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Electromagnetic Spectrum
- A wave has a trough (lowest point) and a crest (highest point).
- The horizontal distance between two consecutive troughs or crests is known as the wavelength.
- Frequency refers to the number of complete wave cycles that pass a given point in a certain amount of time, usually one second. o It is measured in Hertz (Hz)
- Wavelength and frequency are inversely proportional: that is, the shorter the wavelength, the higher the frequency, and vice versa.
- The vertical distance between the tip of a crest and the wave’s central axis is known as its amplitude. This is the property associated with the brightness, or intensity, of the wave.
Fig: Frequency increases and wavelength decreases as we
move from left to right.
❖ Telecommunication:-
Telecommunication is the technology of sending signals, messages, or data over long distances using various devices and media. Types of Transmission Mediums:
- Wired Communication o Copper wire → Traditional telephone lines. o Co-axial wire → Used in cable TV and broadband o Optical fibre → It transmits data by the passage of light through a thin transparent fibre made up of silica or glass; where data is transmitted via a process called Total Internal Reflection (TIR). ✓ This technology transmits data without any considerable intensity loss over very long distances. ✓ It can carry internet, data, TV signals, etc
- Wireless Communication o Radio Waves: ✓ Less Frequency → Bluetooth, RFID ✓ High Frequency → Wi-Fi o Microwaves → Used in mobile phones and satellite communication o Infrared (IR) → Used in TV remotes, CCTV night vision cameras o Visible Light → Used in Li-Fi (Light Fidelity), which is a new technology for ultra-fast wireless data transfer using LED lights ❖ **Wireless Network
- Near Field Communication (NFC)**
- Near Field Communication (NFC) is a short-range wireless communication technology that works within a distance of 4 cm or less.
- It is a two-way communication
- This technology is a simple setup which offers a low-speed connection when brought in contact. ➢ It can store data only up to 5 to 12 KB.
- It uses radio frequencies around 13.56 MHz to enable secure and contactless data exchange between devices.
- For Example: metro or bus cards, contactless payment via credit cards. 2. Radio Frequency Identification (RFID)
- RFID is a type of NFC with specific physical data to establish an identity of a person or object.
- It is a one-way communication
- Range: Typically up to 100 meters, depending on the device class.
- Architecture: Follows a master-slave model, where one device (master) controls communication with one or more devices (slaves).
- The Bluetooth Special Interest Group (SIG) is a network of member organisations that are the caretakers and innovators of Bluetooth® technology. About Bluetooth
- The name Bluetooth dates back more than a millennium to King Harald “Bluetooth” Gormsson, who was well known for two things: o Uniting Denmark and Norway in 958. o His dead tooth, which was a dark blue/grey colour, and earned him the nickname Bluetooth
- In 1996, three industry leaders, Intel, Ericsson, and Nokia, met to plan the standardisation of this short-range radio technology to support connectivity and collaboration between different products and industries. During this meeting, Jim Kardach from Intel suggested Bluetooth as a temporary code name.
- Logo: The Bluetooth logo is a bind rune merging the Younger Futhark runes (Hagall) (ᚼ) and (Bjarkan) (ᛒ), Harald’s initials. 4. WiFi :-
- Wi-Fi stands for Wireless Fidelity, and it is a wireless communication technology that uses radio waves to connect devices to a local area network (LAN) and access the internet.
- Wave Type : Uses relatively longer wavelength radio waves.
- Frequencies: Most modern routers support dual-band (2.4 GHz + 5 GHz) for flexibility. o 2.4 GHz → Longer range, but lower data transmission speed. o 5 GHz → Shorter range, but higher data transmission speed.
- Functionality: Wi-Fi is not the internet itself; it is a wireless signal used to transmit internet data from a router to connected devices.
- Hotspot :-
- A hotspot is a physical location where one can find an internet connection.
- Example: Turning on the mobile hotspot to connect a laptop to the internet.
