a problem

[ameetsurvey]

Can someone please give me the answer of following question.

the transmitter operates at a frequency of 1GHz, it is connected to an antenna of gain 10dB. the cable connecting the transmitter to the antenna has a loss of 3dB. the reciever has an antenna with a gain of 0dB and there is no other loss at the reciever. the distance between the transmitter and the reciever is 6km. the double sided noise power spectral density at the reciever, No/2 is 10e-16 W/Hz. assuming free space path lose between the transmitter and the reciever antennas. calculate the power needed at the transmitter to maintain a demodulater BER of less than 10e-3  ?

 

[prateeksikka]

GAIN IS SIMPLY ADDED IN TERMS OF decibels.

10dB gain and a 3dB loss accounts for a net gain of 7dB for the receiver...
Free space has a trasfer function of 1.so the power spectral density at the receiver  is the same as that at the transmitter.
Assuming FSK transmission
Probability of error=1/2*erfc(0.6*Es/No)
if u are using ASK then 0.6 is replaced by 0.25
it is 1 for PSK.
For a giver BER i.e probability of error u can get signal energy....