Question 1

In Non Return to Zero encoding schemes,the signal or voltage level does not return to 0v (zero volts).One of the problems with this type of encoding is that

Accepted Answer

One of the main challenges with Non Return to Zero encoding is synchronizing the timing of the transmitter and receiver. This is because the signal or voltage level does not return to 0v, which can make it difficult to accurately determine when a signal starts and ends. As a result, the timing of the transmitter and receiver must be precisely synchronized in order to ensure reliable communication.

Question 2

In modern communication systems,data is sent from one point to another via

Accepted Answer

In modern communication systems, data is primarily transmitted using electromagnetic signals. This can include radio waves, microwaves, or other forms of electromagnetic radiation. These signals are typically modulated to carry the data and then demodulated to extract the information at the receiving end.

Question 3

An encoding scheme is used

Accepted Answer

D

Question 4

Asynchronous transmission includes a start and stop bit with each character transmitted to ensure

Accepted Answer

The start and stop bits in asynchronous transmission are used to signal the beginning and end of a character, which helps the receiver maintain synchronization with the sender. This is particularly important because there is no continuous stream of data in asynchronous transmission, unlike synchronous transmission. Option A, B and E are incorrect because the start and stop bits are not related to the total number of bits, continuity of data, or variable length encoding schemes. Option C is partially correct because start and stop bits do detect errors in transmission, but their main purpose is synchronization.

Question 5

Analog encoding of digital information modulates a wave known as the
carrier in terms of its phase,frequency or amplitude.

Accepted Answer

This statement is true. Analog encoding of digital information can be achieved by modulating a carrier wave in terms of its phase, frequency or amplitude.

Question 6

Standards are important when devices must communicate together.The four characteristics governed by these standards are

Accepted Answer

The four characteristics governed by communication standards are mechanical, electrical, functional, and procedural, which ensure proper interaction and interoperability between devices.

Question 7

One of the main differences between amplifiers and repeaters is that

Accepted Answer

Amplifiers boost both the signal and any noise present, while repeaters regenerate the signal to reduce noise.

Question 8

Except for digital cellular telephones,copper wire is required for digital transmission.

Accepted Answer

Copper wire is not the only medium for digital transmission. Other mediums include fiber optic cables, coaxial cables, and wireless transmissions.

Question 9

Synchronous serial transmissions are frame based,require the use of a preamble and are more efficient than asynchronous serial transmissions.

Accepted Answer

Synchronous serial transmissions are designed to transmit continuous streams of data without the need for start and stop bits, which makes them more efficient than asynchronous serial transmissions. They are also frame-based and require the use of a preamble to synchronize the transmitter and receiver. Therefore, the statement is true.

Question 10

It is difficult to use low frequencies for unguided radio transmission of data because the antenna dishes would have to be extremely large.

Accepted Answer

Low frequencies have long wavelengths which require larger antenna dishes for efficient transmission. This makes it impractical for unguided radio transmission of data.

Question 11

A carrier wave is modulated with 4 amplitudes and 4 phase changes.How many bits can be represented with each signal change?

Accepted Answer

Each signal change can represent 4 amplitudes and 4 phase changes, which is 4 x 4 = 16 combinations. 16 combinations can be represented by 4 bits (since 2^4 = 16).

Question 12

For amplitude,frequency or phase shift keying,that respective characteristic of the carrier wave is changed to indicate the next binary digit.These binary digits can be represented by this signal change or a lack of signal change.

Accepted Answer

This statement is true, as each type of keying (amplitude, frequency, and phase shift) changes a specific characteristic of the carrier wave in order to represent binary digits. This signal change (or lack thereof) can then be detected by a receiver to interpret the transmitted information.

Question 13

Analog signals are

Accepted Answer

Analog signals are continuous signals that can take any value within a specific range, while digital signals are discrete signals that can only take specific values at specific times.

Question 14

The efficiency of an asynchronous transmission using 1 stop bit,1 start bit and 1 parity bit is

Accepted Answer

In asynchronous transmission, each character is framed with a start bit, a stop bit, and a parity bit. This means for every 8 data bits, there are 3 additional bits (1 start, 1 stop, 1 parity), making a total of 11 bits. The efficiency is calculated as the ratio of data bits to total bits: 8/11 ≈ 0.727 or 72.7%, which is closest to 70%.

Question 15

A carrier wave is modulated with 4 amplitudes and 4 phase changes.How many possible signal combinations are there?

Accepted Answer

To calculate the possible signal combinations, we multiply the number of amplitudes by the number of phase changes: 
4 amplitudes x 4 phase changes = 16 possible signal combinations. Therefore, the correct answer is C) 16.

Question 16

Analog signals are less susceptible to noise interference and are more prone to attenuation than digital signals

Accepted Answer

Digital signals are less susceptible to noise interference compared to analog signals, but analog signals are indeed more prone to attenuation over long distances.

Question 17

Digital signals are

Accepted Answer

Digital signals are quantized or discrete in nature, meaning they take on only distinct values at specific intervals of time. Continuous signals take on all values at any given time, while discontinuous signals have interruptions or gaps in their values. Therefore, option B is the correct choice.

Question 18

Identify each of the following as either analog or digital signals.Use A if analog and D if digital.
Whales
Human voice
Computer bus communication
Cellular telephones
Satellite transmission
T-1 circuits

Accepted Answer

The answer of Identify each of the following as either...

Question 19

In order to compensate for synchronization problems,another type of encoding method called biphase can be employed.These methods place a clock pulse within the data stream.

Accepted Answer

Biphase encoding methods do indeed place a clock pulse within the data stream to help compensate for synchronization problems.

Question 20

Each signal change or element is called a

Accepted Answer

A baud is a unit of signaling speed that represents the number of signal changes or elements transmitted per second.

Quiz 16: Data Communication Fundamentals

In Non Return to Zero encoding schemes,the signal or voltage level does not return to 0v (zero volts) .One of the problems with this type of encoding is that