- Wi-Fi Direct :-
- WiFi Direct is a method that allows two Wi-Fi-enabled devices to communicate directly with each other without connecting to an existing network or access point.
- Wi-Fi Direct enables mobile phones, cameras, printers, PCs, and gaming devices to create their own Wi-Fi networks without an internet connection. 7. Li-Fi :-
- Li-Fi (Light Fidelity) is a bidirectional wireless system that transmits data via visible light (LEDs) and infrared light
- Li-Fi is a type of Visible light communication system.
- It has a speed of more than 200 Gbps.
- White-Fi:-
- It uses the unused spectrum in frequencies used for broadcasting of television signals.
- Frequency: 450 - 580 MHz 9. Satellite Internet (Space-Based Internet) :-
- Satellite internet provides internet access through communication satellites, allowing users to connect to the internet wirelessly even in areas where traditional broadband services are unavailable.
- It is very useful for providing internet connectivity in the remotest part of the country and at difficult terrains.
- This can be divided into two: o LEO Satellite Constellation: Thousands of satellites are required for global coverage. ✓ Example: Starlink has launched more than 7,000 satellites to provide space-based internet. ✓ Latency: 20 - 30 milliseconds
- eSIM: An embedded SIM, or eSIM, is a new, emerging format in which the SIM is embedded directly into the device and is therefore not removable. o Mobile storage is used to store all the information related to a SIM card. The advantage of an eSIM is that it allows you to change phones without transferring SIM cards; the mobile operator transfers the account information remotely.
- IMEI: International Mobile Equipment Identity (IMEI) is a unique number that is used to identify a device on a mobile network. It has 15 digits and is like your phone’s unique identity. o If you have a dual SIM phone, then you will have two IMEI numbers, one for each slot. o Equipment Identity Register (EIR): It is a network entity that stores a list of IMEI numbers that corresponds to physical handsets. Check IMEI Number Device manufacturers print it on stickers and paste them on the device and its box. It is usually found on the back of your phone, under the battery pack. However, the easiest way to find it is to dial *#06# on your mobile, and your screen will immediately display the IMEI number of your current device. GSM vs CDMA Global System for Mobile Communication (GSM) Code Division Multiple Access (CDMA)
- Supports transmitting data and voice simultaneously.
- Built-in encryption was not provided (not highly secure)
- Worldwide roaming was provided.
- Uses TDMA (Time Division Multiple Access) and FDMA (Frequency Division Multiple Access). FDMA divides the available radio frequency bandwidth into multiple channels, and TDMA divides each channel into time slots. - Voice call service; providing better voice quality - SIM was encrypted with mobile; communication was secure - No data services was provided - Uses direct sequence spread spectrum to allow multiple users to share the same frequency. Extra Edge
- GSM: GSM services use different frequencies (850, 900, 1800, 1900 MHz), affecting voice quality. GSM is used mostly across Europe, Asia and West Asia.
- CDMA: Reliance Communications (formerly Reliance Infocomm) was an early adopter of CDMA, with the operator launching commercial services in May 2003. Most CDMA
deployments were on the 850 MHz band, resulting in better voice quality and fewer call drops. CDMA is available only in a few Asian countries and the US. Generations of Mobile Network :- I. 1G (Voice Calls): Launched in the late 1970s in Japan, 1G was the first generation of mobile telecommunication technology that offered voice calls only.
- Used Analogue Telecommunication: Came with low sound quality, low coverage, and without any roaming support
- Speed: 2 Kbps II. 2G (Telephony Service): In 1991 2G was introduced.
- Digital cellular technology was used.
- Apart from introducing the CDMA and the GSM concepts, it allowed users to roam and offered small data services like SMS and MMS.
- Speed: 14 Kbps to 64 Kbps III. 3G (Age of Applications): The introduction of 3G services was in 2001. It promised four times faster data transmission with access to mobile Internet.
- Integrated High-quality Audio-Video Data: This is the generation that brought emails, navigational maps, video calling, web browsing and music to mobile phones.
