Deck 9: Wired Digital Communications

Question 1

A term used to indicate that only a portion of the data bandwidth of a T1 line is being used is:

A) Companded T1
B) Multiplexed T1
C) Fractional T1
D) T1/2

Answer 1

C

Question 2

The T1 data rate is:

A) 512 kbps
B) 56 kbps
C) 1.544 Mbps
D) 44.736 Mbps

Answer 2

C

Question 3

In what type of transmission is bit rate and baud rate the same?

A) hexadecimal transmission
B) binary transmission
C) analog
D) pulse amplitude modulation

Answer 3

B

Question 4

The point where the communications carrier brings in service to a facility is called the:

A) point of presence
B) patch line
C) CSU/DSU
D) termination line

Question 5

Which is not an advantage of digital data communication systems over analog communications?

A) They eliminate errors in the received signal
B) They have narrower bandwidths
C) They have superior noise performance
D) They have the ability to process the signal at the transmitter and receiver using digital signal processing techniques

Question 6

The most desired pulse modulation scheme is:

A) pulse position modulation (PPM).
B) pulse width modulation (PWM).
C) pulse frequency modulation (PFM).
D) pulse amplitude modulation (PAM).

Question 7

A two-tone amplitude modulation system uses 400 Hz for a "one" and 550 Hz for a "zero" and a carrier frequency of 9.35 MHz. The required bandwidth for this communication channel is:

A) 400 Hz.
B) 1100 Hz
C) 550 Hz
D) 950 Hz
E) 800 Hz

Question 8

A certain language has 18 letters in its alphabet. How many bits are required to represent the 18 letters?

A) 5
B) 6.1
C) 4.2
D) 3.8

Question 9

Another name for delta modulation is

A) pulse modulation
B) codec
C) slope modulation
D) all of the above

Question 10

A digital transmission has an error probability of 1 x 10^-5 and is 1 x 10^8 bits long. Its BER is:

A) 1 x 10^-3
B) 1 x 10^-8
C) 1 x 10^-5
D) 1 x 10^-4

Question 11

The major advantage of a delta modulator over PCM circuitry is its

A) greater resistance to any error produced by noise
B) bandwidth characteristics
C) frequency response of the intelligence signal
D) simplicity in design

Question 12

A cell relay technique designed for voice, data and video traffic and considered to be an evolution of packet switching is:

A) POP
B) ATM
C) ACR-3
D) MPEG-2

Question 13

An example of a packet switching network designed to carry data traffic over a public data network is:

A) IEEE 802.5
B) frame relay
C) IEEE 802.3
D) none of the above

Question 14

Which of the following is not a major protocol function?

A) character insertion
B) line control
C) flow control
D) framing

Question 15

An advantage of PPM over PWM is

A) its frequency response of the intelligence signal
B) its greater resistance to any error produced by noise
C) its simplicity in design
D) its limited bandwidth

Question 16

What is the coding efficiency if a language has 18 letters in its alphabet?

A) 95%
B) 87%
C) 83%
D) none of the above

Question 17

A technique used to transport data from multiple users over the same data channel is:

A) Fractional T1
B) FDMA
C) TDMA
D) CDMA

Question 18

Which of the following can be used to generate PWM?

A) PTM
B) PAM
C) PCM
D) PPM

Question 19

Baseband analog data channels are characterized by:

A) the fact that a coder has converted the digital intelligence into a specific coding format for subsequent transmission.
B) the fact that a modem has converted the intelligence to an analog signal for use on an analog channel
C) the fact that the intelligence is being transmitted at its base frequencies; no modulation to another frequency range has occurred.
D) the fact that a modulator has converted the analog intelligence into a modulated analog signal on another frequency range