How to get accurate distance frequently

[Miteshmakwana73]

i am trying to get distance but not getting accurate result every time.

if i place beacon and mobile in stable place it's changing distance value how can i avoid that.

this is my code for get distance

fun calcDistbyRSSI(rssi: Int, measurePower: Int = -59): String? {
        val iRssi = Math.abs(rssi)
        val iMeasurePower = Math.abs(measurePower)
        val power:Double = (iRssi - iMeasurePower)/(10*2.0)
        // ft = m * 3.2808

        if (Math.pow(10.0,power) * 3.2808 < 1.0){
            return String.format("%.2f ft(Immediate)", Math.pow(10.0,power) * 3.2808)
        }else if (Math.pow(10.0,power) * 3.2808 > 1.0 && Math.pow(10.0,power) * 3.2808 < 10.0){
            return String.format("%.2f ft(Near)", Math.pow(10.0,power) * 3.2808)
        }else{
            return String.format("%.2f ft(Far)", Math.pow(10.0,power) * 3.2808)
        }
    }