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more accurate Sony GNSS/GPS Chip for Garmin sports wearables

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Image | Sony

new Sony GNSS Chipset

Thank you @Mario

Interesting times ahead for sports-based GNSS accuracy.

Not only is there a brand new Sony GNSS chipset from Aug 2020 that claims to be more accurate, but there are also iterated versions of the older one that might explain changes we’ve seen in GNSS accuracy over the last two years as well as which provide inbuilt support for UDR (like Suunto’s FusedTrack). Indeed I’ve had it confirmed directly from a manufacturer that different models of sports watches do use different versions of these chips and that may well explain SOME of the variations in performance we’ve seen from the Sony chips across all the brands.

I will update THIS post if more detailed info comes to light from suppliers who I’ve asked to comment but it’s unlikely they will meaningfully comment.

Background

The Sony GNSS chip is widely used in sports wearables, although not in Wear OS and probably not in Apple Watch. The reasons it’s used are primarily twofold 1) it uses tiny amounts of power, 6mW, which lets the battery work for longer and 2) It supports multiple constellations like GPS+Galileo which at least give the marketing illusion of greater accuracy if nothing else.

I had assumed that the original Sony CXD5603GF chip was the one in universal, widespread usage. It might be…but I’m guessing it’s been silently superseded. Here’s the list of existing Sony models which, for our purposes, have superficially similar performance (specs, here)

I think almost all of us had been assuming that there were algorithm changes that fixed various performance issues and, whilst that might be partly true, I suspect the better-selling sports wearables have been silently changing the chipsets too and those chipsets simply might have better performance characteristics inherent in the hardware…or not. So, IIRC, the first Garmin to use the Sony chipset was the Forerunner 945 and I would bet that the Forerunner 745 announced this week uses a different, later one.

You will note that some models use UDR which incorporates motion sensor feedback into the positioning calculations and the keener ones amongst you will wonder why SBAS is not mentioned in the specs of any of these older models and yet Polar claims to use it (SBAS – positional data from fixed ground stations)

The Future of GNSS in Sports Wearables 2021

What Sony has just released is a GNSS sports Wearable chipset that works with dual-frequency bands. This does NOT MEAN GPS plus GALILEO nor GPS plus GLONASS. Each of the GPS, Galileo and BeiDou constellations operate over two frequency bands and when the new band frequency (and/or both bands together?) are used then greater accuracy can be obtained.

The bands have ‘L’ numbers and my reading of the Sony specs is that the new Sony chipset only works with L1 and L5 bands which effectively means GPS. Galileo and GLONASS do have multiple bands but I don’t know for sure if they can be commercially used and/or if the L1/L5 frequencies can be worked with – initially I’m assuming not.

So one possible future for us in 2021 is that Glonass and Galileo will be temporarily ditched in favour of multi-band GPS (L1 and L5). Of course, it’s never that simple.

Here is a selection from specs of the new Sony chipsets

Power Consumption  

1.5 GHz/1.2 GHz simultaneous reception

CXD5610GF

9mW

CXD5610GG

11mW

1.5GHz reception 6mW 7mW
1.2GHz reception 7mW 8mW

 

I’ve highlighted in bold the 6mW power consumption as this is the same as the current Sony chips require. As you can see to increase accuracy requires 50% more power (to 9mW).

But don’t forget that the current scenario of GPS+GLONASS or GPS+GALILEO also requires more power than GPS-only reception, from experience let’s say 20% more power.

Multi-band chipsets are not a new revelation, I’ve talked here about multi-band reception on a few occasions but that tech has really only been used in some smartphones.

Take Out

These chips are going to be used (I have had that effectively confirmed). There will probably be a software switch to enable/disable the greater accuracy mode.

Whether or not the new chip will materially increase accuracy remains to be seen but I would be hopeful of some limited improvements. Remember that using multiple constellations like GPS+GALILEO merely increases the likelihood of the base level of accuracy being achieved…we are talking now of increasing accuracy NOT making inaccuracy more consistent.

Will multiple constellations (GPS+Galileo) work together in some combination with multiple bands (L1+L5)? Yes (See comments below, maybe not on the Sony)

The current crop of sports wearables from Garmin, Polar and Suunto have more than adequate battery lives for most usages. Being able to sacrifice some battery life for greater performance will CERTAINLY appeal to some athletes – me, for a start ;-).

Spanner in the works?

There ARE still more & DIFFERENT improvements in GNSS accuracy that can happen in the relatively near future, perhaps even a step change over and above what Sony might enable here.

Sorry, that was a relatively hard-going piece. If you want to read something more entertaining with a GPS theme, then try this

Joshua Cheptegei | Gutted About his STRAVA GPS Track | 5000m World Record

 

 

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