- Speed: 2 mbps IV. 4G (Age of Internet Calling): High speed, high quality, high capacity voice and data services – that’s the promise that 4G, the network most of us use today, brought with it around 2011.
- Compared to 3G, a phone on a 4G network got quicker response to its requests (lower latency). This is what made our phones more like hand held computing devices.
- Speed: 200 Mbps - 1 Gbps. V. 5G (IOT and Enterprises): This is the era of Internet of Things (IOT), AI and Cloud based services.
- The generation was introduced in 2016.
- It is nearly 20 times faster than 4G.
- Hailed as the new frontier of mobile technology, 5G promises latency (the delay users face as data make a round trip) of just one millisecond compared to 50 milliseconds of a 4G network.
i. Personal Area Network (PAN): o Wired → Wired earphones, connecting hard drive or pen drive o Wireless → Bluetooth ii. Local Area Network (LAN): o Wired → Ethernet is a home network where devices like computers, smartphones, and game consoles connect to a router via Ethernet cables. o WLAN (Wireless Local Area Network) → Wi-Fi iii. Metropolitan Area Network (MAN): Connects multiple LANs across a large area but is smaller than a WAN. o E.g. STD Codes, FM Radio frequencies iv. Wide Area Network (WAN): Covers country-level or global-level networks. o WWW (World Wide Web) o Country code like +91 for India Working of Internet: There are two main concepts that are fundamental to the way the Internet functions: i. Packets: Small chunks of information o A packet is a small segment of a larger message. Each packet contains both data and information about that data. ii. Protocols: These are rules and regulations designed to transmit packet data from one network to another.
- A protocol is a standardised way of doing certain actions and formatting data so that two or more devices are able to communicate with and understand each other.
- Because all Internet-connected computers and other devices can interpret and understand these protocols, the Internet works no matter who or what connects to it. Understanding Key Terms
- IP Address : An Internet Protocol (IP) address is the unique identifying number assigned to every device connected to the internet. o Two Versions of IP Address: IP addresses have two distinct versions or standards. ✓ IPv4: The Internet Protocol version 4 (IPv4) address is the older of the two, which has space for 4.3 billion IP addresses and is assigned to all computers. An IPv4 address uses 32-bit binary
numbers to form a unique IP address. It takes the format of four sets of numbers, each of which ranges from 0 to 255 and represents an eight-digit binary number, separated by a period point. ▪ Example: 192.168.1. ✓ IPv6: The more recent Internet Protocol version 6 (IPv6) has space for trillions of IP addresses, which accounts for the new breed of devices in addition to computers. ▪ Example: 28:4b:5cda:
- Uniform Resource Locator (URL): It is the address of a given unique resource on the web. o In other words, URL is the web address of a specific webpage or resource on the internet. o Example: pwonlyias.com → URL
- WWW (World Wide Web): WWW is defined as the collection of different websites around the world, containing different information shared via local servers (or computers). o WWW is an interconnected network of websites and documents that can be accessed via the Internet.
- Big Data: Big data refers to the enormous amount of complex data that we produce.
- Data Fiduciary: These are the companies/institutions who manage these complex data & convert them into some meaningful information. o Working: Tracking consumer behaviour and shopping habits to deliver hyper-personalised retail product recommendations tailored to individual customers. o Example: Meta, X, Alphabet Inc.
