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Are barometric sensors commonplace in smartphones?

by godelmachine 8y ago

dingo_bat 8y ago
Almost all android flagships have a barometer.
zik 8y ago
Most flagship phones have them.
greglindahl 8y ago
Yes, and they're needed because GPS is much less accurate in the vertical direction. Even the fitbit in my pocket has a barometric sensor, to be able to count stairs.
- askvictor 8y ago
  GPS _is_ less accurate vertically in certain circumstances (namely when you only have a lock on 3 satellites, as there are two possible altitudes you could be at), but usually this doesn't matter unless you're flying - otherwise just figure you're on the Earth's surface, and cross-reference map data for the altitude. Inside multi-storey buildings it's a different story, but you won't be getting a GPS signal indoors anyway.
  - michaelt 8y ago
    GPS _is_ less accurate vertically in certain circumstances GPS is less vertically accurate all the time, due to 'dilution of precision', which depends on the position of satellites in the sky [1]. When you move x distance horizontally, unless you have a very poor view of the sky some satellites will get closer and others further away. When you move the same distance vertically, all satellites will get closer but by differing amounts [2]. As vertical moves produce a smaller change in the measured data, noise in the measured data has greater impact on the vertical measurement. just figure you're on the Earth's surface, and cross-reference map data for the altitude Once GPS data reaches an app on a phone, they're free to discard the height data, true. But the GPS reception module itself doesn't contain a detailed elevation map of the earth; there isn't enough memory to store a detailed map, or any way to push out map updates. usually this doesn't matter unless you're flying The main application I've seen for height data is sports trackers. For example, cycling and running up steep hills is hard work compared to running the same distance on the flat. Some trackers will even set challenges like climbing 2000m in a month [3]. Things like drone altitude control also like having height data, obviously. [1] http://www2.unb.ca/gge/Resources/gpsworld.may99.pdf http://www2.unb.ca/gge/Resources/gpsworld.may99.pdf [2] Because you can only see satellites above you, never below. Unless you're high enough that the planet stops getting in the way. [3] https://www.strava.com/challenges https://www.strava.com/challenges
doomlaser 8y ago
That's the component that Apple replaced the headphone jack with, apparently.
- godelmachine 8y ago
  That's interesting! Do you know where I can find more information about this?
- askvictor 8y ago
  iPhones have had barometers since the 6: https://en.wikipedia.org/wiki/IPhone#Barometer https://en.wikipedia.org/wiki/IPhone#Barometer
  - doomlaser 8y ago
    And they put an extra big one in the space formerly occupied by the headphone jack: https://www.theverge.com/2016/9/16/12941040/iphone-7-teardown-plastic-behind-where-headphone-jack-used-to-be https://www.theverge.com/2016/9/16/12941040/iphone-7-teardow...

Are barometric sensors commonplace in smartphones?

dingo_bat 8y ago

Almost all android flagships have a barometer.

zik 8y ago

Most flagship phones have them.

greglindahl 8y ago

Yes, and they're needed because GPS is much less accurate in the vertical direction. Even the fitbit in my pocket has a barometric sensor, to be able to count stairs.

askvictor 8y ago
GPS _is_ less accurate vertically in certain circumstances (namely when you only have a lock on 3 satellites, as there are two possible altitudes you could be at), but usually this doesn't matter unless you're flying - otherwise just figure you're on the Earth's surface, and cross-reference map data for the altitude. Inside multi-storey buildings it's a different story, but you won't be getting a GPS signal indoors anyway.
- michaelt 8y ago
  GPS _is_ less accurate vertically in certain circumstances GPS is less vertically accurate all the time, due to 'dilution of precision', which depends on the position of satellites in the sky [1]. When you move x distance horizontally, unless you have a very poor view of the sky some satellites will get closer and others further away. When you move the same distance vertically, all satellites will get closer but by differing amounts [2]. As vertical moves produce a smaller change in the measured data, noise in the measured data has greater impact on the vertical measurement. just figure you're on the Earth's surface, and cross-reference map data for the altitude Once GPS data reaches an app on a phone, they're free to discard the height data, true. But the GPS reception module itself doesn't contain a detailed elevation map of the earth; there isn't enough memory to store a detailed map, or any way to push out map updates. usually this doesn't matter unless you're flying The main application I've seen for height data is sports trackers. For example, cycling and running up steep hills is hard work compared to running the same distance on the flat. Some trackers will even set challenges like climbing 2000m in a month [3]. Things like drone altitude control also like having height data, obviously. [1] http://www2.unb.ca/gge/Resources/gpsworld.may99.pdf http://www2.unb.ca/gge/Resources/gpsworld.may99.pdf [2] Because you can only see satellites above you, never below. Unless you're high enough that the planet stops getting in the way. [3] https://www.strava.com/challenges https://www.strava.com/challenges

doomlaser 8y ago

That's the component that Apple replaced the headphone jack with, apparently.

godelmachine 8y ago
That's interesting! Do you know where I can find more information about this?
askvictor 8y ago
iPhones have had barometers since the 6: https://en.wikipedia.org/wiki/IPhone#Barometer https://en.wikipedia.org/wiki/IPhone#Barometer
- doomlaser 8y ago
  And they put an extra big one in the space formerly occupied by the headphone jack: https://www.theverge.com/2016/9/16/12941040/iphone-7-teardown-plastic-behind-where-headphone-jack-used-to-be https://www.theverge.com/2016/9/16/12941040/iphone-7-teardow...