Physical Layer and Media (Part 2)

Summary

This educational session delves into the fundamentals of the physical layer of communication, focusing on analog and digital signals. It explains the nature of these signals, using examples like room temperature variation to illustrate signal representation. The session further explores various physical media, including copper cables, fiber optics, and wireless transmission, detailing their components and signaling methods. By comparing these media, learners gain insights into the differences and applications of each, enhancing their understanding of signal transmission in modern communication systems.

Takeaways

• 📶 The session aims to teach learners about analog and digital signals, different physical layer media, and how to compare them.
• 📉 A signal represents the variation of a physical quantity over time, such as the change in room temperature throughout a day.
• 🔁 Analog signals can take any value within a defined range and are continuous, representing real-life phenomena like colors, temperature, and sound.
• 🔢 Digital signals are discrete, taking on a finite number of values at any given time, and are used in systems that require time and magnitude discretization.
• 📈 The physical layer media can be categorized into wired and wireless, with each focusing on the transmission of signals.
• 🛰 Wired media includes copper cables, which can be either Unshielded Twisted Pair (UTP) or Shielded Twisted Pair (STP), and are used for electrical signal transmission.
• 🌐 Fiber optic cables are another type of wired media that transmit light signals, using either single mode or multimode fibers, and require specific components like lasers or LEDs.
• 🔌 Connectors such as RJ45 for UTP and specific NICs are essential physical components for establishing connections in wired networks.
• 📡 Wireless media relies on access points for devices like mobile phones to connect to networks via Wi-Fi, using radio waves for signaling.
• 📳 Wireless NICs in devices convert data into radio waves for transmission, requiring components like radios and antennas for communication.
• 🔄 The comparison of physical media highlights the differences in signaling methods, with copper using electromagnetic signals and fiber optics using light pulses, while wireless uses radio waves.

Q & A

What is the main focus of the session on the physical layer and media?

The session focuses on understanding analog and digital signals, knowing various physical layer media, and comparing different physical media.

What is a signal in the context of the physical layer?

A signal is a function that represents the variation of a physical quantity with respect to time, such as the change in room temperature over a 24-hour period.

What are the two kinds of signals discussed in the session?

The two kinds of signals discussed are analog signals and digital signals.

How is an analog signal defined in the session?

An analog signal is defined as a signal that can take any value in the defined range and is continuous in nature, representing real-life phenomena like colors, temperature, and sounds.

What is the key difference between an analog and a digital signal?

The key difference is that an analog signal can take any value within a range and is continuous, while a digital signal can only take on a finite number of values at a given time, discretizing both time and magnitude.

What are the physical components involved in copper cable communication?

The physical components in copper cable communication include Unshielded Twisted Pair (UTP), Shielded Twisted Pair (STP), coaxial cables, connectors like RJ45, and Network Interface Cards (NICs).

What are the types of fiber optic cables mentioned in the session?

The types of fiber optic cables mentioned are single mode fiber, which produces a single straight path for light, and multimode fiber, which allows multiple paths and can result in dispersion.

What is the main physical component required for fiber optic communication?

The main physical components required for fiber optic communication are lasers or light-emitting diodes to generate light signals.

What is the role of an access point in wireless media?

An access point in wireless media serves as a connection point for devices like mobile phones, allowing them to connect to a network via Wi-Fi.

How do wired and wireless media differ in terms of the signals they use?

Wired media, such as copper cables, use electromagnetic signals, while wireless media use radio waves to transmit information.

What is the purpose of a Network Interface Card (NIC) in wireless communication?

In wireless communication, a NIC converts the physical data into radio waves, allowing the transmission of data through the air via antennas.

Outlines

00:00

📡 Introduction to Physical Layer Media and Signals

The session begins with an introduction to the physical layer and media, focusing on the learning outcomes which include understanding analog and digital signals, knowing various physical layer media, and comparing different physical media. Signals are defined as a function representing the variation of a physical quantity over time, exemplified by the daily temperature changes in a city. The distinction between analog and digital signals is made clear, with analog signals being continuous and variable, while digital signals are discrete and finite. Examples are provided to illustrate these concepts, setting the stage for further exploration of physical layer media.

05:04

🔌 Wired and Wireless Media Components and Comparison

This paragraph delves into the specifics of physical layer media, starting with wired media such as copper cables, which include Unshielded Twisted Pair (UTP) and Shielded Twisted Pair (STP), and coaxial cables used for audio or video communication. Connectors like RJ45 and the role of Network Interface Cards (NICs) in wired networks are discussed. The explanation then shifts to fiber optic cables, highlighting the differences between single mode and multimode fibers and the components like lasers or LEDs used in their operation. The session concludes with a look at wireless media, detailing the need for access points, wireless NICs, and the use of radio waves for signaling. The summary emphasizes the comparison of copper, fiber optic, and wireless media, providing insights into their physical components and signaling methods.

