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ASCII
Name: _______________________________
HOMEWORK 1 – BINARY CALCULATIONS (13 PTS MAX)
1. Use the ASCII code to indicate the 7-bit code representation for the
following: .5 pts each
A. N _ _ _ _ _ _ _
B. v _ _ _ _ _ _ _
C. ! _ _ _ _ _ _ _
2. Now, add odd parity to each of the codes in problem 1A and 1B above,
placing the parity bit in the most significant digit. Add even parity to
codes in problem 1C, placing the parity bit in the most significant digit. .5
pts each
A. N _ _ _ _ _ _ _ _
B. v _ _ _ _ _ _ _ _
C. !
________
3. What are the capabilities of even single bit parity? .5 pts each
A. It can detect the presence of errors when there are how many
errors present?
B. It can correct how many errors?
C. How are these capabilities different for odd parity?
4. Determine the decimal equivalent value for each of the following binary
numbers .5 pts each
A. 10010011
B. 01101010
C. 10001100
5. Determine the binary representation for each of the following decimal
numbers. .5 pts each
A. 172
B. 131
C. 89
6. How many bits are needed to uniquely represent a code that contains:
.5 pts each
A. 720 different symbols
B. 423 different symbols
C. 99 different symbols
7. The iPhone 7 Plus has the potential to provide an uncompressed video
stream output with a per frame resolution of 3840 x 2160 pixels (4K). The
camera has a max rate of 60 fps. The camera also has a capability of
depicting 1.6 billion different colors for each pixel. 1 pt each
A. How many bits are required to represent each pixel?
B. What is the minimum bit rate required to satisfactorily transmit this
camera’s uncompressed bit stream?
C. How much data storage is required to store in bytes 3 minutes of
uncompressed video?
Assignment 1 – 9/2016
8. An 8 x8 data matrix has been received as shown below. The parallel
parity bits are shown, assuming EVEN parity. Determine if any errors are
present, and IF POSSIBLE, correct them., 1 pt
1 0 1 1 0 1 0 0
0
0 1 0 1 1 1 1 0
1
1 0 0 0 0 1 1 0
1
0 0 0 0 1 0 1 0
1
1 0 1 0 1 0 1 0
0
0 1 1 0 0 0 1 0
1
1 0 1 0 0 1 1 1
1
0 0 0 1 1 0 0 1
1
0 0 0 1 0 0 1 0
Assignment 1 – 9/2016
Basic Terminology and
Information
Lesson Objectives
By the end of this lesson, you will be able to:
• Define the elements of a communications system
• Identify and define the characteristics of analog and
digital information representations
• Define decibel and describe its use in transmission
• Define parity and apply parity schemes
• Define bit, byte, and baud, and calculate the number of
bits and bytes present
• Describe audio, data, image, and video information
• Describe the purpose and effect of a filter
• Describe raster and vector images
• Describe the characteristics of common coding
schemes: JPEG, GIF, PNG, BMP
• Define response time
Communications Trends
• Traffic increasing constantly
• Traffic type is changing – from voice to data
• Range of services constantly expanding –
sophistication, complexity, variety
• Technology changes:
– Faster, cheaper computing & communication
capabilities
– Network capabilities greater, more varied
– Internet acceptance and world dependence
– Mobility
Communications
Three essential elements of any communications system:
2. Receiving end
1. Transmitting end
Terminal
Interface
3. Connecting medium
Interface
Two additional criteria for effective communications:
1. Message must be understandable at the receiving end
2. Message received = message sent
error control
Terminal
Information
Information – facts, numbers, statistics, etc. that can be
processed or transmitted. It is usually represented by
alphabet or other types of symbols.
Information
Analog
Digital
•Audio
•Data
•Image
•Video
1 Cycle
Amplitude
0
Amplitude
Frequency
Cycles per second = Hertz (Hz)
Phase – the relative position of a wave at a given
moment in time.
T1
Phase Difference
T1 T2
Phase Shift
Information can be represented in an analog signal by:
Amplitude, Frequency, and/or Phase
Digital Information
bit
Amplitude
0
Amplitude
bit
Digital information is represented by a discrete pattern.
Please note that digital information could be 0 or 1.
In this diagram, digital information is either 1 or -1
Digital Information Cont’d
Frequency
• Digital – typically 2 states; varies instantaneously between 2
electrical values
• Information is typically conveyed by the state, NOT by the frequency
• Digital analogy is bps = bits per second
• Limited information can be represented by only 2 states
1 bit = 2 possible states
5 bits =
2 bits =
6 bits =
3 bits =
7 bits =
4 bits =
8 bits =
8 bits = 1 BYTE (B)
Analog vs. Digital
• Digital information:
– Can be separated from noise
– Always contains noise.
– Each successive generation of recording, transmission
decreases quality
Decibels
• dB = relative measure of signal loss or gain. Measures
the logarithmic loss or gain.
• dB = 10 log10 (P2/P1)
P1 = 10 watts
dB = 10 log10 (5/10)
= 10 log10 (.5)
= 10 (-0.3)
= -3
= a “3 dB loss”
P2 = 5 watts
Abbreviated Notations
Kilo = 1,000 = 103 (210)
Mega = 1,000,000 = 106 (220)
Giga = 1,000,000,000 = 109 (230)
Tera = 1,000 giga = 1012 (240)
Peta = 1,000 tera = 1015 (250)
Exa = 1,000 peta = 1018 (260)
Zetta = 1,000 exa = 1021 (270)
Yotta = 1,000 zetta = 1024 (280)
B≠b
Binary Number System
Decimal Number System:
43,219
4
3
2
1
9
10,000 1,000
100
10
1
103
102
101
100
104
Binary Number System:
10100111
1
0
1
27
26
25
128
64
32
0
0
1
1
1
24
23
22
21
20
16
8
4
2
1
Assigning Binary Numbers to Groups
Assigning Binary Numbers to Groups
How many bits do I need to assign a unique
binary code to a group of 16 symbols?
1.
2.
Given that the group has n = 16 symbols.
What does n equal in binary? How many bit positions (binary
ASCII

