by reflections, e. g. on buildings. L5 signals are therefore clearly identifiable and measurable, as they provide very clear signal peaks, even with reflections. For example, reflections in L1 often cause so-called signal blobs, which consist of the sum of several reflected signals and make it difficult to calculate an exact position.

Reflective signals always take a little longer than the direct signal between satellite and receiver and are simply ignored by the new L5 chip. The fastest signal is always taken. This is the most direct and accurate way. In the future, it will therefore be possible to make very precise track recordings and navigation in cities, since there are now always enough L5 satellites available. The BCM47755 measures L1 and L5 signals, where L5 is used only to specify the coordinates.

As fitness and sports fans, we therefore hope and speculate that L5 GPS receivers can also be used in fitness watches and wristbands. In addition to better track recording and navigation, hopefully there will be some nice side effects, such as more precise fitness metrics.

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