Keywords

💡Physical Layer

The physical layer is the first layer of the OSI model and is responsible for the actual transmission of data over a network medium. It defines the electrical, mechanical, and procedural means used to activate, maintain, and deactivate the physical link for the transfer of information. In the script, the physical layer is discussed in the context of understanding different types of signals and media used for communication.

💡Analog Signal

An analog signal is a continuous signal that can take any value within a defined range, representing a physical quantity that varies over time. It is the opposite of digital signals and is used to convey information such as sound or light. In the script, analog signals are exemplified by natural phenomena like temperature variations and are contrasted with digital signals.

💡Digital Signal

A digital signal is a discrete-time signal that can take on one of a finite number of values at any given time. Unlike analog signals, digital signals are not continuous and are used in computing and telecommunications to represent data. The script explains digital signals as signals that discretize both time and magnitude, using examples of signals that can only take values from a finite set.

💡Physical Quantity

A physical quantity is a measurable attribute of a system, such as temperature, time, or distance. In the context of the script, physical quantities are used to illustrate the concept of signals, where changes in these quantities over time can be represented as signals.

💡Wired Media

Wired media refers to communication channels that use cables or wires to transmit data. The script discusses various types of wired media, including copper cables (UTP and STP) and fiber optic cables, which are used for different types of data transmission based on the physical properties and capabilities of the media.

💡Wireless Media

Wireless media is a type of communication channel that does not require cables or wires for data transmission. It uses radio waves to transmit data over the air. The script mentions wireless media in the context of comparing it with wired media and discusses components like access points and antennas used in wireless communication.

💡Unshielded Twisted Pair (UTP)

Unshielded Twisted Pair (UTP) is a type of cable used in wired networks that consists of pairs of wires twisted together and enclosed in a single outer jacket. The script uses UTP as an example of a physical layer medium for transmitting electrical signals in wired communication.

💡Shielded Twisted Pair (STP)

Shielded Twisted Pair (STP) is similar to UTP but includes additional shielding to reduce interference from external sources. The script briefly mentions STP in the context of different types of copper cables used in physical layer media.

💡Coaxial Cable

A coaxial cable is a type of copper cable that consists of an inner conductor, a dielectric layer, and a shielded outer conductor. It is commonly used for audio and video communication. The script provides an example of a coaxial cable connecting a set-top box with a dish antenna.

💡Fiber Optic Cable

A fiber optic cable is a type of cable that uses light pulses to transmit data over long distances at high speeds. The script explains that fiber optic cables can be either single mode, which allows light to travel in a single path, or multimode, which allows for multiple paths and potential dispersion of light.

💡Network Interface Card (NIC)

A Network Interface Card (NIC) is a hardware component that connects a computer to a network. The script discusses NICs in the context of both wired and wireless networks, highlighting their role in converting data into the appropriate signal type for transmission over the network medium.

Highlights

Introduction to the second part of the physical layer and media.

Outcomes of the session include understanding analog and digital signals, knowing various physical layer media, and comparing different physical media.

Definition of a signal as a function representing the variation of a physical quantity with respect to time.

Example of representing room temperature variation in a city over 24 hours as a signal.

Differentiation between analog and digital signals.

Explanation of an analog signal as one that can take any value in the defined range and is continuous in nature.

Real-life examples of analog signals, such as colors, heat, temperature, and sounds.

Illustration of an analog signal graph with a continuous range between -7 and +7.

Definition of a digital signal as one that can take on a finite number of values at a given time.

Digital signal example showing discrete values over time.

Importance of signals in physical layer media for both wired and wireless communication.

Overview of wired media components including copper cables, UTP, STP, and coaxial cables.

Introduction to fiber optic cables, their types, and the use of light signals for communication.

Comparison of copper and fiber optic cables based on the type of signals they use.

Components of wireless media, including access points, NICs, and the use of radio waves for communication.

Explanation of the signaling method in wireless media using radio waves.

Session conclusion summarizing the understanding of analog and digital signals and the comparison of physical layer media.

Transcripts

We are now in part two of the physical layer and media.

Let's have a look at the outcomes first.

Upon the completion of this session, the learner will be able to

understand analog and digital signals,

know various physical layer media,

and finally, we will compare various physical media.

We will start the session with signals.

It is a function, that represents

the variation of a physical quantity with respect to time.

So with respect to time,

we can see the variation of a physical quantity

and that can be represented as a signal.

We will take an example.

The variation in room temperature of a city,

in one day, that is 24 hours can be represented using signals.

That is, the variation, that is this variation of a physical quantity--

the physical quantity here is the temperature of a city

and with respect to time, that is in one day, that is 24 hours.

So, we can represent this as a signal.

And what are the two kinds of signal we have?

Number one, analog signal,

and number two, digital signal.