American Standard Code for Information Interchange
26 UPPER CASE letters
26 lower case letters
10 numbers
At least 33 symbols: [email protected]#\$%&*, etc.
Utilizes the concept of multiple bits to represent each
character or symbol
• Minimum number of bits required to represent this full set
= ??
Single Bit Parity
• A single bit used to help detect the presence of errors
caused by transmission
• Two types of parity
– Odd parity
– Even parity
• Parity bit combined with the ASCII representation = 1
byte
• Limitations to Parity error detection
• Single bit errors comprise 50 – 60% of error cases
• Used in PC buses: SCSI, PCI
How to Determine the Parity Bit
1.
2.
3.
4.
5.
Does the system utilize even parity or odd parity?
For even parity, the total number of ones MUST be
EVEN
For odd parity, the total number of ones MUST be
ODD
Count the number of ones in the data bit positions
Assign the parity bit to make the total number of ones
even for EVEN parity; or odd for ODD parity.
Using the Parity Bit to Detect Errors
1.
2.
3.
4.
Does the system utilize even parity or odd parity?
Count the total number of ones in the data segment
(usually a Byte)
If the system is using EVEN parity, the total number of
ones MUST be even. If the total is odd → ERROR
If the system is using ODD parity, the total number of
ones MUST be odd. If the total is even → ERROR
Where is the error? How many errors are there?
When can parity detect the presence of errors?
Parallel Parity
1
1
0
1
1
0
1
0
1
0
0
1
1
0
0
1
1
0
1
0
0
1
1
0
1
1
1
0
0
0
1
1
0
1
1
0
1
0
0
0
1
0
1
1
0
1
0
0
0
0
1
1
0
1
1
1
0
0
0
1
1
0
0
1
1
0
0
1
1
1
0
1
0
1
1
0
1
1
0
0
• Detects and corrects single bit errors
• Can possibly detect the presence of multiple errors, but no correction
Parallel Parity Example
1
1
0
1
1
0
1
0
1
0
0
1
1
0
0
1
1
0
1
0
0
1
1
0
1
1
1
1
0
0
1
1
0
1
1
0
1
0
0
0
1
0
1
1
0
1
0
0
0
0
1
1
0
1
1
1
0
0
0
1
1
0
0
1
1
0
0
1
1
1
0
1
0
1
1
0
1
1
0
0
1
1
0
1
1
0
1
0
1
0
0
1
1
0
0
1
1
0
1
0
0
1
1
0
1
1
1
1
0
0
1
1
0
0
1
0
1
0
0
0
1
0
1
1
0
1
0
0
0
0
1
1
0
1
1
1
0
0
0
1
1
0
0
1
1
0
0
1
1
1
0
1
0
1
1
0
1
1
0
0
Baud
• Often confused with bits and bit rate

• Baud = a measure of the number of signals sent
• Does NOT measure the amount of information sent
• Typically associated with analog signals
1 baud
1 baud
1 baud
Audio Information

