Two technologies sharing one characteristic: they work by announcing or detecting presence. Both their usefulness and their exposure come from there.
Understanding the mechanism serves a practical purpose: knowing what to really switch off, and what switching off achieves nothing.
It expands on the recommendation turning off Bluetooth and location.
Part 1 — Bluetooth
What it is for and how it works
It is a short-range radio technology, designed to connect nearby devices with low power use. Typical range: ten to thirty metres, far less through walls.
It works in two modes worth telling apart.
Advertising. A device periodically emits small packets saying “I am here, and I can do these things”. It is how headphones make themselves findable.
Scanning. A device listens for other devices’ advertisements and lists them.
A phone does both. And advertising is the source of the exposure described in this unit: it is a signal emitted continuously, which anybody in range can receive.
Pairing
Before exchanging data, two devices pair: they confirm they want to connect — with a code, a confirmation, or a tap — and exchange a key which they keep.
From then on they recognise each other automatically. And that is why the list of paired devices should be cleared out now and then: every entry is a stored key.
The low-energy variant
The modern version of Bluetooth is designed to use very little power, and it is the one used by watches, sensors and tags.
That has an important consequence: the energy cost of leaving it on is now very low. The “switch it off for the battery” argument is worth far less than it was ten years ago. The argument that remains is observability.
Randomised addresses
A device always emitting the same identifier would be traceable from place to place. To avoid that, modern devices periodically change the identifier they advertise, keeping it stable only towards already paired devices.
It is an effective protection and on by default on recent devices. It is not perfect — some characteristics of the signal stay recognisable — but it greatly reduces traceability.
Part 2 — Location
The four sources
A device does not use one method to know where it is: it combines several, choosing on precision, speed and power use.
| Source | Precision | Does it work indoors? | Power use |
|---|---|---|---|
| Satellites | A few metres | No | High |
| Nearby Wi-Fi networks | Tens of metres | Yes | Low |
| Mobile cells | Hundreds of metres | Yes | Very low |
| The device’s sensors | Relative | Yes | Low |
The row about Wi-Fi networks is the most interesting and the least known: the device works out its position by recognising the Wi-Fi networks it sees around it, comparing them against databases associating each network with an area.
That explains two things:
- why location works well inside a building, where satellites do not reach;
- why the system keeps scanning for networks even with Wi-Fi off: that scanning is a source of location, not an attempt to connect.
The last row of the table concerns the accelerometer, gyroscope and compass: they give no absolute position, but they allow movement to be tracked between one fix and the next.
How apps get the location
Apps do not access the sensors directly: they ask the operating system, which checks the permission granted and answers with the precision allowed.
That mediation is what makes the settings described in the operational guide effective:
| Setting | What the system does |
|---|---|
| Permission denied | It does not answer |
| Only while using the app | It answers only with the app in the foreground |
| Always | It answers in the background too |
| Approximate location | It answers with an area, not a point |
The fourth row is technically elegant: the system does not reduce its own precision — it reduces what it tells the app. The app receives a less precise value and works perfectly well for uses that do not need more.
Scheduled requests
An app can ask the system to be told when you enter or leave a certain area, instead of checking continuously.
It is an efficient and legitimate mechanism — it serves place-based reminders and arrival alerts — and it explains why an app can use location without being open, with minimal power use.
It is also what the “hollow” indicator in the status bar signals.
Power use, explained
A practical question the mechanism clears up, and one that guides choices better than any general rule.
| Activity | Power use |
|---|---|
| Bluetooth on with no devices connected | Very low |
| Bluetooth with headphones in use | Low |
| Location requested occasionally | Low |
| Continuous location from satellites | High |
| Location from Wi-Fi networks | Low |
| Scheduled requests about areas | Very low |
The highlighted row explains why navigation drains so much and a place-based reminder almost nothing: it is not the location that costs, it is the method by which it is obtained.
A useful conclusion follows: if an app you do not use appears among the top battery consumers, it is using precise location continuously. It is the quickest way to find it without opening any list.
A case worth explaining, because the mechanism is counter-intuitive and very instructive.
