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First of all, I understand there are similar posts, however, they are to do with previous generation iPhones. This is specifically about the iPhone X.

How accurate is the GPS information that developers can get when using the iPhone X?

I am thinking about making a Raspberry Pi project where I need to get precise location data to create a map and calculate speed for some telemetry system I am making.

To check that it is do able first, I will test it with my iPhone X as I already have all the hardware. If the GPS is not accurate enough, I will go straight to the Pi setup. For example the GPS module I will be using updates location 10 times a second. What does the iPhone X do?

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How accurate is the GPS information that developers can get when using the iPhone X?

It's a subjective question and the perceived accuracy of location data may differ based on usage, location and signal availability. While the real answer can only be obtained by actually capturing the data, I'll try to share some information which can help you with your query.

iPhone X along with its contemporaries iPhone 8 and iPhone 8 Plus, are the first iPhones to include support for not one but four geolocation services:

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A brief description of each one of them:

  1. GPS: Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Air Force.

  2. GLONASS: Globalnaya navigatsionnaya sputnikovaya sistema, or Global Navigation Satellite System, is a space-based satellite navigation system operating in the radionavigation-satellite service. It provides an alternative to GPS and is the second navigational system in operation with global coverage and of comparable precision.

  3. Galileo: Galileo is the global navigation satellite system (GNSS) that is being created by the European Union (EU) through the European GNSS Agency (GSA). One of the aims of Galileo is to provide an independent high-precision positioning system so European nations do not have to rely on the Russian GLONASS, Chinese BeiDou or US GPS systems, which could be disabled or degraded by their operators at any time. The use of basic (lower-precision) Galileo services will be free and open to everyone. The higher-precision capabilities will be available for paying commercial users. Galileo is intended to provide horizontal and vertical position measurements within 1-metre precision, and better positioning services at higher latitudes than other positioning systems.

  4. QZSS: The Quasi-Zenith Satellite System (QZSS) is a project of the Japanese government for the development of a four-satellite regional time transfer system and a satellite-based augmentation system for the United States operated Global Positioning System (GPS) to be receivable in the Asia-Oceania regions, with a focus on Japan. The goal of QZSS is to provide highly precise and stable positioning services in the Asia-Oceania region, compatible with GPS.

While GPS support has been available since iPhone 3G, GLONASS was added starting with iPhone 4S (ref: List of iOS devices).

Some references from the Web which back the claim that availability of multiple service support will lead to more accurate positioning data:

According to the European Global Navigation Satellite Systems Agency, Galileo support in the new iPhones will allow users to benefit from more precise positioning that's able to combine GPS, GLONASS, and Galileo signals. Galileo, says the agency, has a modern signal structure that's able to help users better maintain their position fix when navigating through cities worldwide.

Multi-satellite support also increases signal availability in urban areas where buildings can obstruct the sky and limit the number of visible satellites. Galileo has 15 operational satellites in orbit and three that are in testing, compared to 31 GPS satellites and 24 GLONASS satellites. By 2020, Galileo is expected to have 30 satellites operational.

Among the new features of the latest Apple offerings is the fact that the newest versions of the iPhone are Galileo-enabled. The resulting ‘multi-constellation’ capability means that users of the new iPhones will be able to benefit from more precise positioning that combines GPS, Glonass and Galileo signals. The use of multi-constellation increases signal availability, especially in urban environments, where buildings obstruct the sky and limit the number of satellites visible. In terms of accuracy, Galileo’s modern signal structure has better resistance to multipath, which helps users maintain their position fix when navigating in cities.

Combining GPS, GLONASS and Galileo signals lets new iPhones increase signal availability in urban environments where buildings obstruct the sky and limit the number of satellites visible.

In terms of accuracy, Galileo’s signal structure is said to provide better resistance to multipath, which helps iPhone users maintain their position fix when navigating in cities.

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iPhone X GPS accuracy is the same as iPhone 8, 7, 6S, 6, 5S and all recent galaxy phones. That is because none of the smartphones come with a GPS chip in them.

Phones do not have GPS, they have GPS capability. This capability stems from the modem chip that’s used to make phone calls and stems as a byproduct designed to receive GPS signals originally intended for clock maintenance needed for high speed internet to maintain internal phone clock.

They quickly realized it can also be used as low quality GPS, this is why current phones have such horrible accuracy of a radius that’s about 15 meters (45 feet) in diameter in some less optimal conditions, where real GPS with a GPS chip, update rate of 10 times per second, and SBAS, you will get below 1 meter precision without breaking sweat.

Phone GPS capability is okay for walking around a city, due to having more GNSS ability makes it very good for getting signal in places with tall buildings, but having Glonass, Compass etc in addition to GPS itself, does not increase accuracy, a dedicated GPS chip would be the only thing Apple could add, those chips are insanely small and insanely good at what they do, there’s plenty of space inside the iPhone, like for example that piece of plastic where headphone jack used to be.

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    I think you can add an answer and make your point without insulting another user. Please see the site Code of Conduct and edit your answer to remove the part about the other answer. – fsb Sep 6 '18 at 13:10
  • Do you have an article or something you could link to provide more backstory of your point? To a casual observer, for a company to claim they have GPS in their phone but not actually put GPS in it would seem like false advertising and makes it seem like there is more to the story. Also in my subjective experience, it seems like my phone can locate me precisely, even in the wilderness - would that be possible if the phone did not have a dedicated GPS chip? – bassplayer7 Sep 12 '18 at 20:21
  • @bassplayer7 I mean you can spend a few hours googling to drive the point home, browse Qualcomm website you’ll see there’s no dedicated GPS chip anywhere. I didn’t say it doesn’t work, it’s just doesn’t work nearly as well as it could if it had the chip. – Jack Shephard Sep 12 '18 at 20:26
  • Thanks for explaining. I think that's part of the reason I'm having trouble understanding your answer, though: some brief Google searching seems to make it clear that all iPhones since the iPhone 3GS have GPS chips in them. Things like this: lifewire.com/iphone-gps-set-up-1683393 – bassplayer7 Sep 12 '18 at 20:33
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    @lxgr I have learned much more since making my post, I have experimented with my iPhone 8 and a real Garmin GPS with SBAS, and my old iPhone 5S. Indeed there is a difference and I made a Reddit post on it. iPhone 5S performs close to the GPS, iPhone 8 and above use some HORRIBLE prediction algorithms of location data as opposed to showing raw data, it looks horrible and not precise, instead of giving iPhone 2-5Hz GPS and SBAS support or maybe even dual channel differential — Apple decides that software smoothing is what is needed. – Jack Shephard May 28 at 13:24

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