Analog → it can be described by amplitude and frequency
Each frequency has a unique and consistent sound
Most common audio = voice
Typical voice range of frequencies: 100 – 10,000 Hz
Combinations of these frequencies gives everyone a distinctive
sound
• Typical human hearing range: 20 – 20,000 Hz
Transmitting the Voice
• System Requirement to transmit speech –
• Two competing rules:
– As we send more frequencies, sound improves
– The more we send, the greater the cost
• Goal – a compromise
• Research result: a subset of the frequencies – the dominant
frequencies – are necessity to distinguish voice transmission
– Speech is understandable
– Voice is recognized
– Additional frequencies do not measurably improve either characteristic
Voice Transmission 2
• Telephone system focuses on core frequencies
10
0
300
100
1000
500
3400
3000
10,000
4000
Frequency Range

Bandwidth – range of frequencies, equal to the difference between
the highest and lowest frequencies in the range under consideration
Voice Transmission 3
• Other communications systems have demands beyond those of
telecom systems; understanding and recognizing spoken word is not
– Richer, more accurate sounds
– Requires more frequencies → greater bandwidth
– Greater bandwidth → greater cost
• High fidelity system: bandwidth approximately 15,000 Hz
• CD system has even greater bandwidth: approximately 20,000 Hz
• DVD audio system is even greater: theoretical bandwidth limit
approaches 95,000 Hz.
Amplitude
Filters
4 kHz
8
12
Theoretical
16
Frequency
Actual
Digital Audio
Complex audio is stored in digital format; requires tremendous
quantity of bits.
CD “samples” audio 44,100 times per second
Stereo requires 2 separate channels
44,100 x 2 = 88,200 samples/second
Each sample is represented by 16 bits
88,200 samples x 16 bits = 1,411,200 bits/second
CD stores 74 minutes of music
74 minutes = 60 seconds/min x 74 minutes = 4,440 seconds
1,411,200 bps x 4,440 seconds = 6,265,728,000 bits
DVD capacity is at least 37.6 Gb (single sided, single layer)
CDs
0.6 microns*
1.6 microns*
*1 micron = 1 millionth meter
= 10-6 meters
Label
Aluminum 125 nm
Protective acrylic
1.2 mm
0.11 μm
.83 – 3.5 μm
Polycarbonate plastic
Pit
4.8” in diameter
Total track = 3.5 miles
DVDs
.3 μm
.740 μm
Aluminum 120 nm
Protective acrylic
Label
1.2 mm
0.16 μm
.4–2 μm
Polycarbonate plastic
4.8” in diameter
Total track = 7.5 miles
CDs vs DVDs vs Blu-Rays
Data
• Data – information that can be represented by a finite alphabet or
set of symbols.
• Data is typically digital in nature
• Most common representation is ASCII
• ASCII is simple, but requires a lot of bits to communicate a
meaningful message
Image
• Image information – pictures, charts, graphs, medical images, CAD
drawings, etc.
• NOT individual characters
ASCII
Images are represented as:
•Vector images
•Raster images
Vector vs. Raster Images
Vector Images
• Collection of straight and curved line segments
• Stored/represented by their mathematical or geometric equation
• Images primarily originate from software. Cannot scan an image file
and save it as a vector file.
• Enables exact, precise reproduction repeatedly
• Scalable – increases/decreases in size of vector image does NOT
affect clarity. Lines remain crisp and sharp.
• Fonts are a vector object
• Primary disadvantage – unsuitable for producing photo quality
images. Usually consist of solid areas of color; cannot depict
continuous subtle tones of a photo
• Most common application – ??
Raster Images
• Two-dimensional arrays of spots
• Each spot = pixel.
• Pixel = smallest element of a display space that can be
independently assigned color and intensity
• Functions based upon a human processing capability: Divide a still
image into a collection of small dots and we will automatically
reassemble the dots into a meaningful image
• Simplest form: black or white
A Simple Raster Image
Set 0 = white and 1 = black
0111110
0100000
0100000
0100000
0111000
0000100
0000010
0000010
0000010
0000100
0111000
Benefit to this scheme = minimal bits required: 1/pixel
Disadvantage = severe limitations to black and white only
Enhancing Raster Images

Expand the number of possible appearances for each pixel beyond black
Gray scale
Quantity of possible shades is limited by the number of bits assigned to
each pixel
– 1 bit – 2 shades
– 2 bits – 4 shades
– 3 bits – ?

