If you ever watch crime film or series, you’ll have seen parts where the police track down a suspect using the location of their phone. In this video we’re going to look at how that works.
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Cell phone are constantly in contact with cellular networks when switched on. Cellular networks are divided into cells (this is where the name cell phone comes from). Each cell is served by a cell tower or base station. The size and shape of a cell depend on factors like population density and terrain.
Mobile devices communicate with the network by connecting to the nearest cell tower. All phones send periodic signals to the nearest cell towers even when not making a phone call. They do this to ensure they are connected to the nearest tower for optimal performance. This also how your device always knows how strong its signal is. If you enter a tunnel and look at your phone you’ll see it quickly detects it has no signal or service, it knows this as its tried to communicate with the nearest cell tower but had no response as the tunnel is blocking its communication being sent. As a device moves, it may switch to a different tower when it enters a new cell to ensure you still have service. Each cell tower covers a specific geographical area and is identified by a unique combination of a Location Area Code and a Cell ID. The LAC represents a broader location area, and the Cell ID identifies the specific cell within that area.
When a mobile device communicates with a tower, the network logs the LAC and Cell ID, creating a record of the device's location. This record is kept by the cell service provider.
The cellular network constantly measures the signal strength of a mobile device as it communicates with nearby towers. Signal strength is used to estimate the distance between the device and each tower.
If we think back to a crime show scene and imagine the police want to get a suspect’s phone location to track them down.
The police will first approach the suspects cell service provider with a warrant requesting them to share the data they have on the suspects device. The cell provider then checks their logs that show when a device with the number registered to the suspect communicated with cell towers and which cell towers those were. The logs will also show the signal strength between the phone and the tower each time the phone communicated with the tower, the signal strength indicates the distance the phone was from a tower. By analysing the signal strength from multiple towers, they can triangulate the device's location. If we say it was 1 mile from tower A we know the phone was somewhere along the line of this circle. If it was 2 miles from tower B at the same time we know it was in one of the positions where the 2 circles overlap. If the phone was also 1 mile from tower C at the same time we can see there’s only 1 location where all 3 circles overlap each other. This points to the location the phone was or is at this particular time.
Its worth noting this method of tracking only works if a cell service provider can match a phone number to a customer or suspect. This is why we often see criminals in films use a prepaid burner phone as it means the cell service provider cant match the phone number to a person as the criminal has not provided personal information to the cell provider like you would when taking out a regular contract.
Does cell service providers having access to your location concern you and how do you think they should manage that data? Please do subscribe if you’ve enjoyed this video ad thanks for watching!
#phonetracking #phonetapping #triangulation
28 июн 2024
