HOW TO CALCULATE RSSI USING TX POWER AND INSTANT RSSI VALUE AND ENVIORNMENTAL FACTOR

[Embel_Tech]

Hello,

I want to calculate RSSI using TX power(Measured power at 1m) and  instant RSSI getting in NRF CONNECT APP  and Environmental factor.

I have used   this 

           Distance = 10 ^ ((Tx – RSSI)/(10 * N))        WHERE     TX -POWER AT 1METER,N- ENVIRRNMENTAL FACTOR,RSSI VALUE FROM NRF APP.

but calculation are wrong/ not matched with expected .

Let me know the what needs to do in this case also environmental factor what needs to be set.

[dejans]

HI,

Could you provide the values for the parameters that you included in your calculation?

Could you please also provide more information about your testing environment?

calculation are wrong/ not matched with expected

Can you provide more information why you think that calculations are wrong? Could you specify what is expected?

Best regards,
Dejan

[Embel_Tech]

Hi,

Distance = 10 ^ ((Tx – RSSI)/(10 * N))   

For example 

  if i m taking readings for beacon interval of 5 sec my observation is...

   -> getting rsssi value for 3 meter is -66.5 

  -> Tx(by observation 1 meter rssi) is -56.2

  -> if taking N is 2 or 3 or 4 

my calculated distance is  not showing expected distance 3 or approx. 3 meter

so how to fix formula or value of N.????

[dejans]

Hi,

If you calculate as shown below with N=2, 

distance = 10^((-56.2+66.5)/(10*2)) = 10^(10.3/20) = 3.27 m

If you choose bigger N, you are expected to get smaller distance.

Although distance measurement based on RSSI can provide some approximate distance estimate, the distance value will not be accurate as path loss factor N depends on the environment. 

Best regards,
Dejan