Iecep Comms Reviewer - 1. Noise

Sample problems to guide you kung ano yung mga important Comms formulas. Try to solve on your own tapos comment niyo dito yung mga answers niyo. After ilang days, sasabihin ko yung sagot at yung important formulas. :)

A. NOISE 1. What is the capacity of a 4MHz channel at an SNR of 3dB?

 =  +   Where BW = bandwidth SNR = absolute value, not dB value

 = 4 log2 1 + 100.3   = 6.33

2. What is the noise power in Watts of a system with BW 6MHz at 600K?

 =  Where k = Boltzmann constant T = temperature in Kelvin BW = Bandwidth

 = .  3. Calculate the noise figure of a system with 22dB SNR at the input and 4 dB SNR at th e output.

 =

 

 = 22 − 4  =  4. Calculate the equivalent noise temperature of the system with a noise factor of 2.2.

 =   +   Where: To = reference temperature. If not given, To = 290K NF = noise factor/noise figure

 = 928 5. Calculate the overall noise factor of a cascaded 3 -stage system with: NF1 = 3, G1 = 2, NF2 = 1, G2 = 4, NF3 = 6, G3 = 2.5

 −   −  + +⋯    ′

 =  +

 = 3 + 

1−1

+

6−1

2 2(4) = 3.625

6. What is 45 dBm in dbrn? dba?

 =  +  (above reference noise)  =  +  (F1A weighted) 45 dBm = 135dBrn = 130dBa