1. CSE 313 Data Communication
Lec 11
Sabbir Muhammad Saleh

2. Data Element Versus Signal Element
A data element as the smallest piece of information to be exchanged in the digital system, that is the bit.
A signal element as the smallest unit of an analog signal that is constant. It forms a unique pattern.
Figure on the next slide has a visual representation of the digital and signal elements.
PG:136 Data Communications and Networking By Behrouz A.Forouzan 5th Edition.

3. Data Element Versus Signal Element
PG:136 Data Communications and Networking By Behrouz A.Forouzan 5th Edition.

4. Data Rate Versus Signal Rate
We can define the data rate (bit rate) and the signal rate (baud rate) as we did for digital transmission. The relationship between them is
where N is the data rate (bps) and r is the number of data elements carried in one signal element. The value of r in analog transmission is r = log2L, where L is the number of different signal elements.
PG:137 Data Communications and Networking By Behrouz A.Forouzan 5th Edition.

5. Data Rate Versus Signal Rate
PG:137 Data Communications and Networking By Behrouz A.Forouzan 5th Edition.

6. Data Rate Versus Signal Rate
Example 5.1: An analog signal carries 4 bits per signal element. If 1000 signal elements are sent per second, find the bit rate.
Solution: In this case, r = 4, S = 1000, and N is unknown. We can find the value of N from
PG:137 Data Communications and Networking By Behrouz A.Forouzan 5th Edition.

7. Data Rate Versus Signal Rate
Example 5.2: An analog signal has a bit rate of 8000 bps and a baud rate of 1000 baud. How many data elements are carried by each signal element? How many signal elements do we need?
Solution: In this example, S = 1000, N = 8000, and r and L are unknown. We first find the value of r and then the value of L.
PG:137 Data Communications and Networking By Behrouz A.Forouzan 5th Edition.