- VPN (Virtual Private Network): A VPN hides your IP address by letting the network redirect it through a specially configured remote server run by a VPN host. This means that if you surf online with a VPN, the VPN server becomes the source of your data. o This means your Internet Service Provider (ISP) and other third parties cannot see which websites you visit or what data you send and receive online.
o Cyberterrorists are malicious hackers which cause massive damage to the government, systems and public infrastructure. It will leave a country in fear of further attack. IV. Cyber Crime: It is an unlawful act wherein a computer is either a tool or a target or both. o It involves criminal activities that are traditional in nature, such as theft, fraud, forgery, defamation, mischief etc. o It may affect the victim's physical, mental or emotional well being. Fig: Data compiled by the National Cyber Reporting Platform (NCRP), under the Ministry of Home Affairs, shows fraudsters cheated people of Rs 551 crore in 2021, Rs 2, crore in 2022, and Rs 7,496 in
Types of Cyber Attacks
- Malware: Malware is a Portmanteau term consisting of “malicious” and “software.” o Malware is a catch-all term for any type of malicious software designed to harm or exploit any programmable device, service or network
2. Adware: The least dangerous and most
lucrative malware. Adware displays ads on your computer. o Example: In 2003, CoolWebSearch, an adware program that acted as a digital hijacker, took over web browsers without user consent. By redirecting internet searches to its sites and bombarding users with ads, it proved both annoying and highly lucrative. It has been
said to raked in over $300 million annually, highlighting the immense profitability of adware.
3. Spyware: Spyware is software that spies on you, tracking your internet activities in order to
send advertising (Adware) back to your system. o Example: FinFisher, also known as FinSpy or Wingbird is a commercial spyware application employed by law enforcement and government agencies across the globe. It possesses the capability to collect diverse credentials, retrieve file listings, recover deleted files, access various documents, Livestream or record data, and gain control over webcams and microphones.
4. Virus: A virus is a contagious program or code that attaches itself to another piece of
software, and then reproduces itself when that software is run. Most often this is spread by sharing software or files between computers.
5. Spam: Spamming is a method of flooding the Internet with copies of the same message. Most
spams are commercial advertisements which are sent as an unwanted email to users. o Spams are also known as Electronic junk emails or junk newsgroup postings. These spam emails are very annoying as they keep coming every day and keep your mailbox full. o Example : ‘You Have a Package Delivery’, with frequent deliveries from e commerce websites, a text about a package or order might seem normal.
6. Worm: A program that replicates itself and destroys data and files on the computer. Worms
work to "eat" the system operating files and data files until the drive is empty.
12. Ransomware: If you see this screen that warns you that you have been locked out of your
computer until you pay for your cybercrimes. Your system is Key severely infected with a form of Malware called Ransomware. Even if you pay to unlock the system, the system is unlocked, but you are not free of it locking you out again. o Example: The WannaCry Ransomware attack reverberated globally, affecting organisations across continents. This high-profile cyber attack swiftly propagated through interconnected computer networks in May 2017. Prominent victims included FedEx, Honda, Nissan, and the UK’s National Health Service (NHS). Fig: How a Ransomware Attack Works
13. Browser Hijacker: When your homepage changes to one that looks like those in the images
inserted next, you may have been infected with one form or another of a Browser Hijacker. This dangerous Malware will redirect your normal search activity and give you the results the developers want you to see. o Its intention is to make money off your web surfing. Using this homepage and not removing the Malware lets the source developers capture your surfing interests.
14. Phishing: This is a common form of cyber attack where attackers impersonate legitimate
organisations to trick individuals into providing sensitive data. For example, fraudsters often send deceptive emails that appear to be from reputable banks to gather personal information from unsuspecting individuals. o Example: Google and Facebook Phishing Attack (2013-2015), when Evaldas Rimasauskas who pleaded guilty in 2019, masterminded a sophisticated scheme that involved creating a fictitious company and sending phishing emails to employees at Facebook and Google. This elaborate ruse ultimately swindled these tech giants out of over $100 million.
15. Password Attacks: An attempt to obtain or decrypt a user's password for illegal use.
Hackers can use cracking programs, dictionary attacks, and password sniffers in password attacks. o Defence against password attacks is rather limited but usually consists of a password policy including a minimum length, unrecognisable words, and frequent changes.
