Overview of Modem
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This document provides an overview of modems, including: - Their history dating back to the 1950s for air defense communication needs. - Their function of modulating digital data to analog signals for transmission and demodulating analog signals back to digital data. - The main types based on connection, transmission mode, and speed of data transmission. - The basic modulation techniques used including ASK, FSK, and PSK.
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Presentation on modem
A modem is a device that modulates analog signals to transmit digital data and demodulates received analog signals to reconstruct the original digital data. It has a transmitter that converts digital to analog, a receiver that converts analog to digital, and a control unit that handles functions like auto-dialing. Modems use various modulation techniques like amplitude modulation, frequency modulation, and phase modulation. They are classified by operation mode, synchronization method, transmission medium, and modulation technique. Newer technologies like DSL provide higher speeds over telephone lines than traditional modems.
Modem presentation
The document discusses modems and their functions. It begins with listing group members and an index of topics to be covered. It then defines a modem as a device that modulates and demodulates signals to transmit digital data over analog channels. Modems are classified by transmission speed and examples are given. The document outlines the history of modems and defines types including external, internal, standard, intelligent, short-haul, and wireless. It describes the purpose of modems in converting digital to analog signals for transmission and discusses modem functions like error correction and data compression. Security and references are mentioned at the end.
Network modem
Modems allow computers to transfer data over telephone or cable lines by converting digital signals to analog and vice versa. They come in internal and external varieties and support different transmission speeds like 56kbps for X2 modems and 64kbps for ISDN. Common modem types are X2, V.90, ISDN, DSL, and cable which use different connection technologies to transmit data at varying speeds over phone lines or cable infrastructure. Proper installation and safety precautions should be followed when installing a modem.
Transmission modes (simplex, duplex & half duplex)
There are three transmission modes: simplex which allows transmission in one direction, half duplex which allows transmission in two directions but only one direction at a time, and full duplex which allows simultaneous two-way transmission. Simplex examples include television broadcasting and loudspeaker systems, half duplex includes walkie talkies, and full duplex includes telephone networks where two people can speak and listen simultaneously. Transmission modes define the direction of signal flow between communicating devices.
Modem
Modems are devices that modulate analog carrier signals to encode digital data for transmission and demodulate carrier signals to decode received data. They are used for data conversion. Modems can be classified based on their range (short haul, voice grade, wide band), the type of line used (dialup, leased), and their operation mode (half duplex, full duplex, simplex). Common types include internal and external modems. Modems work by modulating digital signals onto analog carriers for transmission and demodulating the signals back to digital on the receiving end. Modem speeds have increased significantly over time from 300 bps in the 1960s to 56 kbps in 1998 and up to 8 mbps with technologies like ADS
Modem
A modem is a device that allows computers to transmit data over telephone lines by converting digital signals to analog signals and vice versa. Modems can be external, connecting to computers through serial or USB ports, or internal, inserting directly into expansion slots inside computers. Modem standards have evolved from early speeds of 300 bps up to 56 kbps with V.90 and V.92 standards, and modem types include cable modems, DSL modems, ISDN modems, and wireless modems.
Guided and unguided media
Guided media uses physical cabling to guide transmission signals along a specific path and includes twisted pair cable, coaxial cable, and optical fiber. Twisted pair cable consists of two insulated copper wires twisted together, and can be unshielded or shielded. Coaxial cable contains two conductors separated by insulation. Fiber optic cable transmits information using pulses of light through glass cores. Unguided media uses electromagnetic waves to transmit without cabling through radio waves, microwaves, or infrared signals broadcast through free space. Radio waves can travel long distances, microwaves require line-of-sight and focused antennas, while infrared works for short-range indoor use.
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Presentation on modem
A modem is a device that modulates analog signals to transmit digital data and demodulates received analog signals to reconstruct the original digital data. It has a transmitter that converts digital to analog, a receiver that converts analog to digital, and a control unit that handles functions like auto-dialing. Modems use various modulation techniques like amplitude modulation, frequency modulation, and phase modulation. They are classified by operation mode, synchronization method, transmission medium, and modulation technique. Newer technologies like DSL provide higher speeds over telephone lines than traditional modems.
Modem presentation
The document discusses modems and their functions. It begins with listing group members and an index of topics to be covered. It then defines a modem as a device that modulates and demodulates signals to transmit digital data over analog channels. Modems are classified by transmission speed and examples are given. The document outlines the history of modems and defines types including external, internal, standard, intelligent, short-haul, and wireless. It describes the purpose of modems in converting digital to analog signals for transmission and discusses modem functions like error correction and data compression. Security and references are mentioned at the end.
