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(This semester there are about 150 students in my classes. I am not able to handle students' questions via email. It may take at least 10 minutes to handle one student's question. You know what I mean .. ^^)
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Thanks,
[Question]
강의자료(long version) 12페이지의 수식을 보면, Nmax = 1/c * B * r이라는 식이 나와있는데, ( 첫번째 식 )
8페이지에 나와있는 data rate, signal rate 관련 식을 보면, S = c * N * 1/r인 식이 나와있습니다. ( 두번째 식 )
두번째 식을 정리하면 N = 1/c * S * r으로 바뀌는데, 이것과 첫번째 식을 비교하면,
Nmax = 1/c * B * r
N = 1/c * S * r이 됩니다.
S는 signal rate(baud rate)라고 배웠는데, 왜 이렇게 S와 B가 같게 되는 지 모르겠습니다.
Bandwidth, Signal rate는 단위부터 다른데, 이 부분이 헷갈립니다.
- We can say that the baud rate determines the required bandwidth for a digital signal: More changes in the signal mean injecting more frequencies into the signal. (Frequency means change!! change means frequency!! Namely, baud rate and frequency imply that some change rates per second)
- From the lecture notes, each level corresponds to one signal element.
- From 1 and 2, we can roughly say that the bandwidth (range of frequencies) is proportional to the signal rates (baud rate).
- Thus, the minimum bandwidth can be given as,
- S is proportional to B.
- B_min = c X N X (1/r) ⇒ B ≤ c X N X (1/r) ⇒ (1/c) X B X r ≥ N (= N_max)
[Problem 37] Errata
Signal 10V -> 10W
Signal 5mV -> 5mW