A small Bluetooth tag has neither GPS nor a connection. It only emits an advertisement.
Its operation rests on the network of every other device: when any phone passes nearby, it picks up the advertisement and reports its own position to the service, in encrypted form. The tag’s owner thereby sees where it is, without the phone that detected it knowing anything.
The system is designed to protect the privacy of both: whoever detects does not know what they detected, and whoever is searching does not know who detected it.
The relevant consequence is that these objects only work thanks to the participation of millions of devices — and that the same effectiveness makes them usable to follow a person. That is why the alert systems described in the unit on signals were introduced.
Why the location is sometimes wrong
A practical question the mechanism explains well, and one that helps in seeing the technology’s limits.
You are in a new place and the location shows somewhere else. The databases associating Wi-Fi networks with areas update over time. A network recently moved — an office that relocated, a router taken to another site — can still show at the previous address.
The location is imprecise indoors. Satellites do not go through roofs. Indoors the system relies on nearby networks, with a precision of tens of metres.
The location “jumps” between two points. The system is combining different sources and correcting the estimate as better data arrives.
It takes time to find you. Outdoors, after a period without using it, satellite reception takes a few seconds to establish.
You appear to be in another city. If you are connected through a VPN, some services that infer location from the network address — rather than from the sensors — will show the server’s country.
The last case is the most useful to know, because it separates two things that get confused: the location from the device’s sensors and the location inferred from the network. They are two independent mechanisms, and they can give different results at the same time.
What switching things off actually does
| Action | Real effect |
|---|---|
| Switching Bluetooth off in the settings | No advertising, no scanning |
| Switching it off from the quick panel | On some systems it stays active for system services |
| Switching Wi-Fi off | No connection, but the scanning can continue |
| Turning off network scanning | It stops the scanning with the radios off too |
| Flight mode | It switches off every radio |
| Revoking a location permission | The app no longer gets an answer from the system |
| Turning location off | No app receives the position |
Rows two and three are why this technical unit is useful: two of the actions people take most often do not do what they think.
How the system protects your location, without you knowing
It is worth recognising the protections already active, because there are more of them than people think and they explain why the situation has improved.
Permission is mediated. No app accesses the sensors: it asks the system, which decides what to answer. It is the structural protection everything else rests on.
Permission is revocable at any moment, and the revocation takes effect immediately.
Access is flagged. The status bar indicator makes visible something that used to be invisible.
Background access is remembered. The periodic notification summarising which apps used location while closed is a recent and very effective feature.
Precision can be reduced. The approximate option allows you to grant without granting everything.
Permission can expire. On some systems, an app unused for months automatically loses the permissions granted — maintenance that happens on its own.
Identifiers rotate. Bluetooth and Wi-Fi periodically change the identifier they advertise, making it harder to follow a device between places.
Taken together, these protections describe a clear direction: operating systems have moved towards giving the user control, and tools for exercising it.
What is missing is not the technology: it is the moment when somebody opens those lists. And that is exactly what this semantic unit tries to provide.
How this connects to the Cyber Welfare Framework
| Pillar | What this content contributes |
|---|---|
| Skills | Understanding which actions really switch off what |
| Awareness | Knowing that location is also derived from nearby networks |
| Secure Behaviour | Clearing out the paired devices and using approximate location |
Reference level: FL3 — Autonomous.
Summary
- Bluetooth advertises its presence continuously: that is where the exposure comes from.
- Location comes mainly from nearby Wi-Fi networks, not from satellites.
- Approximate location reduces what the app receives, not the system’s own precision.
- Switching off from the quick panel often does not really switch off: you have to go through the settings.
One thing to do today. Open your Bluetooth settings and look at the list of paired devices. Every entry is a stored key: remove the ones for devices you no longer own.
Related content
- Turning off Bluetooth and location — the recommendation this expands on
- How to manage connections and location — where to act, in practice
- Impact of always on connections — what continuous advertising leads to
- Bluetooth attacks — what exploits these mechanisms
Related resources
Short reads from the Resources section, for anyone who wants to stop on a single aspect:
Start with the first step: the Cyber Welfare Programme guides you free of charge, one recommendation at a time.
