How to measure distance between two iphone devices using bluetooth?

Question

Hi, Everyone,

I'd like to do something in the following using bluetooth.

1. Measure and display how far my iPhone is from another iPhone.
2. Display direction of my iPhone.

For example,

I'd like to display something in the following on my iPhone application.

My iPhone is connected to another iPhone:Harry's iPhone.

In this case,

• Distance : 3m 45.3cm (Accuracy:milimeter)
• Direction : North East(one of 8 available directions)

Does anyone know how to do this? If I get the answer, that'll be very thankful.

Expect good news.

Thanks.

Answer 1

For direction, you would have to hold the phone away from you and spin in a circle allowing the phone to measure the increase/decrease in signal strength. Not sure how good the iPhone signal reception will be.

You could estimate the distance by looking at the signal receive strength. You will have to perform many tests, in different environments in order to get some half decent metrics to use within your app.

Answer 2

Using bluetooth for localization is a very well known research field (ref.). The short answer is: you can't. Signal strength isn't a good indicator of distance between two connected bluetooth devices, because it is too much subject to environment condition (is there a person between the devices? How is the owner holding his/her device? Is there a wall? Are there any RF reflecting surfaces?). Using bluetooth you can at best obtain a distance resolution of few meters, but you can't calculate the direction, not even roughly.

You may obtain better results by using multiple bluetooth devices and triangulating the various signal strength, but even in this case it's hard to be more accurate than few meters in your estimates.

Answer 3

You can't do this with bluetooth. You could meassure the distance between two BT devices by analysing the BT reception quality - but this will strongly differ in every new environment (e.g. simply a new room or in the open air). For direction: here is exactly the same problem, especially inside buildings. A lot of BT signal echos will make it almost impossible to receive useful direction data. There are ways to determine distance and directions via wireless connections (doesn't matter if BT, WLAN or ZigBee or something else) - not with standard customer devices, but with real-hitech laboratory equipment.

Answer 4

Hi sir, i am a student and working on a similiar problem statement, your answers and suggestions would be of great help to me,

i want to know that if i have to calculate distance between two bluetooth devices with a maximum distance seperation of say 500 cms or 0.5 meteres, would it be possible to get accurate measurements based on signal strength of two bluetooth connected devices.

awaiting your answer, thanks