We will see analog signal first

and then we will move on to the digital signal.

Analog signal.

It is the signal, that can take any value in the defined range.

Please note, any value.

For example, all real life signals are analog in nature.

Say the colors we see, the heat or the temperature we feel,

the sounds we produce or hear, all these signals are analog in nature.

And that is why, we call all real life signals are analog in nature.

Let's have an example.

See, this is an example analog signal

and this analog signal is continuous in nature.

For example, we have a signal which is represented as x of t

and this is in y-axis and the time is in x-axis.

Because, any signal that is with respect to time.

So, the signal x of t can take any value

between minus seven to plus seven in this example.

So here is minus seven and here is plus seven.

So this signal takes any value between minus seven and plus seven

and this is a continuous signal.

For example, if we take this is point A and this is point B.

Between point A and point B,

there can be any value and there can be infinite values.

And if we have infinite values in the defined range,

then we call this signal as an analog signal.

On the other hand, we have digital signal.

It is the signal that can take on

of the finite values at a given time.

At a given time, if it can take only finite values,

then it will be a digital signal.

Because, in digital signal,

we discretize both time and magnitude,

that is size or quantity.

Let's have an example now for digital signal.

And this is an example digital signal.

And as usual, x of t is the signal which is in y-axis

and the time which is in x-axis.

That signal x of t, can take only one value

out of zero, one, two, three, four, five, six, and seven

for any discrete value of time.

So for any discrete value of time,

if it can take only one value, then it is a digital signal.

In other words, let's say this is point A and let's say this is point B.

Between point A and point B, there may be larger values

but they are finite values.

If that is the case, then this signal will be a digital signal.

So far we have seen analog signal and digital signal.

Why do we need to deal about signals?

Because, in physical layer media,

we are ultimately focusing on signals.

We have wired media as well as wireless media.

In wired or in wireless,

the physical layer device is focusing on the signals.

Say for example,

these two are wired media and this is a wireless media.

So in this case,

it is a copper cable, where it is dealing with electrical signals.

This is an example of a fiber optic cable,

it deals with light pulses or light signals.

On the other hand, this is a wireless medium

and it deals with the microwave signals.

Because, in all the cases we are dealing with signals,

so we have learnt about the analog signals and the digital signals.

Let's have a comparison over

this copper media, fiber optic media, and this wireless media.

So we have media here.

This is copper cable, this is fiber optic cable,

and this is wireless media.

And these two are an example of wired media and this is wireless.

We will see what are the physical components in the copper cable.

We have UTP and STP.

It means Unshielded Twisted Pair cable or Shielded Twisted Pair cable.

In the upcoming lecture, we are going to practically see

the unshielded twisted pair cable

and the shielded twisted pair cable.

A coaxial cable is an example of a copper cable.

So coaxial cable, it's mainly used for audio or video communication.

And, an example is we can see this coaxial cable

that connects our set-top box with the dish antenna,

a mic set has a coaxial cable.

And we need connectors like

a connectors RJ45 kind of connectors for connecting this

UTP cable to the computer or to the networking device,

coaxial cable connectors we need.

And the physical component also include

NICs- Network Interface Cards

and in this case it is a wired network interface card.

And this network interface card

should also deal with the ports as well as interfaces.

And coming to the fiber optic cable,

it can be a single mode fiber or a multimode fiber.

A single mode fiber produces single straight path for the light.

Whereas, a multimode fiber allows multiple paths for the light.

It means, there can be dispersion.

And we need as usual connectors, NICs, interfaces,

and in this case, that fiber optic cable

we need lasers or light emitting diodes as the physical component.

Because, here, it is going to be electromagnetic signal

whereas here, it is going to be light signals.

So in the signals part, we can notice

that copper cable uses electromagnetic signals

whereas, fiber optic cable uses light signals.

So the signaling method here is

there is a light pulse which is one,

if there is no light pulse, it means it is zero.

So far we have seen wired media.

In wired media, we have seen copper cable and fiber optic cable.

Let's have a look at the wireless media.

In a wireless media, we need an access point.

If you have a mobile phone, you just turn on Wi-Fi in your mobile phone

and this Wi-Fi will connect it to your access point

and that access point will have a network at the back end.

So you will be able to connect to your network

using the wireless access points.

So we need access points, we need network interface cards,

and the network interface card, here it is going to be different.

In the previous cases, these NICs are wired NICs,

it's going to convert the physical data into electromagnetic or light signals.

Whereas, this NIC in wireless media, it is going to convert into radio waves.

The signaling method used in wireless media are radio waves.

And we need radios in order to generate the radio waves.

And we need antennae in order to send and receive.

And that's the comparison of various physical media.

I hope, you are clear with the basics of analog and digital signals,

you know the various physical layer media,

and you know how to compare various physical layer media.

I hope you guys enjoyed the session

and thank you for watching.