- #1
CMW328i
- 8
- 1
Hi all, Teacher here looking for some guidance. I'm teaching a class that I took myself a few years back, and I'm looking at my solution to a problem but I have a random value in my answer (which I know to be correct) but I can't for the life of me remember where this value came from! Can anyone help?
1. Homework Statement
A receiver in a digital mobile communication system has a noise bandwidth of 200 kHz and requires that its input SNR should be at least 10 dB when the input signal is -104 dBm.
What is the maximum permitted value of the receiver noise figure?2. Homework Equations
FdB = Ps -SNR -10log (kTB)
3. The Attempt at a Solution
FdB = (-104 -30)-10 -10log (1.399x10^-23*290*200000) = 6.9 dBI can't for the life of me figure out where the -30 comes from. I even have an excerpt from the book the question came out of and it just shows the -30 in the equation without explaining where it comes from. Any ideas?
I see the input at -104, I see the bandwith, the required SNR, but no origin for -30
1. Homework Statement
A receiver in a digital mobile communication system has a noise bandwidth of 200 kHz and requires that its input SNR should be at least 10 dB when the input signal is -104 dBm.
What is the maximum permitted value of the receiver noise figure?2. Homework Equations
FdB = Ps -SNR -10log (kTB)
3. The Attempt at a Solution
FdB = (-104 -30)-10 -10log (1.399x10^-23*290*200000) = 6.9 dBI can't for the life of me figure out where the -30 comes from. I even have an excerpt from the book the question came out of and it just shows the -30 in the equation without explaining where it comes from. Any ideas?
I see the input at -104, I see the bandwith, the required SNR, but no origin for -30