3.3 - Digital Transmission of Digital Data

Question 1

All computer systems produce _____________

Answer 1

binary data

Question 2

The _____________ is the language that computers use to represent data

Answer 2

coding scheme

Question 3

A ___________ is a symbol that has a common, constant meaning

Answer 3

character

Question 4

Characters in _______ ____________, as in computer systems, are represented by groups of bits that are binary zeros (0) and ones (1)

Answer 4

data communications

Question 5

The groups of bits representing the set of characters that are the “alphabet” of any given system are called a ______ _______, or simply a code

Answer 5

coding scheme

Question 6

A ______ is a group of consecutive bits that is treated as a unit or character

Answer 6

byte

Question 7

One (1) byte is normally composed of ___ bits and usually represents one character

Answer 7

8

Question 8

Three predominant coding schemes in use today:

Answer 8

1. American Standard Code for Information Interchange (ASCII)
2. ISO 8859
3. Unicode

Question 9

The most popular code for data communications and is the standard code on most microcomputers

Answer 9

ASCII

Question 10

There are two types of ASCII:

Answer 10

1. 7-Bit Code ASCII
2. 8-Bit Code ASCII

Question 11

Has 128 valid characters (2^7 = 128)

Answer 11

7-Bit Code ASCII

Question 12

Has 256 characters (2^8 = 256)

Answer 12

8-Bit Code ASCII

Question 13

Standardized by the International Standards Organization

Answer 13

ISO 8859

Question 14

An 8-bit code that includes the ASCII codes plus non-English letters used by many European languages (e.g., letters with accents)

Answer 14

ISO 8859

Question 15

_____________ often uses ISO 8859

Answer 15

HTML or Hypertext Markup Language

Question 15

An information technology (IT) standard for the consistent encoding, representation, and handling of text expressed in most of the world’s writing systems

Answer 15

Unicode

Question 16

Unicode versions:

Answer 16

1. UTF-8 (8-Bit Version)
2. UTF-16 (16-Bit Version)

Question 17

Similar to ASCII

Answer 17

UTF-8

Question 18

Uses 2 bytes (called a “word”); used by Windows; beyond English or Latin characters, has Cyrillic or Chinese

Answer 18

UTF-16

Question 19

The way the internal transfer of binary data takes place inside a computer; data element is transferred simultaneously

Answer 19

Parallel transmission

Question 20

If the internal structure of the computer is 8 bit, then all 8 bits of the data element are transferred between main memory and the central processing unit simultaneously on 8 separate connections

Answer 20

Parallel transmission

Question 21

A stream of data is sent over a communication circuit sequentially in a bit-by-bit fashion

Answer 21

Serial transmission

Question 22

There is only one physical wire inside the bundle, and all data must be transmitted over that one physical wire

Answer 22

Serial transmission

Question 23

It takes n iterations or cycles to transmit n bits — thus, it is considerably slower than parallel transmission

Answer 23

Serial transmission

Question 24

The transmission of binary electrical or light pulses in that it only has two possible states, a 1 or a 0

Answer 24

Digital transmission

Question 25

The most commonly encountered voltage levels range from a low of +3/-3 to a high of +24/-24 volts

Answer 25

Digital transmission

Question 26

All digital transmission techniques require:

Answer 26

1. A set of symbols 2. The symbol rate

Question 27

1. Unipolar Signaling 2. Bipolar Signaling

Answer 27

Digital Transmission Techniques

Question 28

Voltage is always positive or negative (single polarity, like in DC current)

Answer 28

Unipolar Signaling

Question 29

A 0 volts (no current) is used to transmit a 0 and a signal of +5v is used to transmit a 1

Answer 29

Unipolar Signaling

Question 30

The ones and zeros vary from a pulse voltage to a minus voltage (like an AC current)

Answer 30

Bipolar Signaling

Question 31

A bipolar technique where the voltage alternates from +5 volts (a symbol indicating a 1) to -5 volts (a symbol indicating a 0) without ever returning to 0 volts

Answer 31

Nonreturn to zero (NRZ)

Question 32

Another bipolar technique where it always returns to 0 volts after each bit before going to +5 volts (the symbol for a 1) or -5 volts (the symbol for a 0) --- half of every bit pulse starts with zero

Answer 32

Return to zero (RZ)

Question 33

A third bipolar technique where a 0 is always sent using 0 volts, but 1s alternate between +5 volts and -5 volts

Answer 33

Alternate mark inversion (AMI)

Question 34

AMI is used on ____ and ____ circuits

Answer 34

T1...T3

Question 35

The signaling used in Ethernet

Answer 35

Manchester

Question 36

A special type of bipolar signaling in which the signal is changed from high to low or from low to high in the middle of the signal

Answer 36

Manchester

Question 37

In Europe, bipolar signaling is sometimes called _____________ signaling because you are moving between a positive and negative voltage potential

Answer 37

double current

Question 38

In general, ___________ signaling experiences fewer errors than __________ signaling because the symbols are more distinct

Answer 38

bipolar...unipolar

Question 39

Changing the ___________ of a current (from positive to negative, or vice versa) is more difficult than changing its magnitude

Answer 39

polarity