Noise reduction and square wave/sine function questionby niteshadw Tags: function, noise, reduction, square, wave or sine 

#1
Dec1806, 11:04 PM

P: 20

I have two simple questions but I'm not 100% on how to get the correct result.
1. "The noise is reduced by 6 dB" means its amplitude is cut to _%? How is it calculated to 50%? I try 20log(Av)... 2. Does this wave contain 30k hertz sine function? (see attachment) The answer is yes, but I try f=1/T, in this case T = 0.1 ms, so f is 10k, how is it 30k? Thank you 



#2
Dec1906, 04:13 AM

P: 460

[tex]20 \log(A_v) = 6 \Rightarrow A_v = 10^\frac{6}{20} \approx .50 [/tex] [tex] f(t) = \sum_{k=1,3,5...}^{\infty} b_k \sin(k(10k)t)[/tex] Notice that one of the terms in the series is a sine term which has a frequency of 30kHz. 



#3
Dec1906, 07:57 AM

P: 20

Thank you very much, that was much of a help! =)




#4
Dec1906, 10:13 AM

Mentor
P: 39,628

Noise reduction and square wave/sine function question 


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