Internet of Things and its Applications

Things and Connections Question & Answer

Question : 1
Why do you connect the wire mesh conductor of a coaxial cable to the ground?

Answer :

In order to avoid the interference caused by the electromagnetic noise. the voltage induced by electromagnetic interference (EMI) is sent to earth by grounding the outer conductor of a coaxial cable.

Question : 2

What are the advantages of Optical fiber?

Answer :

The advantages of Optical fiber are:

It can handle much higher bandwidth than copper. Due to the low attenuation, repeaters are needed only about every 30 km on fiber lines versus about every 5 km for copper.
Fiber is not affected by power surges, electromagnetic interference or power failures. It is not even affected by corrosive chemicals in the air, making it ideal for factory environments where electrical interference is very high.
Fiber cable is lighter than copper cable. One thousand twisted pair copper cables of 1 km long weigh 8000 kg. But fibers have more capacity and weigh only 100 kg, which greatly reduces the need for expensive mechanical support systems that must be maintained.
Fibers do not leak light and are quite difficult to top. This gives them excellent security against potential wire-tappers.
Write one advantage and disadvantage of Microware Transmission.

Question : 3

Write one advantage and disadvantage of Microwave Transmission.

Answer :

Advantage of Microware Transmission is:

Carries 1000's of voice channels at the same time.
Disadvantage of Microware Transmission is:
It is very costly.

Question : 4

Write one advantage and disadvantage of Satellite Microware

Answer :

Advantages of satellite Microware

A single microware relay station which is visible from any point.
Disadvantages of Satellite Microwave.
Cost of launching satellite is very expensive.

Question : 5

Write one application of Infrared Waves.

Answer :

Infrared waves has established standards for using these signals for communication between devices such as keyboards, mouse, PCs and printers.

Question : 6

Write advantage of Unshielded Twisted Pair Cable.

Answer :

Advantages of Unshielded Twisted Pair Cable are:

Installation is easy.
Higher grades of UTP are used in LAN technologies like Ethernet.
Flexible and Cheap.

Question : 7

Write disadvantages of Unshielded Twisted Pair Cable.

Answer :

Disadvantages of Unshielded Twisted Pair Cable are:

Bandwidth is low when compared with Coaxial Cable.
Provides less protection from interference.

Question : 8

Write advantages and disadvantages of shielded Twisted Pair Cable.

Answer :

Advantages of Shielded Twisted Pair Cable are:

Easy to install and can be used for Analog or Digital transmission.
Higher capacity than unshielded twisted pair.
Eliminates crosstalk.
Disadvantages of Shielded Twisted Pair Cable are:
Difficult to manufacture
Heavy

Question : 9

Write short note on Application layer of OSI stack.

Answer :

The data to be transmitted is obtained from this layer with the help of various applications such as web, ftp, telnet etc, these applications will have data in different formats such as binary, ASCII, EBCDIC etc.

Question : 10

What is the usage of transport Layer?

Answer :

It does flow control, fragmentation, reassembly of the data to be transmitted or received.

Question : 11

Write short note on TCP.

Answer :

TCP is a connection-oriented transport protocol. TCP provides end-to-end reliable services. Each TCP connection has only two endpoints. The data transmitted over a TCP connection is error-free, not lost, not duplicated, and arrives in order. TCP provides functions such as timeout and retransmission management, window management, traffic control, and congestion control to ensure that TCP provides reliable services.

Question : 12

Write important characteristics for IOT Protocols.

Answer :

The important characteristics for IOT Protocols are:

Speed: Amount of data that can be transferred/second.
Latency: amount of time a message takes to be transferred.
Power consumption.
Security
Availability of software stacks.

Question : 13

Why MQTT is considered better than HTTP in IoT?

Answer :

HTPP is the best known protocol that powers the Web (WWW). However because of the high protocol overhead HTPP is not likely to be a major IOT protocol. MQTT (Message Queuing Telemetry Transport) has emerged as the main IOT messaging protocol because it is lightweight and easy to use.

Question : 14

Write disadvantage of Coaxial Cable.

Answer :

Disadvantage of Coaxial Cable are:

It tends to be more ridged and more difficult to bend around tight corners.
It has a tendency to pick up signals around it unless shielded.
Imperfect shielded can cause a grounded loop.
For the most part 10 base 2 is about as fast as you will ever get on a coaxial cable without special circumstances.
It is ancient and being phased out phased out except for special use by cable companies and some telecoms.

Question : 15

Write advantages of Coaxial cable.

Answer :

Advantages of Coaxial Cable are:

It can be used for both analog and digital transmission.
It offers higher bandwidth as compared to twisted pair cable and can span longer distances.
Because of better shielding in coaxial cable, loss of single or attenuation is less.
Better shielding also offers good noise immunity.
It is relatively inexpensive as compared to optical fibers.
It has lower error rates as compared to twisted pair.
It is not as easy to tap as twisted pair because copper wire is contained in plastic jacket.

