Principles of Engineering in Communications Engineering Concepts.

Principles of Engineering in

CommunicationsEngineering Concepts

Communications History of Communications 1450 Johannes Gutenberg builds the movable

printing press. 1826 Joseph Niepce of produces the wrold’s

first permanent photographic image. 1876-Alexander Graham Bell introduced

telephone. 1877 Thomas Edison patents the phonograph. 1891 Thomas Edison and William Dickson

invent the kinetoscope. 1895 Guglielmo Marconi develops the wireless

telegraph 1925 John Logie Baird transmits the first

television signal. 1954 The transister radio or tubeless radios

become available in the USA 1990 The world wide web is created in Europe.

It’s chief architect is Tim Berners-Lee.

Communications

Assignment 1: Have students pick one form of

communication technology and develop a PowerPoint presentation to be presented to the class (See Communication Systems PowerPoint Project)

Assignment 2: Fill in the Principles of Engineering in

Communications vocabulary sheet as we go through this unit. Use the PowerPoint, textbook, and any other resources to complete the worksheet.

Communications

Communication is the ability to send and receive messages.

People to people People to machine Machine to people Machine to machine

Communications

Messages are intended to: Inform – news papers, TV news casts Educate – texts, video, DVD’s, internet. Persuade - advertising Control – machines and tools such as

Computer Numeric Control: A type of programmable control system, directed by mathematical data, which uses microcomputers to carry out various machining operations; such as a mill or lathe.

Communications

All Communications include a message, a sender, a communication channel, and a receiver.

A communication channel is the path over which a message must travel to get from the sender to the receiver.

Communications

Communications

The telegraph by Samuel Morse. Sent electronic signals using wires. Morse devised a language with a

series of long and short signals that represented letters and numbers.

Video: Telegraph Machine

http://www.youtube.com/watch?v=3tDX85ZK14Q

Communications Morse code Assignment 3:

Using an old set of walkie talkies, send a classmate a message using Morse Code.

Communications

Video: Digital vs. Analog

http://www.youtube.com/watch?v=kR7227_ndqQ

Communications Electronics Components in

Communication Transmission systems…

Copper Wire: Many older phones consist of two thin insulated copper wires twisted around each other.

Coaxial Cable: Carry many more messages all at once than twisted-pair wire. Consists of an outer tube made of a material that conducts electricity (usually copper). Inside the tube is an insulated central conductor (also copper). Several of these cables are combined into one bundle.

Communications

Optical Fibers: thin fibers of pure glass that carry signals in the form of pulses of light. Each optical fiber is surrounded by a reflective cladding and an outside protective coating. The light pulses are converted to electronic signals.

Communications

Microwaves can be used to carry phone conversations over long distances. Microwaves are very short electromagnetic waves that travel through the atmosphere and make communication without connecting wires possible.

In cell phones, sound waves are changed into microwaves. They are transmitted using an antenna (sent and received) and converted back to sound waves.

Communications

Circuits, Voltage & Current

PARTS OF A CIRCUIT An electric circuit is a combination

of parts connected from a complete path through which electrons can move.

The purpose of a circuit is to make use of energy of moving electrons.

Therefore a circuit is a system of parts, or components by which electric energy can be changed into other forms of energy.


HEAT, LIGHT & MAGNETISM A basic complete circuit has four

parts: The energy source the conductors the load and the control device.


Conductor Wires

Energy

Source

Battery

Light

Switch


ENERGY SOURCES Produces the force that causes electrons

to move. Similar to a pump that forces water

through a pipe. In electricity, this force is called voltage

or electromotive force. Chemical Cells and electromagnetic

generators.


Because electrons are negatively charged, they are attracted by positive charges and repelled by negative charges.

If two charged objects are connected by a conducting material such as wire, electrons will flow from the negative object to the positive object.

The flow of electrons is called current.


To produce a continuous electric current in the wire, energy must be supplied continuously.

Electrons are not used up as they move through a circuit.

Therefore the number of electrons that return to the positive terminal of the power source equals the number of electrons that leave the negative terminal of that energy source.


- ----

- +++

-

--++++++

NEG. CHARGED OBJECT

POS. CHARGED

OBJECT


---- -+

++

-

--++++++

NEG. CHARGED OBJECT

POS. CHARGED

OBJECT

-

FLOW OF

ELECTRONS


CONDUCTORS in a circuit, conductors provide an

easy path through which electrons can move through the circuit.

Copper is the most commonly used conductor metal.

Fashioned into wire or channels, copper wire may be bare or covered with some kind of insulating material.


The insulation wire provides a method to prevent the conductors (wires) from touching each other or some other conducting surface.