Network modem
Modems allow computers to transfer data over telephone or cable lines by converting digital signals to analog and vice versa. They come in internal and external varieties and support different transmission speeds like 56kbps for X2 modems and 64kbps for ISDN. Common modem types are X2, V.90, ISDN, DSL, and cable which use different connection technologies to transmit data at varying speeds over phone lines or cable infrastructure. Proper installation and safety precautions should be followed when installing a modem.
Transmission modes (simplex, duplex & half duplex)
There are three transmission modes: simplex which allows transmission in one direction, half duplex which allows transmission in two directions but only one direction at a time, and full duplex which allows simultaneous two-way transmission. Simplex examples include television broadcasting and loudspeaker systems, half duplex includes walkie talkies, and full duplex includes telephone networks where two people can speak and listen simultaneously. Transmission modes define the direction of signal flow between communicating devices.
Modem
Modems are devices that modulate analog carrier signals to encode digital data for transmission and demodulate carrier signals to decode received data. They are used for data conversion. Modems can be classified based on their range (short haul, voice grade, wide band), the type of line used (dialup, leased), and their operation mode (half duplex, full duplex, simplex). Common types include internal and external modems. Modems work by modulating digital signals onto analog carriers for transmission and demodulating the signals back to digital on the receiving end. Modem speeds have increased significantly over time from 300 bps in the 1960s to 56 kbps in 1998 and up to 8 mbps with technologies like ADS
Modem
A modem is a device that allows computers to transmit data over telephone lines by converting digital signals to analog signals and vice versa. Modems can be external, connecting to computers through serial or USB ports, or internal, inserting directly into expansion slots inside computers. Modem standards have evolved from early speeds of 300 bps up to 56 kbps with V.90 and V.92 standards, and modem types include cable modems, DSL modems, ISDN modems, and wireless modems.
Guided and unguided media
Guided media uses physical cabling to guide transmission signals along a specific path and includes twisted pair cable, coaxial cable, and optical fiber. Twisted pair cable consists of two insulated copper wires twisted together, and can be unshielded or shielded. Coaxial cable contains two conductors separated by insulation. Fiber optic cable transmits information using pulses of light through glass cores. Unguided media uses electromagnetic waves to transmit without cabling through radio waves, microwaves, or infrared signals broadcast through free space. Radio waves can travel long distances, microwaves require line-of-sight and focused antennas, while infrared works for short-range indoor use.
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This document discusses wireless networking technologies including IEEE 802.11 (Wi-Fi), Bluetooth, and their standards and specifications. It describes the basic concepts of wireless LANs including connecting devices, medium access control, basic service sets, extended service sets, frame formats, and addressing mechanisms. It also discusses Bluetooth standards, layers, and topologies such as piconets and scatternets.
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ASk,FSK,PSK
1. Digital modulation techniques are used to modulate digital information so that it can be transmitted via different mediums. Common digital modulation methods include binary amplitude shift keying (ASK), frequency shift keying (FSK), and phase shift keying (PSK).
2. FSK conveys information by changing the instantaneous frequency of a carrier wave. It is less susceptible to errors than ASK but has a larger spectrum bandwidth. PSK varies the phase of the transmitted signal. BPSK uses two phases while QPSK uses four phases.
3. The performance of digital modulation techniques can be compared using the energy per bit to noise power spectral density ratio (Eb/N0). Lower Eb/N0 values
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Achyut S.Godbole, “ Data Communications and Networks”, Tata McGraw-Hill Publishing Company Limited, Ninth reprint, 2007
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The document discusses digital communication systems and outlines topics that will be covered, including digital data communication, multiplexing techniques, digital modulation and demodulation, and performance comparisons of modulation schemes. The objectives are to provide an overview of communication systems and concepts, discuss digital transmission methods and modulation types, and enable students to design simple communication systems and discuss industry trends.
Presentation
- Modems allow computers to transmit digital data over analog telephone lines by modulating and demodulating digital signals. They convert digital signals to audio tones that can be transmitted and received by telephone networks.
- There are three main types of modems: external modems connected via cable, internal modems installed inside computers, and PC Card modems that fit into slots on portable computers.
- When connecting, one modem modulates digital data into audio tones to send over phone lines, while the receiving modem demodulates the tones back into digital data for the receiving computer. Checksums ensure accurate data transmission.
