This article
describes a company which uses phones to track an individual person very precisely.
This is being used to help stop the coronavirus— if a political leader rebukes people for going to beaches and parks “it won’t be based photographs or social media reports, but rather based on data from phones that recognize beach-like or park-like environments”
For context:
This article is about coronavirus, and attempts to reduce it spreading.
The government in Israel is using intrusive spy techniques --which were previously allowed for use only by a top-secret spy agency to track terrorists. This tracking follows individual citizens infected with the virus, and identifies anyone who was in physical contact with them during the previous days, so they can be ordered to quarantine. This is controversial, since it obviously is an invasion of privacy. But my post is NOT about political implications…I’m just asking about the basic facts of those 14 sensors in my cell phone.
So now, here’s my question: About those 14 sensors-- What are they, and why do Apple and Samsung build them into the phone?
I can guess at a few of them::
1.The phone’s antenna. It is constantly pinging nearby cell towers, so I assume it can define the location of an individual within a few hundred meters.
2. GPS is even more precise.
3. I can see how WifI and Bluetooth signals can also be used to help pinpoint someone’s location.
4. Ambient light detection was a new concept to me.(My own phone has only manual settings to change the brightness of the screen)
I didn’t know about automatic light detection, but I can understand why it exists, to make the screen easier to read. It never occurred to me that this would be useful to a spy agency, but I suppose it allows them to see when you move from outdoors into a building.
Now, these 4 functions I’ve mentioned are vital to the consumer who uses the phone, so of course they are built in by the manufacturer.
But what are the other 10 sensors?
The quote above mentions sensors which define “other characteristics of the environment”. What are those characteristics, and why does the phone detect them? How does it improve the phone?
Specifically–what is the “motion sensor” for? It may be useful to a spy agency, but why does Apple spend money to build it into the phone?
Proximity Sensor. Used to disable the touch screen when the phone is next to your face so that you don’t accidentally start activating apps and doing all sorts of weird things with the side of your face. Usually an IR sensor.
Accelerometer. Primarily used to detect when you tilt the phone so that it knows whether to go into portrait or landscape mode, but it detects all changes in movement so it can be used for other things.
Thermometer. May be more than one. Used to measure both the ambient temperature and the temperature of specific parts of the phone (i.e. its chips and battery to shut down in case it overheats). The ambient sensor is usually just measuring the temperature inside the case, also to prevent overheating.
Barometer. Not found on all phones. Used to detect altitude (roughly).
Humidity Sensor. Often used to make sure that the phone is not exposed to excessive humidity, as this can be damaging.
Gyroscope. Some phones have a gyroscope to also determine tilt.
Magnetometer. Used by map and compass apps.
Fingerprint scanner or retina scanner. Used for security verification.
I’m still a bit shy of your 14 total, unless they are also counting the microphone and cameras as sensors.
I don’t think they’re saying all the sensors are useful for spying. But I can see many are.
Some of those sensors include (including some that have already been mentioned):
Camera. That’s a sensor. Most phones have at least 2.
Microphone. Most phones have at least 2, the main one for phone calls and another to detect & cancel out ambient noise.
3-axis accelerometer. This measures the phone’s orientation (direction of gravity) as well as movement/vibration. Put this info through some smart software and they can determine if you are walking, running, in a car, and/or holding the phone in your hand.
Magnetometer (magnetic compass).
Gyroscope. It measures rotational movement. And by combining the data from the gyroscope and accelerometer, the phone can track its movement even without any radio signals (functions as an inertial measurement unit).
They are talking about the 3-axis accelelerometer. 3-axis means it can measure the direction (x,y,z, components) as well as the magnitude of acceleration.
Gravity is a form of acceleration, so a 3-axis accelerometer can measure the direction of gravity. I.e. it can measure which way is down. This is how it knows you are holding the phone horizontally or vertically, and rotate the screen automatically. Some games let you control the action by tilting the phone as well.
Movement is also acceleration, so the same sensor can measure movement. When you pick up the phone, the phone measures the movement (acceleration). If the phone is sitting on a solid surface, it knows that too (lack of movement).
If the phone detects it’s being moved periodically, say ~100 times a minute, it can guess that it’s being carried by someone walking. If it detects a gentle vibration combined with occasional sustained acceleration or deceleration, it can guess that it’s in a car. If it detects zero acceleration for a fraction of a second, followed by a huge acceleration, it knows it was dropped. I’m sure there are many other activities that are detectable (or at least guessable) from movement.
There are even software that tracks how much REM sleep vs. non-REM sleep you are getting, if you place the phone on the bed. Humans move differently depending on the phase of sleep.
They can also program the phone to respond to you shaking the phone. I seem to recall that touted as a feature on one of my phones.
To elaborate even more:
The 3-axis accelerometer is by far the most useful sensor in the phone.
There are huge numbers of apps that are only possible because of it - Virtual Planetarium, Enhanced VR, Pokemon Go, etc.
Since there aren’t any mobile beaches or parks I can think of, you don’t need anything more than GPS to determine where a phone has been. Wifi network names help a little for more precise localization, but not dramatically (and probably not much for beaches, which tend to be fairly light on wifi). A “beach-like” or “park-like” environment is one that has GPS coordinates that overlap a beach or park.
Hopefully the utility of having Wifi radios and GPS in phones is fairly obvious. They enable tracking but they also enable a lot of obviously useful services.
Not useful for spying, but phones can also have a TON of thermal sensors. I have this app installed on my phones, and while my Galaxy J7 Crown has “only” four listed, my Moto G(6) has twenty-five, fifteen on the CPU alone.