16. Denial of Service (DoS) attack: A denial-of-service (DoS) attack is a malicious attempt to
overwhelm a web property with traffic in order to disrupt its normal operations. o Distributed Denial of Service (DDoS): Distributed denial of service (DDoS) attacks are a subclass of denial of service (DoS) attacks. A DDoS attack involves multiple connected online devices, collectively known as a botnet, which are used to overwhelm a target website with fake traffic.
17. Man in the Middle (MITM): A man-in-the-middle (MITM) attack is a form of cyberattack in
which criminals exploiting weak web-based protocols insert themselves between entities in a communication channel to steal data. o None of the parties sending email, texting, or chatting on a video call are aware that an attacker has inserted their presence into the conversation and that the attacker is stealing their data.
❖ Supercomputers :-
- Supercomputers: Supercomputers are computing devices based on parallel processing where thousands of processors are connected parallel to each other. o Supercomputers can handle extremely large data in a very short span. o Processing ability of supercomputers is thousands of times greater than normal computers. o A supercomputer consumes a lot of space and energy.
- Speed of Supercomputers : Their speeds and processing abilities are measured in FLOPs (Floating Point Operations per second). o TerraFLOPs = 1012 FLOPs o PetaFLOP = 1015 FLOPs o ExaFLOPs = 1018 FLOPs
- Top 500 Supercomputers: TOP500 List is released twice a year. o As per November 2024 List top 5 supercomputers are; ✓ El Capitan → United States (1.742 ExaFLOPs) ✓ Frontier → United States (1.353 ExaFLOPs) ✓ Aurora → United States (1.012 ExaFLOPs) ✓ Eagle → United States ✓ HPC6 → Italy
- India: o AIRAWAT - PSAI is ranked 136 → Center for Development of Advanced Computing (C- DAC) ✓ Speed: 8.50 PetaFLOPs o Arka is ranked 188 → Indian Institute of Tropical Meteorology ✓ Speed: 5.94 PetaFLOPs o Arunika is ranked 189 → National Centre for Medium Range Weather Forecasting ✓ Speed: 5.94 PetaFLOPs o Pratyush is ranked 268 → Indian Institute of Tropical Meteorology ✓ It is not indigenously built, rather taken from Cray Supercomputer, an USA-based company. Fig: Supercomputers use more than one central processing unit (CPU).
o Arka AI/ML is ranked 400 → Indian Institute of Tropical Meteorology o Mihir is ranked 431 → National Centre for Medium Range Weather Forecasting. Application of Supercomputers Supercomputers embody the dual edge of technology - powerful tools for both welfare and warfare.
- Quantum Physics: For studying Standard Model particles—analyzing their shape, size, and mass.
- Nanotechnology: In discovering new nanomaterials and enhancing nano scale innovations.
- Geological and Weather Forecasting: Systems like Arka and Arunika can improve global weather models, enhancing horizontal resolution from 12 km to 6 km and enabling block- level forecasts.
- Climate Change Research: For modeling and analyzing environmental data to study global climate patterns.
- Drug Discovery and Vaccine Development : To simulate biological processes and accelerate pharmaceutical research.
- Nuclear Technology : In the design, development, and testing of nuclear reactors and weapons.
- Artificial Intelligence (AI): For training large-scale AI models and enabling advanced machine learning applications.
- Extended Reality : In developing Virtual Reality (VR) and Augmented Reality (AR) environments.
- Blockchain and Data Mining : To process and analyze vast amounts of transactional and cryptographic data.
- Financial Modeling : For predictive analytics in stock market trends and economic forecasting. Development of Supercomputer
- 1960s: US company SeymourCray started developing supercomputers. They named their supercomputer Cray Supercomputer.
- 1974: Pokhran Nuclear test which was the first atomic explosion testing of India. Technology denied by Western Nations India faced major setbacks when Western countries denied it access to advanced technology on two key occasions. The first was in the 1970s, which slowed down India’s space program. The second was in the 1980s, when India was stopped from building supercomputers. But instead of giving up, India took this as motivation and went on to create its own low cost, homegrown technologies in the years that followed.
