Just a little confused...
I know that this is so rudimentary. However, my professor made this comment and I am really struggling trying to figure it out myself.
Let's say that I have a signal in the time domain that looks like this:
f(t)
_____
| __/ _
| _/
| _/
|
| t-> | | |
Now, let's say that we sample this signal with the ideal sampling function (comb) delta(t + nTs) [-inf < n < +inf]:
delta(t + nTs)
|
|
|
^ ^ ^ ^ ^ ^ ^
||||||__| | t-> | |
Now, the sampled result is delta(t + nTs) X f(t), which results in:
delta(t + nTs) X f(t) ==> x(t)
| . . . | . . . | . . . |
| u-> | | |
Okay, so I know a few things. I know that f(t) has a maximum frequency and is therefore band limited in the frequency domain. It is not, however, time limited since both the sampling function and f(t) exist for all t (given the constraints of the sampling function).
So, here is the part that confused me: Even though x(t) is not continuous in the time domain, it is continuous in the frequency domain, where F(w) is:
F(w)
|
|
/ \ / |\ /
/ \ / | \ / \
/_../|____/___
| |<-1/Ts->| w->
|
|
Is F(w) continuous only because F(w) = 0 over the bandwidth 1/Ts?
I think I just answered my own question. Thanks r/dsp!
Posted Dec 2, 2011, 12:41 AM UTC