Question : 16

What are advantages of wired network?

Answer :

Reliability: Ethernet connections have been in existence much longer than Wi-Fi technology, which makes it much more reliable. They are less prone to dropped connections and are more reliable.
Speed: Wired connections are less affected by local factors like walls, floors, cabinets, length of the room, interference from other electronic devices etc. This enables wired connectivity to be much faster then wireless.

Question : 17

Write one advantage and disadvantage of wireless network.

Answer :

Advantage

Scalable: Wireless networks do not require any hardware installations. They typically involve configurations and be up and running in a short time. They can also be extended very easily.

Disadvantage

Slower speed: When dealing with real-time data, it is imperative that data is transmitted and available as fast as possible. Wireless networks are susceptible to increased latency and signal interference that impacts the speed and consistency of the data.

Question : 18

Why don you connect the wire mesh conductor of a coaxial cable to the ground?

Answer :

In order to avoid the interference caused by the electromagnetic noise. The voltage induced by electromagnetic interference (EMI) is sent to earth by grounding the outer conductor of a coaxial cable.

Question : 19

Mention the various components of signal loss in a typical fiber optic link.

Answer :

Losses are due to the following reasons:

Absorption and attenuation of the cable because the cladding is not completely opaque. So, some of the light energy is absorbed into the cladding.
Large losses result from the physical connections that bring light sources and detectors into alignment with the fiber cable.
Losses also occur between the splices which are the connectors that attach two cables together.
Misalignment of the light source to cable causes loss of light energy. The misalignments are reduced by precise fittings coupling and splices and by carefully following the connecting processes given by the manufacturer.
Loss of light also occurs because of bends in laying the cable.

Question : 20

Describe how losses occur due to the bends in fiber optic cables.

Answer :

Bends in the fiber cause reflected and refracted rays to change directions. This can increase the absorption loss and distort the light pattern at the receiving end.

Question : 21

What is the resulting effect on the light signal due to scattering?

Answer :

The effect of scattering is to attenuate the light energy as the ray travels through the core.

Question : 22

Write short note on Terrestrial microwave link

Answer :

Terrestrial microwave link

Construction: Consists of directional parabolic antennas. Both antennas are on the ground.
Range of operation: With in line of sight. Repeaters are needed for higher range of communication. Relay towers are used to extend the range
Frequency range: 4 to 6 GHz and 21 to 23 GHz.
Cost: Compared to satellite communication, the cost is low.
Bandwidth and capacity: Data rates are from 1 to 10 Mbps.

Question : 23

Explain types of control loops.

Answer :

Types of control loops are:

There are two main types of control loops:
Open loops, which operate with human input, and closed loops, which are fully autonomous. Some loops can be switched between closed and open modes. When open, a switchable loop is manually controlled and when closed it is fully automated.

Open-loop and closed-loop control
In an open-loop control system, the control action from the controller is independent of the process variable. An example of this is a central heating boiler controlled only by a timer. The control action is the switching on or off of the boiler. The process variable is the building temperature. This controller operates the heating system for a constant time regardless of the temperature of the building.

In a closed-loop control system, the control action from the controller is dependent on the desired and actual process variable. In the case of the boiler analogy, this would utilize a thermostat to monitor the building temperature, and feed back a signal to ensure the controller output maintains the building temperature close to that set on the thermostat. A closed loop controller has a feedback loop which ensures the controller exerts a control action to control a process variable at the same value as the setpoint. For this reason, closed-loop controllers are also called feedback controllers.

Question : 24

Write short notes on the following: STP, Coaxial cable, Twisted-pair wire

Answer :

They are available in different varieties.

Category 3 twisted pairs consist of two insulated wires gently twisted together. Four such pairs are typically grouped together in a plastic sheath for protection and to keep the eight wires together. Effect of noise due to (Electromagnetic Interference (EMI) is comparatively low because of shielding Being thin in size, the wires are likely to break.
Coaxial cable consists of a stiff copper wire as the core surrounded by insulating material. The signal is transmitted by the inner copper wire and it is electrically shielded by the outer sleeve. Effect of noise due to (Electromagnetic Interference (EMI) is very low. Can support up to tens of Mbps at a distance of several thousand feet. Emits very low radiation and causes less interference with the communication equipment.
Two insulated copper wires twisted together in a helical shape. The copper conductors are typically about 1 mm thick. Transmission of electromagnetic energy along the wires. Least expensive than coaxial cable. Attenuation is high because of the electromagnetic radiation of energy. Being the oldest method of data communication, ample trained man-power is available to maintain the twisted pair cables.

Question : 25

What is Clock speed ?

Answer :

The clock speed determines how many instruction per second the processor can execute. Usually clock speed is in MHz (Mega Hertz) or GHz (Giga Hertz).