27th June 2010 at 14:48
#59366

NA

Guest

The formula for W to dBm conversion is X (dBm)=10 log Y (mW)

so when we convert the smaller power as 0.3 mW

that will be written as :-

X dBm = 10 log 0.3

= 10 log 3^(-1)

= – 10 log 3

= – 10*0.477

= – 4.77 dBm

gives 0.3 mW = -4.77 dBm

so, it is clear here why -ve sign pops out to the value when we calculate the Rx level, as Rx level is always smaller, but Tx is always +ve because it is near the transmitter giving much power.

thanx