Question No 1
Write down three characteristics of a Sine Wave.
Answer:
- Amplitude
- Frequency (or Period)
- Phase
Question No 2
A sine wave has a frequency of 6 Hz. What is its period?
Answer:
Formula:
T = 1 / f
Given:
f = 6 Hz
T = 1 / 6
T = 0.17 seconds
Question No 3
How does noise affect FSK?
Answer:
Noise usually lasts longer than the duration of one bit.
Because of this, when noise affects the signal, it can affect multiple bits at the same time, which may cause errors in data transmission.
Question No 4
What is simplex mode of transmission?
Answer:
Simplex transmission is one-way communication.
Only one device can send data, and the other device can only receive data.
Example: TV broadcasting.
Question No 5
How many components are in a data communication system?
Answer:
There are five components:
- Message
- Sender
- Receiver
- Transmission Medium
- Protocol (set of rules)
Question No 6
What is the purpose of distributed processing?
Answer:
Distributed processing allows multiple computers to work together on a problem.
This helps solve problems faster than a single computer working alone.
Question No 7
Give methods of Analog to Analog conversion.
Answer:
Analog-to-Analog conversion is the representation of analog information using an analog signal.
Common methods include:
- Amplitude Modulation (AM)
- Frequency Modulation (FM)
- Phase Modulation (PM)
Question No 8
How many types of Bipolar encoding schemes exist?
Answer:
Bipolar encoding uses three voltage levels.
Three types are:
- AMI (Alternate Mark Inversion)
- B8ZS
- HDB3
Question No 9
Define Sampling Rate.
Answer:
Sampling rate is the number of samples taken from an analog signal per second to convert it into digital form.
Higher sampling rate gives more accurate digital reproduction
Question No 10
How is the bandwidth of a modem measured?
Answer:
The bandwidth of a modem is measured in bits per second (bps), not bytes.
Question No 11
What is frequency spectrum?
Answer:
Frequency spectrum is the collection of all frequency components contained in a signal.
Question No 12
What is a digital signal? Give an example.
Answer:
A digital signal is a discrete signal that has limited values, usually 0 and 1.
Example:
Computer data represented in binary form (0 and 1).
Question No 13
Give similarities between 4-QAM and 8-QAM.
Answer:
Both modulation techniques use amplitude and phase changes to represent data.
In both cases, phase shifts are used along with amplitude variations.
Question No 14
What is HDB3?
Answer:
HDB3 is a modified version of AMI encoding used in Europe and Japan.
It replaces four consecutive zeros with special patterns to maintain synchronization.
Question No 15
Define Bit Interval and Bit Rate.
Answer:
Bit Interval:
The time required to transmit one single bit.
Bit Rate:
The number of bits transmitted per second (bps).