1. Komunikasi Digital
Minggu ke-2

2. Pertemuan 2

3. ANALOG & DIGITAL MESSAGE
Digital message adalah deretan simbol
yang merepresentasikan informasi

4. Digital communication?

5. Why digital communication?

6. Regenerative repeater in DC

7. Blok diagram siskom
Synchronization hanya ada di digital communication

8. Digital vs Analog
Advantages:
• Digital signals are much easier to be regenerated.
• Digital circuits are less subject to distortion and
interference.
• Digital circuits are more reliable and can be produced at a
lower cost than analog circuits.
• It is more flexible to implement digital hardware.
Disadvantages:
• Heavy signal processing.
• Synchronization is crucial.
• Larger transmission bandwidth

10. Himpunan
1. Himpunan  Kumpulan objek (sesuatu )
2. Objek  elemen
3. Universal set/ space : setiap himpunan adalah
subset universal set  A  S
4. Null set – set tanpa elemen    A
5. Union/ sum : u
6. Intersection
7. Complement
8. Difference
9. Transitivity
10. Equality

11. Sample space & probability
• Random experiment: its outcome  cannot be predicted
with certainty  setiap data pengamatan yang mungkin
munsul dari experimen tersebut.
• Sample space: the set of all possible outcomes .
• Outcome can be  mutually exclusive & collectively
exhaustive.
• Events are subsets of the sample space for which measures of
their occurrences, called probabilities, can be defined or
determined  himpunan outcome-outcome experiment

12. Example:
Various events can be defined: “the outcome is even number of
dots”, “the outcome is smaller than 4 dots”, “the outcome is more
than 3 dots”, etc.

13. Himpunan dan probability
Himpunan Probabiltas
Himpunan / Set Event
Universal set / Space S Sample space
Element Outcome
EventHimpunanoutcomedalamexperiment
Setiapsubsetsamplespaceadalahevent
Jumlahoutcome :l…I=n

14. Three Axioms of Probability
• Ukuran peluang P (.) adalah sebuah fungsi yang
memetakan event-event dalam sample space ke bilangan
riil sehingga memenuhi aksioma-aksioma :
• Aksioma 1 : Untuk setiap event A, P (A)  0
• Aksioma 2 : P (S) = 1
• Aksioma 3 untuk kumpulan terbatas A1,A2,… event-even
mutually exclusive ( outcome tidak muncul bersama).
• Aksioma 1 & 2  Peluang adalah bilangan antara 0 dan 1

15. Important Properties of the
Probability Measure

16. Teorema :
1. Bila event-event A dan B, A B = , maka P (A  B ) =
……
2. Bila B = B1  B2 … Bn dan Bj =  untu ij, maka P
(B) = 𝐼=1
𝑀
𝑃(𝐵1)

17. Random Variables
• A random variable is a mapping from the sample space to
the set of real numbers.
• Shall denote random variables by boldface, i.e., x, y, etc.,
• while individual or specific values of the mapping x are
denoted by x(!).

18. Random Variable in the
Example
• There could be many other random variables defined to
describe
• the outcome of this random experiment!

19. A random variable can be
discrete, continuous or mixed.

21. • Bit merupakan istilah khas pada sinyal digital. Sebuah bit
dapat berupa no; ( 0 ) atau ( 1 ), sehingga kemungkinan nilai
untuk sebuah bit adalah 2 buah ( ). Kemungkinan nilai untuk 2
bit adalah sebanyak 4 , berupa 00, 01, 10, 11. Secara umum,
jumlah kemungkinan nilai yang terbentuk oleh kombinasi n bit
adalah sebesar 2n buah.
Komunikasi digital