Regarding nRF51822 RSSI to Distance Calculation

[Nazmus Sakib]

Hi All.

I made my PCB with nRF51822 and achieved around 150 Feet range (LoS). My target is to calculate a approximate distance (in Feet) from RSSI values.

I did a field test and measured some data and observed its quite non-linear to determine a distance value. My test data is attached herewith.

Any anyone please advise the best way to formula to calculate distance from RSSI under open field?

Thanks in advance.

Regards.

[Dan Danknick]

It's just a simple infinite impulse response filter using fast integer math.

The equivalent with floating point, which you more typically see, is:

strength = 0.0625f; signal = (1.0f - strength)signal + strengthnew_signal;

Dan