NAV-06 · Lesson 08

Device Security and Emissions Control

What the thing in your pocket keeps, what it sends, and who ends up holding a record of where you have been.

Reading: about 10 minutes · Field drill: about 30 minutes

Bottom Line Up Front

A navigation device is a recording instrument. That is not a side effect — recording is how retracing works, how routes get reviewed, and how a track becomes evidence you went where you said. The same capability produces a detailed, timestamped account of your movements, and on some devices ships it somewhere.

The aim here is not paranoia and it is not switching everything off. It is knowing, for each device you carry, what it stores, what leaves it, and what you can turn off without losing the capability you actually need. Then deciding that deliberately instead of by default.

Recall Check · L05

From Lesson 05, because this lesson is about what the device keeps: what is a recorded track actually made of?

A. A continuous trace of the path walked, sampled finely enough that the recorded line matches the ground.
B. The turning points of the route being followed, logged automatically as each one is reached.
C. The positions the device chose to keep at its recording interval, joined by straight lines.
D. A position every second, with the device discarding duplicates when movement stops.

1. What a device knows about you

Work through your own gear against this list rather than assuming.

What it holds	What it reveals
Recorded tracks	Where you went, when, how fast, how often. Weeks of tracks show routine: when you leave, which way, how long you are away.
Stored waypoints	What matters to you, and frequently what it is, because people name things honestly. A point called CACHE-N is a sentence.
Geotagged photos	Position and time in the file, carried along invisibly when the photo is shared.
Routes and plans	Intent. Not where you have been but where you are going, which is the more sensitive of the two.
Account and sync history	All of the above, on somebody else’s server, retained under their policy rather than yours.
Live sharing sessions	Position in near real time to whoever holds the link, for as long as the session runs.

The row that surprises people is the first one, because a single track looks harmless. Aggregation is the issue: any one outing is unremarkable and a season of them is a pattern of life — the times, the routes, the gaps. That is a different and more useful thing to anyone interested in you.

Knowledge Check

Why is a season of ordinary recorded tracks a bigger exposure than any single one of them?

A. Older tracks were recorded before current settings were applied, so they carry data the device no longer collects.
B. Storage fills as tracks accumulate, and a device near capacity writes less reliably and holds partial files.
C. Together they show routine — times, routes, absences — which no single unremarkable outing reveals.
D. Tracks are stored with higher precision than positions passed by radio, so archived files are inherently more revealing.

2. What actually transmits

A common and comfortable belief is that a satellite receiver is silent. As a receiver, it is: computing a position involves listening only, and nothing about a fix is broadcast anywhere.

What may transmit is everything else in the same case. A phone is a radio first and a receiver second, and it is in contact with the network continuously regardless of any positioning setting. A handheld with wireless features can be paired, syncing, or sharing. A watch relays through a phone. The receiver is silent; the device around it usually is not.

Separate two questions that get merged. “Does this device reveal my position by computing a fix?” — no. “Does this device reveal my position?” — that depends entirely on its radios, its accounts, and its sync settings, and the answer is often yes.

Knowledge Check

A member argues that using GPS cannot give away their position because the receiver only listens. Where does that reasoning break down?

A. It is correct about the receiver but says nothing about the phone, radios, accounts and sync in the same device.
B. It is wrong at the root, because a receiver must transmit a brief acknowledgment to the constellation to obtain a fix.
C. It holds only above a certain accuracy setting, below which the device requests assistance data over the network.
D. It ignores that receivers emit detectable local interference, which direction-finding equipment can locate at short range.

3. Sanitizing, before and after

Two moments deserve a deliberate pass over the device, and they are different from each other.

Before movement

Ask what is on this device that should not travel with it. Old tracks that show home, waypoints named too honestly, cached routes to sites unrelated to this trip. If the device is lost, captured, or simply looked at by somebody at a checkpoint, that is what they get. Carry what the trip needs.

Then set the posture: sharing off or on, sync on or off, recording on or off, and the radios that are not needed switched off — which also buys battery.

After movement

The other pass is the one people skip. Get the track off the device and onto storage you control, then clear it. Rename anything you named hurriedly. Strip position data from photos before they go anywhere, because that metadata travels with the file and outlives the conversation it was shared in.

Sync is a decision, not a feature

Cloud sync between phone, web and handheld is genuinely useful — it is how a route built at a desk reaches a device, and how a group shares points. It also means your waypoints, routes and tracks exist on a company’s servers, tied to an identity, with timestamps, retained under a policy you did not write and can change.

Neither on nor off is the right answer for everyone. Knowing which one you are in, per device, is not optional — and if you do not know, assume it is on, because that is the default.

Knowledge Check

Which sanitizing step is most often skipped, and why does it matter after the trip is over?

A. Switching the radios off before departure, because a device left connected drains battery that the trip will need later.
B. Confirming the datum matches the map, because a mismatch discovered afterwards invalidates every position recorded on the trip.
C. Clearing the device afterwards, because the record of where you went stays on it and accumulates into a pattern.
D. Reviewing the recorded track against the plan, because errors that are not identified soon after will be repeated.

4. When the device goes off

Emissions control is a posture the whole group adopts together, and navigation sits inside it. Three positions cover most needs.

Posture	Navigation
Unrestricted	Devices on, sharing and sync as normal. Convenience wins because nothing is at stake.
Restricted	Receivers on, recording as required, but sharing and sync off and radios that are not needed switched off. This covers most serious movement.
Silent	Transmitters off entirely. A handheld may still be used to receive, or the whole thing goes off and you are on map and compass.

Two things make this workable rather than theoretical. The group agrees the postures and their triggers in advance, so “go restricted” is one instruction rather than a negotiation. And the navigation plan has to survive the strictest posture you might adopt — which means the paper map, the marked route and the written grids, because a plan that only exists on a device you have just turned off is not a plan.

That last point is where this lesson meets the rest of the course. Every argument for map and compass so far has been about the device failing. This is the case where it works perfectly and you turn it off on purpose.

Knowledge Check

What has to be true before a group can adopt a silent posture without losing its ability to navigate?

A. Every member must carry a second receiver, so that a device switched off can be replaced by one still permitted to operate.
B. Tracks must be recorded up to the moment of going silent, so the retrace function still covers the route in.
C. Devices must be switched to receive-only mode, which preserves navigation while removing the transmitting capability.
D. The plan must already exist off the device — paper map, marked route, written grids — before the posture changes.

What to carry out of this lesson

One track is unremarkable. A season of them is a pattern of life, and that is information none of the individual files contain.
Receiving a fix is passive and reveals nothing. The phone, radios, accounts and sync around the receiver are a different question, and usually the answer is yes.
Sanitize after movement, not just before. The pass people skip is the one that stops the record accumulating.
The plan has to survive the strictest posture you might adopt. A route that exists only on a device you just switched off is not a plan.

Field Drill

Inventory before opinion.

For each device you carry, write down what it stores, what leaves it, and where that goes. Where you cannot find out, write that — an unknown is a finding.
Look at your saved waypoint names as though you had just found the device in a ditch. Rename anything that reads as a sentence about you.
Take a photo with your phone, then check whether position data is in the file. Then find the setting that controls it.
Write the three postures for your group, with the trigger for each, in plain language somebody can be told over a radio.
Test it: adopt the silent posture for one movement and navigate the whole leg from paper.

The postures go into the group standard in Lesson 10.

Answer all four knowledge checks to unlock Lesson 09

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