GSM Technology
What is GSM?
The Global System for Mobile communications is a digital cellular communications system. It was developed in order to create a common European mobile telephone standard but it has been rapidly accepted worldwide.
Formerly it was “Groupe Spéciale Mobile” (founded in 1982)
now: Global System for Mobile Communication.
Services:
Tele-services
Bearer or Data Services
Supplementary services
Applications:
Mobile telephony
GSM-R
Telemetry System
- Fleet management
- Automatic meter reading
- Toll Collection
- Remote control and fault reporting of DG sets
Value Added Services
Advantages:
Better Quality of speech
Data transmission is supported
New services offered due to ISDN compatibility
International Roaming possible
Large market
Crisper, cleaner quieter calls
disadvantages:
Dropped and missed calls
Less Efficiency
Security Issues
conclusion
The mobile telephony industry rapidly growing and that has become backbone for business success and efficiency and a part of modern lifestyles all over the world.
In this session I have tried to give and over view of the GSM system. I hope that I gave the general flavor of GSM and the philosophy behind its design.
The GSM is standard that insures interoperability without stifling competition and innovation among the suppliers to the benefit of the public both in terms of cost and service quality.
ISDN Integrated Services Digital Network
Developed by ITU-T, ISDN is a set of protocols that combines digital telephony and data transport services to digitise the telephone network to permit the transmission of audio, video and text over existing telephone line. ISDN is an effort to standardise subscriber services, provide user or network interface and facilitate the inter-networking capabilities of existing voice and data networks. The goal of ISDN is to form a wide area network that provides universal end-to-end connectivity over digital media by integrating separate transmission services into one without adding new links or subscriber links.
Presentation on data communication
The document is a presentation submitted by Harpreet Kaur on data communications. It contains information on various topics related to data communications including an introduction to data communication, components of data communication such as sender, receiver, message, transmission medium and protocol. It also discusses data flow modes, analog and digital signals, types of transmission media including guided media such as coaxial cable, twisted pair cable and fiber optic cable, and unguided media. Finally, it covers networking devices such as modem, hub, switch and router.
Presentation on Modem working procedures
A modem modulates outgoing digital signals from a computer or other digital device to analog signals for a conventional copper twisted pair telephone line and demodulates the incoming analog signal and converts it to a digital signal for the digital device.
The word modem is an acronym for modulator-demodulator. Basically, a modem is used for transmitting and receiving data over a communication channel, such as twisted-pair telephone lines, coaxial cables, and optical fibers. Currently the purpose of a modem is to convert a computer’s data stream to analog format so that it can be transmitted over the analog telephone line.
At the source, modulation techniques are used to convert digital
Data (0’s and 1’s) into analog form for transmission across the channel. At the destination, the received analog signal is converted to digital data via demodulation. This is a simplified explanation of how a modem works, and there are other issues that require attention; such as channel impairments, encryption, error detection/correction, data compression, modulation, handshake negotiation, and echo cancellation. These features will be discussed a bit later.
Modulation demodulation assignment
The document discusses modems and their functions. It begins by defining a modem as a device that modulates and demodulates signals to allow computers to communicate over telephone lines. It then describes the main components of a modem:
1. Modulation: The process of varying a carrier signal to encode digital data for transmission.
2. Demodulation: The process of extracting the original digital data from the received modulated carrier signal.
3. Analog to digital and digital to analog conversion: Processes that allow analog signals to be transmitted over phone lines by converting between analog and digital formats.
The document goes on to discuss different types of modulation, demodulation, and conversion techniques in more detail.
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This document discusses wireless networking technologies including IEEE 802.11 (Wi-Fi), Bluetooth, and their standards and specifications. It describes the basic concepts of wireless LANs including connecting devices, medium access control, basic service sets, extended service sets, frame formats, and addressing mechanisms. It also discusses Bluetooth standards, layers, and topologies such as piconets and scatternets.
Introduction to Wireless Communication
Introduction to basics of wireless networks such as
• Radio waves & wireless signal encoding techniques
• Wireless networking issues & constraints
• Wireless internetworking devices
Microwave Transmission
Microwave technology can be used for LANs, extended LANs, and mobile computing. It uses either terrestrial (ground-based) links or satellite links. There are three forms of mobile computing: packet-radio networking, cellular networking, and satellite station networking. Terrestrial microwave links employ line-of-sight transmitters and receivers in the low gigahertz range, requiring stations every 30 miles, while satellite links use geosynchronous satellites to relay signals over long distances. Microwave systems offer advantages like no cables and wide bandwidth but have disadvantages like disruption from obstacles and signal absorption.
