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i was making an indoor positioning system using bluetooth HC-05 and i was wondering if i can use the rssi reading from 3 static beacons will remain inside a certain zone inside a certain range of readings ? for example if i have 4 rooms and i will take the reading of rssi from 3 bluetooth beacons hc-05 modules and check the minimum and maximum for each room while a person moves with an hc-05 module inside a room when done moving i will record the max and min reading of RSSI for each room then when trying to identify a new location i will compare the current reading of RSSI with the previously recorded data to see to which range the new reading belongs to . meaning for the current reading of 3 beacons compare the value to check in which range it falls among the 3 beacons they will fall in a certain range for a certain room then this is my zone . is that correct and how can i enhance ?

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    \$\begingroup\$ how can i enhance ? - better grammar, capitalization and punctuation with the odd paragraph break would be a good start. \$\endgroup\$ – Andy aka Jul 7 '17 at 11:49
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    \$\begingroup\$ Take lots of measurements. You then become the expert. The walls will affect the signal, as will metal screens inside walls of bathrooms, or on exterior walls where cement is applied. \$\endgroup\$ – analogsystemsrf Jul 7 '17 at 14:56
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Because BT uses frequencies in the 2.4 GHz region, you will find that the RSSI is subject to attenuation by the human body and other objects in the field. Reflections can also produce odd results. Adding more beacons can help to mitigate these effects.

It may work to some degree but you will find it to be less than reliable.

Edit: As you work on your RSSI algorithm, don't forget that signal strength is inversely related to the distance squared. So if you double your distance, the signal strength will be 1/4 of what it was.

Also check to make certain you know the units/scale by which RSSI is reported by your devices. It sometimes is linear and in other cases it is logarithmic. It would be best to do some range testing to develop your own calibration for RSSI for the particular device.

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  • \$\begingroup\$ my basic idea for the algorithm now is to make a kind of learning algorithm , identify a zone by making the person move inside it and measure the RSSI of the signal from 3 bluetooth beacons determine the max and min reading of that zone for each of the three beacons repeat for a couple of zones then after that stage has been finished when the person moves to 1 of the zones take a voting based on the RSSI , for example beacon 1 would vote this might be zone a or b beacon 2 would vote b or c and beacon 3 would vote all a,b,c since b has greatest votes then zone is probably b \$\endgroup\$ – Essam Eid Jul 8 '17 at 11:23

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