It prevents a short. In some circuits, metal objects

other than copper conductors form the conducting paths.


Laminated circuit boards or bread boards are conductors.

Lets look at the bread board.


Breadboards are used for testing and experimenting with electronic circuits.

They are very convenient since all you have to do is plug in the components.

On the surface of a breadboard, there are many holes for plugging in components:


The bread board has many strips of metal which run underneath the board that connects the component. The metal strips are laid out as shown below:


Each strip is a connection. So whichever components connected to a certain strip are connected to each other.

The blue strips shown in the illustration are usually used for connecting the batteries and the green strips are for the components.


LOAD The part of the circuit that changes

the energy of moving electrons into some other useful form of energy.

A light bulb is a very common circuit load.

As electrons move through the filament of the lamp, the energy of the electrons in motion is changed into heat energy and light energy.


Loads can be connected into a circuit in series and parallel or in series-parallel combinations.

A series circuit provides only one path or one loop through which electrons can move from one terminal of the energy source to the other.


In a parallel circuit there may be two or more different paths, or loops.

A series-parallel circuit has a combination of both parallel and series circuits in a single circuit.


CONTROL DEVICE: The mechanical wall switch is an

example of a simple circuit control.

When the switch is in the on position, it acts as a conductor to keep electrons flowing continuously through the circuit.

The circuit is said to be CLOSED or a closed loop.


When the switch is in the off position, the circuit path is interrupted.

Electrons can no longer move through the circuit.

The circuit is said to be OPEN or an open loop.

Different types of control devices.


VOLTAGE: As stated earlier, the energy that

forces electrons through a circuit is called the electromotive force.

The EMF is measured in units called volts.

It is referred to voltage. Most homes operate on 120. A common flashlight battery

produces 1.5 volts


CURRENT: The movement of electrons is

called current. It is measured in amperes or

amps. One ampere of current is equal to

one coulomb (6,240 quadrillion) of electrons passing past any point in a circuit during one second of time.


A 100 watt light bulb requires about .8 amps of current to operate.

Most starters in cars use 200 amps when it is switched on.

VOLTAGE AND CURRENT REQUIREMENTS:

Sources od energy must be able to do two things.

Supply the voltage Deliver the current as required by the

device.


You can connect 8 flashlight dry cells together in such a way as to form a battery that produces 12 volts.

However you would never get the car to start with this energy source.

In order to do that a larger battery also producing 12 volts but having a much larger current-delivering capacity must be used.


It is important to know both the voltage and current requirements are often given on the name plates attached to these products.

DIRECT CURRENT (dc) Is produced in a circuit by a

steady voltage source.


That is, the positive and negative terminals, or poles, of the voltage source do not change their charges over time.

These terminals are said to have fixed polarity.

Therefore the direction of the current does not change over time.

Such a voltage is provided by electric cells, batteries and dc generators.


DC may be constant, or steady, in value.

The current also may be varying or pulsating.

The applied voltage and the nature of the load determine the kind of direct current supplied.


ALTERNATING CURRENT (ac) produced by a voltage source that

changes polarity, or alternates, with time.

The current moves in one direction and then another direction over time.

The most common source is a an alternating current generator or alternator.


For purposes of our project we will be using DC power.


RESISTANCE To better understand what

resistance is, you must first get an idea of how electrons flow.

When an electron is knocked out of an atom, it will fly off and hit another atom. If the electron strikes the atom with enough force, it will knock off another electron. The atom that was just knocked off will hit another atom and so forth.


Note that every time an electron strikes another, it is transferring its energy. Some of the energy is converted into heat every time it is transferred.

The voltage will drop as the energy is transferred over long distances.

Thus a long wire has a higher resistance than a short wire.


Some materials - such as copper and silver - does not hold on to its electrons very tightly.

Therefore it doesn't require much energy to knock off an electron.

These materials are called conductors and has a very low resistance to electron flow.


Materials such as clay and plastics hold on to their electrons more tightly than conductors. It takes more energy to knock off an electron from these materials. These materials are called insulators and has a high resistance to electron flow.

Now, you must understand that this is NOT how electrons really flow; It serves only as something for you to work with. To really know how electrons flow, which we will not get into, you will need to study quantum physics


Resistance is represented by the letter R.

The basic unit of measure is ohm or the symbol (Greek omega).


OHM’S LAW Ohm's law is one of the most important

concepts in electronics. Fortunately it's only a very simple mathematical relationship between current, voltage, and resistance.