Cdma2000
The document discusses CDMA2000, a 3G cellular technology that provides an evolutionary upgrade path from 2G CDMA. It spreads signals across 1.25MHz of spectrum to transmit uniquely encoded signals simultaneously. CDMA2000 supports high-speed packet data through standards like 1X EV-DO that enable up to 2.4Mbps speeds. While it offers advantages like efficient spectrum use and support for advanced services, disadvantages include potential channel pollution from multiple signals and limited international roaming without multimode devices.
WIRELESS TRANSMISSION
Wireless communication is the transfer of information between two or more points that are not connected by an electrical conductor.
The most common wireless technologies use radio
Presentation on DSL & ADSL
The document presents information about Digital Subscriber Line (DSL) technology. It discusses the history of internet access through phone lines and the development of DSL as a way to provide faster internet speeds over existing phone infrastructure. It provides an overview of DSL and Asymmetric DSL (ADSL), how they work, their requirements and limitations. It also briefly discusses other DSL technologies like High-bit-rate DSL, Symmetric DSL and Very High bit-rate DSL.
ASk,FSK,PSK
1. Digital modulation techniques are used to modulate digital information so that it can be transmitted via different mediums. Common digital modulation methods include binary amplitude shift keying (ASK), frequency shift keying (FSK), and phase shift keying (PSK).
2. FSK conveys information by changing the instantaneous frequency of a carrier wave. It is less susceptible to errors than ASK but has a larger spectrum bandwidth. PSK varies the phase of the transmitted signal. BPSK uses two phases while QPSK uses four phases.
3. The performance of digital modulation techniques can be compared using the energy per bit to noise power spectral density ratio (Eb/N0). Lower Eb/N0 values
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This document discusses wireless local area networks (WLANs). It begins by defining WLANs and tracing their history from early developments in the 1970s. The document then lists key advantages of WLANs like installation flexibility, reduced costs, and mobility. Potential disadvantages are also outlined, such as higher costs compared to wired networks and limitations from environmental factors. The document goes on to describe different types of WLAN configurations including infrastructure, peer-to-peer, bridge, and wireless distribution systems. Finally, practical uses of WLANs in corporate, education, finance, and healthcare settings are highlighted.
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ppt on WIFI
This document summarizes the key aspects of routers and Wi-Fi technology. It explains that routers are networking devices that forward data packets between computer networks by reading information in the packets to determine the ultimate destination. It then describes that Wi-Fi uses radio frequency to transmit data wirelessly as an alternative to wired technology. Finally, it outlines some of the advantages of Wi-Fi including no wires, fast deployment and ease of installation, while also noting disadvantages such as slower speeds, limited range, and data security risks compared to wired connections.
Wireless local loop
This document defines and compares two types of wireless local loop (WLL) technologies: Local Multipoint Distribution Service (LMDS) and Multichannel Multipoint Distribution Service (MMDS). LMDS operates above 20 GHz and provides high-speed broadband, while MMDS operates between 2.1-2.7 GHz and provides lower bandwidth but stronger signals over longer distances. Both can provide voice, data and video services as alternatives to wired local loops. Key differences are that LMDS supports higher data rates over shorter ranges while MMDS has a larger cell size and is more suitable for large networks.
wired and wireless networks
This document discusses and compares wired and wireless networks. Wired networks transmit data through physical cables connecting devices, while wireless networks transmit data through the air using electromagnetic waves without cables. Examples of wired networks include telephone lines, cable TV, and fiber optic networks, while wireless technologies include radio frequencies, infrared, Bluetooth, Wi-Fi, and satellite communication.
Cellular Telephone Systems
Today's cellular telephone systems operate by dividing geographic areas into cells served by base stations. Each cell is assigned certain radio frequencies that are reused in non-neighboring cells to increase coverage and capacity. When a mobile user moves between cells, the call is handed off from one base station to another through a mobile switching center to avoid disconnection. Modern cellular networks use digital technologies like CDMA, TDMA and FDMA to provide voice, text, and data services to users through cellular infrastructure.
Transmission media
This document discusses different types of transmission media used for data communication. It describes guided media like twisted pair wires, coaxial cables, and optical fibers. It also covers wireless or unguided media such as terrestrial microwave, satellite microwave, broadcast radio, and infrared. For each medium, it provides details on characteristics, advantages, disadvantages, and applications. The key factors that affect the quality of a transmission medium are its bandwidth, interference levels, and transmission impairments. Optical fiber has the highest bandwidth capacity but was initially more expensive over short distances.
