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Jan28-12, 03:49 PM   #1
 

aliasing and discrete sinusoids...


Hello Forum,

a continuous time, continuous amplitude sinusoid like sin(2pi*f*t) is 2pi periodic:

sin(2pi*f*t)=sin(2pi*f*t+m*2pi)

where m can be any positive or negative integer. Let's sample the sinusoid at a sampling frequency fs (sample interval is ts=1/fs) and get the discrete signal

x[n]=sin(2pi*f*n*ts)=sin(2pi*f*n*ts+2pi*m)=sin{2pi(f+m/(n*ts))*n*ts}

This book says: if we let m be an integer multiple of n, m=k*n, we can replace the ration m/n with k so that

x[n]=sin(2pi*f*n*ts)=sin{2pi(f+kf*s)n*ts}

What happens if m is not an integer multiple of n? Both m and n are integers (I get that), but I don't understand the constraint m=k*n....That does not seem general enough.....

thanks
fisico30
 
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