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Communication Systems Engineering Episode 1 Part 7

Tham khảo tài liệu 'communication systems engineering episode 1 part 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Eytan Modiano Slide 1 Lectures 8-9 Signal Detection in Noise Eytan Modiano AA Dept. Noise in communication systems S t Channel ffi----- r t L k r t S t n t n t Noise is additional unwanted signal that interferes with the transmitted signal - Generated by electronic devices The noise is a random process - Each sample of n t is a random variable Typically the noise process is modeled as Additive White Gaussian Noise AWGN - White Flat frequency spectrum - Gaussian noise distribution Eytan Modiano Slide 2 Random Processes The auto-correlation of a random process x t is defined as - Rxx t1 t2 E x t1 x t2 A random process is Wide-sense-stationary WSS if its mean and auto-correlation are not a function of time. That is - mx t E x t m - Rxx t1 t2 Rx T where T M2 If x t is WSS then - Rx t Rx -T - Rx t Rx 0 max is achieved at T 0 The power content of a WSS process is Px E lim 4 ÍT x t dt lim 4 ÍT 2 Rx 0 dt Rx 0 t T - T 2 t - T - T 2 Eytan Modiano Slide