Analog and Digital Transmission
Achyut S.Godbole, “ Data Communications and Networks”, Tata McGraw-Hill Publishing Company Limited, Ninth reprint, 2007
Digital communication systems
The document discusses digital communication systems and outlines topics that will be covered, including digital data communication, multiplexing techniques, digital modulation and demodulation, and performance comparisons of modulation schemes. The objectives are to provide an overview of communication systems and concepts, discuss digital transmission methods and modulation types, and enable students to design simple communication systems and discuss industry trends.
Presentation
- Modems allow computers to transmit digital data over analog telephone lines by modulating and demodulating digital signals. They convert digital signals to audio tones that can be transmitted and received by telephone networks.
- There are three main types of modems: external modems connected via cable, internal modems installed inside computers, and PC Card modems that fit into slots on portable computers.
- When connecting, one modem modulates digital data into audio tones to send over phone lines, while the receiving modem demodulates the tones back into digital data for the receiving computer. Checksums ensure accurate data transmission.
GSM Technology
What is GSM?
The Global System for Mobile communications is a digital cellular communications system. It was developed in order to create a common European mobile telephone standard but it has been rapidly accepted worldwide.
Formerly it was “Groupe Spéciale Mobile” (founded in 1982)
now: Global System for Mobile Communication.
Services:
Tele-services
Bearer or Data Services
Supplementary services
Applications:
Mobile telephony
GSM-R
Telemetry System
- Fleet management
- Automatic meter reading
- Toll Collection
- Remote control and fault reporting of DG sets
Value Added Services
Advantages:
Better Quality of speech
Data transmission is supported
New services offered due to ISDN compatibility
International Roaming possible
Large market
Crisper, cleaner quieter calls
disadvantages:
Dropped and missed calls
Less Efficiency
Security Issues
conclusion
The mobile telephony industry rapidly growing and that has become backbone for business success and efficiency and a part of modern lifestyles all over the world.
In this session I have tried to give and over view of the GSM system. I hope that I gave the general flavor of GSM and the philosophy behind its design.
The GSM is standard that insures interoperability without stifling competition and innovation among the suppliers to the benefit of the public both in terms of cost and service quality.
ISDN Integrated Services Digital Network
Developed by ITU-T, ISDN is a set of protocols that combines digital telephony and data transport services to digitise the telephone network to permit the transmission of audio, video and text over existing telephone line. ISDN is an effort to standardise subscriber services, provide user or network interface and facilitate the inter-networking capabilities of existing voice and data networks. The goal of ISDN is to form a wide area network that provides universal end-to-end connectivity over digital media by integrating separate transmission services into one without adding new links or subscriber links.
Presentation on data communication
The document is a presentation submitted by Harpreet Kaur on data communications. It contains information on various topics related to data communications including an introduction to data communication, components of data communication such as sender, receiver, message, transmission medium and protocol. It also discusses data flow modes, analog and digital signals, types of transmission media including guided media such as coaxial cable, twisted pair cable and fiber optic cable, and unguided media. Finally, it covers networking devices such as modem, hub, switch and router.
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A modem modulates outgoing digital signals from a computer or other digital device to analog signals for a conventional copper twisted pair telephone line and demodulates the incoming analog signal and converts it to a digital signal for the digital device.
The word modem is an acronym for modulator-demodulator. Basically, a modem is used for transmitting and receiving data over a communication channel, such as twisted-pair telephone lines, coaxial cables, and optical fibers. Currently the purpose of a modem is to convert a computer’s data stream to analog format so that it can be transmitted over the analog telephone line.
At the source, modulation techniques are used to convert digital
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The document discusses modems and their functions. It begins by defining a modem as a device that modulates and demodulates signals to allow computers to communicate over telephone lines. It then describes the main components of a modem:
1. Modulation: The process of varying a carrier signal to encode digital data for transmission.
2. Demodulation: The process of extracting the original digital data from the received modulated carrier signal.
3. Analog to digital and digital to analog conversion: Processes that allow analog signals to be transmitted over phone lines by converting between analog and digital formats.
The document goes on to discuss different types of modulation, demodulation, and conversion techniques in more detail.