Next level of possibilities – different colors instead of different shades of
gray
– Requires more bits/pixel
– Assign additional information to each pixel to represent colors
– Common scheme is RGB. Represent value for each of three fundamental colors
by a value which is then stored for each pixel

Many different coding schemes exist today
JPEG

Joint Photographic Experts Group
Most widely used digital image format
Best for large still photographs, where file size is most important
Photos are stored in raster format
JPEG utilizes compression
Some information is lost in the process. The result:
– Not visible by our eyes for photos
– Poor for images with sharp edges (e.g., letters, line art)
• Not good for small images, images with text, images that will be
edited repeatedly
• 24 bits/pixel = 16,777,216 color possibilities
• Compressed file is only about 5% of the original file
GIF

Graphic Interchange Format
Utilizes 8 bits to describe color → 256 possible colors
Less precise, lower quality than JPEG
Well suited for non-photo applications, such as line art, logos, icons
Utilizes Lempel Zev Welch (LZW) compression scheme
Supports animation and transparent backgrounds
Ongoing issue of royalties with compression scheme authors
PNG
• Portable Network Graphics
• Developed with two primary goals:
– Escape from the royalty battle associated with GIF
– Improve by overcoming limitations of GIF and JPEG

48 bits/pixel provides tremendous power
Compresses to 10 – 30% smaller than GIF
Has a patent-free compression algorithm
Finally becoming an accepted graphics standard
New generation of browsers should support PNG
BMP

Bit Map File format
Least sophisticated raster format
Native to Windows
Utilizes up to 24 bits/pixel
Compression technique is simple, effective, but not necessarily
efficient
• Best applications – line drawings, simple color images
Comparing Formats
225 DPI Picture
72 DPI Picture
BMP
3.47 Mb
364 kb
PNG
1.84 Mb
209 kb
GIF
685 kb
77.7 kb
JPEG (high
Quality)
163 kb
42 kb
JPEG (low
Quality)
69.5 kb
25.4 kb
Video Information
• Video = series of raster images
• Television screen is a series of pixels arranged in lines
across screen
• Each pixel has a specific degree of illumination to
create the picture
• Effectiveness depends on two capabilities of our
perception:
– Divide a still image into a collection of small dots and we
will automatically reassemble the dots into a meaningful
image
– Divide a moving scene into sequence of still pictures
(images), show them in rapid succession, and we will
translate them into a single moving scene
B & W Video
“Screen”
“Ray” of electrons
Cathode (-)
Anode (+)
Phosphor coating
Phosphor – emits visible light when
exposed to a ray of electrons or
ultraviolet light
B & W TV Image
•525 lines; 480 visible
•Total pixels = 210,000
•Each line is “painted” 30 times/second
•Paints a total of 15,750 lines/second
•Standard TVs use interlacing
•Most monitors use progressive scanning
•Transmitted signal tells TV how to
illuminate each pixel
•.5 volts = black
•2 volts = white
•National Television Standards Committee (NTSC) = analog TV
Color TV

Essentially three of the same configuration as B & W superimposed
One electron beam each for red, green, blue
One phosphor sheet for each of these beams
HDTV

Digital signal replaces the analog signal
1,080 lines of resolution instead of 525
1,920 pixels per line instead of 500
1080p = 1920 x 1080 pixels with progressive scanning
Scanning at 60 scans/second = 124,416,000 pixel images/second
Difference = better resolution
Natural Volume of data > 1 Gbps
MPEG-2 is the industry standard; reduces the volume of data by 55
to 1
• Resultant signal can still fit into the same 6 MHz bandwidth as
analog TV
4k

Digital signal replaces the analog signal
2,160 lines of resolution instead of 1080
3,840 pixels per line instead of 1,920
4k= 3,840 x 2,160 pixels with progressive scanning
Scanning at 60 scans/second = 497,664,000 pixel images/second
Difference = even better resolution than 1080p
Natural Volume of data > 4 Gbps
Response Time
• The time it takes for a system to react to a given input
• Response time challenge is analogous to our speech transmission
challenge
• People want minimal response time
• The shorter the response time, the greater the cost
• Human tolerance continually decreases as system capabilities
increase
• Impacts on Response time:
– Quantity of data
– Type of transmission system
What We’ve Covered
• Define the elements of a communications system
• Identify and define the characteristics of analog and
digital information representations
• Define decibel and describe its use in transmission
• Define parity and apply parity schemes
• Define bit, byte, and baud, and calculate the number of
bits and bytes present
• Describe audio, data, image, and video information
• Describe the purpose and effect of a filter
• Describe raster and vector images
• Describe the characteristics of common coding
schemes: JPEG, GIF, PNG, BMP
• Define response time
Homework