What are the nominal distances for iBeacon "Far", "Near" and "Immediate"

Question

I played with iOS devices with both broadcasters and receivers using the new iBeacon API in iOS 7.

Documents do not go into details at what distances each proximity indicator should see the receiving device, and specifically calls them "relative." When experimenting with a demo application, I observed these distances (iPhone receiver ==, iPad broadcast ==):

Far 50 feet?

Nearby - 2-3 feet

Immediate - 2 inches

It seemed to me that this is very small, and perhaps there is a hint of a CLBeaconRegion class link that allows you to specify the signal level of your device from a distance of 1 m.

peripheralDataWithMeasuredPower:

Retrieves data that can be used to advertise the current device as a beacon.

Options

measuredPower

Received Signal Strength Indicator (RSSI) value (measured in decibels) for the device. This value is the measured beacon strength of one meter and is used during ranking. Specify nil to use the default value for the device.

My amateur calibration gave -60, which I installed and checked:

Far - hundreds (ish) feet

Nearby - ~ 50 feet

Immediate - 1 meter (slightly less)

Are the results of my second test “ideal” ranges according to Apple? They are really far from the default settings that I tested in the first test.

Or should I perhaps consider these ranges to be “calibrated” depending on my needs?

Answer 1

From what I understood from the API, there is never a guarantee at the actual distance, you should not use readings that should be considered accurate measurements. Proximity is rather used to determine the relative distance between different beacons so that you can respond accordingly based on the requirements of your applications.

With that said, Apple definitely paints a gray space in its documentation. Description measuredPower intriguing and easy to suggest that you can use this value to get an accurate reading of the distance (of course, calibrated). I just don't think so, however, with the likelihood of signal attenuation in these very low power devices, I don't expect you to get accurate readings of the actual distance.

From the CLBeacon reference, the accuracy description reads

Indicates one horizontal sigma precision in meters. Use this property to distinguish beacons with equal cost proximity. Do not use it to determine the exact location of the beacon. Accuracy values ​​may fluctuate due to radio frequency interference .

I feel this inexplicably resonates throughout the use of the iBeacon function.

This is all my interpretation, I did not go as easily as testing it in several environments over time to see if consistent readings are given. I'm not sure if this helps at all.