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The document discusses modems, including their functions, components, types, features, standards, and installation. Specifically:
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A computer network connects multiple computers to enable information sharing. It has three main objectives: sharing resources, information, and processing load. A network requires a sender, medium, and receiver to transmit data. There are three modes of data transmission - simplex, half duplex, and full duplex. Data transmission speed is measured in baud and depends on the medium used such as twisted pair wire, coaxial cable, microwave, satellite, or optical fiber. Common transmission services are dial-up, leased line, ISDN, and VAN.
Group11
This document discusses circuit-switched digital technology and related concepts:
ISDN is a digital communication network that integrates telephone, fax, and data by digitalizing existing telephone networks connected via modem. A LAN is a local network that allows information exchange and communication between equipment in a limited region. Central office switches establish temporary connections between subscribers in a public switched telephone network. A modem modulates and demodulates analog signals to encode and decode digital data for transmission over various means including radio.
BSNL Industrial Training
This is the presentation I gave during the Final year of Engineering.
It is short and concise.
I hope it Helps you all..
Presentation1
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Overview of Modem
- 1. Prepared by: Kishan N. Patel
- 2. INTRODUCTION HISTORY TYPES OF MODEM FUNCTION OF MODEM WHY USE MODEM? TYPES OF MODEM BASED ON SPEED OF DATA TRANSMISION ROLE OF MODEM MODULATION TECHNIQUES ADVANTAGES AND DISADVANTAGES OF MODEM CONCLUSION
- 3. Modem is a communication device that converts binary signal into analog signals for transmission over telephone lines and converts these analog signals back into binary form at the receiving end. Conversion to analog signal is known as modulation. conversion back to binary signal is known as demodulation.
- 4. Modems developed from the need to transmit data for North American air defence during the 1950s. Robert Lucky invented the automatic adaptive equalizer in 1965 at Bell Laboratories. In 1962, the first commercial modem was manufactured - the Bell 103 by AT&T. The 56K modem was invented by Dr. Brent Townshend in 1996.
- 5. Modem can be a several types and they are categorized in a number of ways: 1. Directional capability : Half and full duplex modem 2. Connection to the telephone Line:2 or 4 wire modem 3. Transmission mode: Asynchronous or synchronous modem
- 6. .
- 7. Data Compression Error Correction Flow Control
- 8. Function to be perform at transmitting end: 1. Take the data from RS-232 interface. 2. Convert the data (0s and 1s) into appropriate analog signal. 3. Perform the line control and signaling to other end of phone line. 4. Send the dialing signal if modem is design to dial without presence of user. 5. Have protection against the line overload and other problem.
- 9. Function to be perform at receiving end: 1. Receiving the analog signal and demodulate them into 1s and 0s form. 2. Put the demodulate into RS-232 format connect to RS-232 interface. 3. Perform the line signaling and control. 4. Have protection against the overload problem. 5. Recover the data with minimum numbers of errors from the receiving signal corrupted by noise.
- 10. A MO(dulator) DEM(odultor) is a device that translates an analog signal to digital and back. We use them to take patters of zeros and ones and turn them in to analog electrical signals so they can be sent along a wire, and then translated back to zeros and ones on the other end.
- 11. Low speed modem : They are design to transfer the data with signaling rate up to 300 or 600 bauds. Fsk modulation techniques is used. Medium speed modem : They are design to transfer the data with signaling rate up to 1200 to 4800 baud. BPSK,DPSK techniques is used. .
- 12. High speed modem : They are design to transfer the data with signaling rate up to 19.6kbaud. PSK modulation techniques are used.
- 13. The normal digital signal cannot be put directly on the telephone line. The role of modem is to convert the analog signal to digital signal and digital signal to analog signal. A modem contains a modulator as well as a demodulator. Modulator will convert digital signal to analog signal and Demodulator will convert the analog signal to digital signal .
- 14. The basic modulation techniques used by modem to convert digital data to analog signal : 1. Amplitude shift key (ASK) 2. Frequency shift key (FSK) 3. Phase shift key (PSK) Modem is always used in pairs. Any system whether half or full duplex require a modem at transmitting as well as receiving end.
- 15. More useful in connecting LAN with the Internet Speed depends on the cost modem is probably the most widely used data communication roadway.
- 16. Slow speed when compared to hub. Acts just as a interface between LAN and Internet No traffic maintenance is present main disadvantage of modem is speed. if although if you spend more money you get more speed. but that shouldn't be expectable.
- 17. Niniejszym NETGEAR, Modem connection , Andrew S.Tanenbaum ,Pearson addition Titles by Behrouz A. Forouzan on Data Communications and Networking , edition