Question 1

The most familiar use of transmitting digital data using analog signals is the public telephone network.

Accepted Answer

The public telephone network uses analog signals to transmit digital data in the form of voice communication.

Question 2

Bandwidth efficiency measures the efficiency with which bandwidth can be used to transmit data.

Accepted Answer

Bandwidth efficiency refers to how much data can be transmitted over a given bandwidth in a given amount of time. Therefore, it measures the efficiency with which bandwidth can be used to transmit data.

Question 3

Using two different voltage levels for the two binary digits is a difficult way to transmit digital signals.

Accepted Answer

Using two different voltage levels to represent the two binary digits (0 and 1) is a common and straightforward method for transmitting digital signals, as it allows for easy differentiation between the two states.

Question 4

The modulation rate of a signal is the rate,in bits per second,that data are transmitted.

Accepted Answer

The modulation rate refers to the rate at which the signal changes, typically measured in baud, not the rate at which data is transmitted in bits per second.

Question 5

Modulation does not permit frequency division multiplexing.

Accepted Answer

Modulation enables frequency division multiplexing by allowing multiple signals of different frequencies to be combined and transmitted together over a single channel.

Question 6

The biphase codes are known as self-clocking codes.

Accepted Answer

Biphase codes are known as self-clocking codes because they use the transitions (changes in signal level) within the code to maintain synchronization. This means that the receiver can extract a clock signal from the received data without needing a separate clock signal.

Question 7

PCM starts with a continuous time,continuous amplitude signal from which a digital signal is produced.

Accepted Answer

PCM (Pulse Code Modulation) is a process of converting a continuous time, continuous amplitude signal into a digital signal by sampling the signal at regular intervals and quantizing each sample to a binary value. Therefore, the statement is true.

Question 8

Some transmission media,such as optical fiber and unguided media,will only propagate analog signals.

Accepted Answer

The answer of Some transmission media,such as optical fiber and...

Question 9

A category of encoding techniques known as multilevel binary addresses some of the deficiencies of the NRZ codes.

Accepted Answer

Multilevel binary encoding techniques, such as Manchester encoding and differential Manchester encoding, are designed to address some of the issues with NRZ codes, such as the lack of synchronization between the transmitter and receiver and the distortion caused by long strings of zeros or ones.

Question 10

The encoding scheme is the mapping from data bits to signal elements.

Accepted Answer

The encoding scheme is the mapping from data bits to signal elements or symbols. This process is essential to transmit data over a communication channel.

Question 11

In ________ signaling an analog or digital data source is encoded into a digital signal.
A)polar
B)carrier
C)analog
D)digital

Accepted Answer

In digital signaling, the data source is encoded into a digital signal. This means that the signal can only have two values (0 or 1) and does not vary continuously like in analog signaling.

Question 12

A scrambling coding technique based on bipolar-AMI and commonly used in North America is ________.
A)HDB3
B)ASK
C)MFSK
D)B8ZS

Accepted Answer

The scrambling coding technique based on bipolar-AMI and commonly used in North America is B8ZS (Binary 8 Zero Substitution). HDB3 (High Density Bipolar 3) is another scrambling technique based on bipolar-AMI but is commonly used in Europe and Asia. ASK (Amplitude Shift Keying) and MFSK (Multiple Frequency Shift Keying) are modulation techniques and not scrambling techniques.

Question 13

In ________,the two binary values are represented by two different amplitudes of the carrier frequency.Commonly,one of the amplitudes is zero.One binary digit is represented by the presence,at constant amplitude,of the carrier,the other by the absence of the carrier.
A)amplitude shift keying
B)phase shift keying
C)frequency shift keying
D)high density bipolar-3 zeros

Accepted Answer

The description given matches the technique of Amplitude Shift Keying (ASK), where two different amplitudes of the carrier frequency are used to represent two binary values. One amplitude is typically set to zero, and the presence or absence of the carrier signal at a constant amplitude represents the two binary digits. Phase shift keying (PSK) and frequency shift keying (FSK) use variations in the phase and frequency of the carrier signal, respectively, to represent binary digits. The choice D, high density bipolar-3 zeros, is not a modulation technique but a coding scheme used in digital telecommunications.

Question 14

A ________ converts digital data to analog signal so that it can be transmitted over an analog line.
A)modem
B)satellite
C)router
D)receiver

Accepted Answer

Modems are used to convert digital data into an analog signal that can be transmitted through analog communication lines, such as telephone lines. Satellites, routers, and receivers do not perform this function.

Question 15

The simplest form of digital encoding of ________ is to assign one voltage level to binary- one and another to binary-zero.
A)digital data
B)carrier data
C)AM data
D)analog data

Accepted Answer

Digital encoding is used to represent digital data, which is in the form of binary digits (0 and 1). The simplest form of digital encoding is to assign one voltage level to binary-one and another voltage level to binary-zero. This is called non-return-to-zero (NRZ) encoding. Carrier data and AM data are analog signals which cannot be directly encoded as binary digits.

Question 16

More efficient use of bandwidth can be achieved if each signaling element represents one bit.

Accepted Answer

More efficient use of bandwidth can be achieved if each signaling element represents more than one bit, as this increases the bit rate without requiring additional bandwidth.

Question 17

A digital signal is a sequence of discrete,discontinuous voltage pulses.

Accepted Answer

A digital signal is indeed a sequence of discrete, discontinuous voltage pulses that represent the binary values of 0 and 1.

Question 18

Both analog and digital information can be encoded as either analog or digital signals.

Accepted Answer

Both analog and digital information can be translated into either analog or digital signals depending upon the method used to send or store the information. For instance, analog information like voice signals can be translated into digital signals through a process called analog-to-digital conversion (ADC) for digital transmission or storage. Similarly, digital information can be translated into analog signals through a process called digital-to-analog conversion (DAC) for analog transmission or storage. Therefore, both analog and digital information can be encoded as either analog or digital signals.

Question 19

Amplitude shift keying is less susceptible to error than binary frequency shift keying.

Accepted Answer

Amplitude shift keying (ASK) is generally more susceptible to noise and interference than binary frequency shift keying (BFSK), because changes in amplitude are more likely to be affected by noise, making ASK less reliable in noisy environments compared to BFSK, which varies the frequency of the carrier signal for encoding.

Question 20

In general,the equipment for encoding digital data into a digital signal is more complex and expensive than digital to analog modulation equipment.

Accepted Answer

Digital-to-digital encoding equipment is generally simpler and less expensive than digital-to-analog modulation equipment because it deals with directly manipulating digital signals without the need for conversion to analog forms, which requires more complex and costly components to handle the nuances of analog signals.

Quiz 5: Signal Encoding Techniques