## Quiz 8 :

Data and Network Communication Technology

Answer:

Serial Transmission

Serial transmission sends bits one at a time over a single transmission line or electrical circuit.

Explanation:

Serial transmission implements a single transmission line. The data bits are transmitted sequentially through the line and the recipient re-assembles these bits to larger units, such as bytes. LAN is an example of serial transmission.

Answer:

Effective Data Transfer Rate Calculation

The block check character (BCC) adds one byte of data to each 48 bytes of raw data to be transmitted as a block. The details provided in the problem are given below:

Therefore,

The problem also states that

Therefore, for 1000 blocks

Since the problem states an average error rate of 1 per thousand, the number of transmissions becomes 1001. Therefore,

Therefore, the efficiency of the transmission is given as

The raw data rate is given as 10 Mbps. So the effective data transfer rate of the given problem is calculated below:

Therefore, the effective data transfer rate of the given transmission is

.

Answer:

Signal-to-Noise Ratio Calculation

The Signal-to-Noise ratio (S/N ratio) is the relationship between a signal's power and the noise power. The relationship is given as

Here, signal power is given as

And the noise power is given as

Therefore, the signal power can be calculated as

For a 50 meter long channel,

The S/N ratio of the channel is calculated as given below:

Therefore, the Signal-to-Noise ratio for a 50 meter channel is

.

For a 1 kilometer (1000 meters) long channel,

0

The S/N ratio of the channel is calculated as given below:

1

Therefore, the Signal-to-Noise ratio for a 1 kilometer channel is

2

.

What is the maximum channel length if the receiving device requires at least 20 dB of S/N ratio for reliable operation

Let the length of the channel be a variable X.

For a x meter long channel,

3

4

The S/N ratio of the channel is calculated as given below:

5

Now, the minimum S/N ratio for the receiver is given as 20 dB. Therefore, to calculate the distance X, we evaluate the above relation with the given S/N ratio. This is given as,

6

Now evaluating X as,

7

Therefore,

8

Therefore, the maximum channel length for reliable operation is

9

.