According to the Ohm's law, voltage equals current times resistance which is expressed in the following equation:

E=IR where E = voltage, I = current, and R =

resistance


For example, ifI = 0.1AR = 10kthen E = 0.1 * 10kE = 1000 volts See excel spreadsheet: Ohms Law

Note: "k" stands for "thousands". So 10k =

10,000 ohm


COMPONENTS

Resistors are one of the most commonly used components in electronics.

As its name implies, resistors resist the flow of electrons.

They are used to add resistance to a circuit.


The color bands around the resistors are color codes that tell you its resistance value.

Recall that resistance is measured in ohms.


The tolerance bands indicates the accuracy of the values. A 5% tolerance (gold band) for example, indicates that the resistor will be within 5% of its value. For most applications, a resistor within 5% tolerance should be sufficient.


To get the value of a resistor, hold the resistor so that the tolerance band is on the right.

The first two color bands from the left are the significant figures - simply write down the numbers represented by the colors. The third band is the multiplier - it tells you how many zeros to put after the significant figures. Put them all together and you have the value.


One last important note about resistors is their wattage rating. You should not use a 1/4 watt resistor in a circuit that has more than 1/4 watt of power flowing.

For example, it is NOT okay to use a 1/4 watt resistor in a 1/2 watt circuit. However, it is okay to use a 1/2 watt resistor in a 1/4 watt circuit.


CAPACITORS

Capacitors are the second most commonly used component in electronics.

They can be thought of as tiny rechargeable batteries.

Capacitors can be charged and discharged.


• Ceramic capacitors are brown and has a disc shape. These capacitors are non-polarized, meaning that you can connect them in any way. To find the value, you simply decode the 3 digit number on the surface of the capacitor. The coding is just like the resistor color codes except that they used numbers instead of colors. The first 2 digit are the significant figures and the third digit is the multiplier.

These capacitors are measured in pF.


Electrolytic Capacitors has a cylinder shape. These capacitors are polarized so you must connect the negative side in the right place. The value of the resistor as well as the negative side is clearly printed on the capacitor. These capacitors are measured in µF.


DIODES Diodes let electrons flow through

them only in one direction. Diodes flow from cathode to anode. The cathode side of the diode is marked with a band around it


Light Emitting Diodes (LED for short) are just like the regular diodes except that it lights up when electrons are flowing through. Note: there aren't any bands to identify which pin is anode and which is cathode. However, one pin is longer then the other. The longer pin is the anode, the positive side.


TRANSISTORS Transistors are used as switches

and amplifiers. We will discuss two types of transistors: PNP and NPN transistors. Both of these transistors has 3 pins: emitter, base, collector.

PNP

NPN


To allow electrons to flow through the collector and emitter of a PNP transistor, the following must apply:The emitter is more positive than the base and the collector leads to the negative

The NPN transistor is the opposite:The collector must be more positive than the base and the emitter leads to the negative.


INTEGRATED CIRCUITS (chips) Logic circuits -

These IC's are basically decision makers. most contain logic gate circuits. (logic gates will be discussed in a later section).

Comparators - These IC's compare inputs and gives an output.

Operational Amplifiers - These are amplifiers. Works very much like transistor amplifier circuits.

Audio amplifiers - These are used to amplify audio.


Timers - These are counting IC's used for circuits that counts or needs to keep track of time.

Switches - Switching IC's are also very much like the switching circuits of transistors


SPST = Single Pole, Single Throw This is a two terminal switch that opens and closes a circuit.

SPDT = Single Pole, Double Throw This is a three terminal switch that connects one terminal to either of the other two.

DPDT = Double Pole, Double Throw This is a six terminal switch that connects a pair of terminals to either of the other two pairs.


SCHEMATIC DIAGRAM A schematic diagram shows how

each component connect with another.

It is a simple and easy to read outline of the circuit.

Each type of component has a unique symbol and a name(usually 1-2 letters).


All relevant values and component specific information are usually included.

Below is an example of a schematic diagram:


The 4 horizontal lines is the battery. The triangle in the circle represents the light emitting diode and the wavy lines represent the resistor -- both of which will be discussed in the components section.


Lets Build this one together!

R 1

batteryled


SAMPLE CIRCUITS

http://library.thinkquest.org/16497/projects/beginner/index.html#BEGINNER%20CIRCUITS


Video: Cyborg Technologies CYBORG MASKS (see Cyborg Mask

Project.doc)

We won’t be quite that complex. We will create an electronic device that will depend upon simple parallel circuits and a developed code to communicate.

http://cyborg-technology.com/#page

http://cyborg-technology.com/#page

Principles of Engineering in Communications Engineering Concepts.

Documents

Transcript of Principles of Engineering in Communications Engineering Concepts.