CODEWITHSUNDEEP
iosbluetooth-lowenergy
Gilles Lesire
Gilles Lesire

Reputation: 1237

Objective-C iOS 6 BLE (Bluetooth 4.0) Distance calculation

Is it possible to calculate the distance between the device and the iPhone, or at least, have an idea of the strength so I can check if the distance is getting smaller or bigger as I move. I would like to build some sort of system which makes it easier to find "lost" things in a close perimeter.

Is such thing possible? And if so, what is the best way to do this.

I assume that there is no obstruction between the two devices.

Upvotes: 3

Views: 8131

Answers (1)

RowdyRobot
RowdyRobot

Reputation: 126

Yes, absolutely!

Actually it's basic functionality provided by Core Bluetooth. To reference a link provided by a previous answer:

As soon as a Peripheral is discovered during the scanning, the Central delegate receives the following callback:

  • (void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI

This call notifies the Central Manager delegate (the view controller) that a peripheral with advertisement data and RSSI was discovered. RSSI stands for Received Signal Strength Indicator. This is a cool parameter, because knowing the strength of the transmitting signal and the RSSI, you can estimate the current distance between the Central and the Peripheral. So, you can use the distance as a filter for a given service: only if the Central is close enough to the Peripheral, then your app does something.

The RSSI value allows you to estimate the distance, create virtual fences and can also be used to zero-in on a BLE device by comparing the new RSSI measurement to the previous one.

Upvotes: 5

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