This document contains a syllabus for a Communication Electronics course. The syllabus covers 6 units:
1) Amplitude Modulation
2) Angle Modulation
3) Pulse Modulation
4) Noise
5) AM and FM Receivers
6) Broadband Communication Links and Multiplexing
The syllabus provides an overview of the key topics that will be covered in each unit, including the concepts, mathematical analysis, generation methods, and applications of various modulation techniques. It also lists recommended textbooks and reference books for the course.
In this presentation, we tried our best to explain the two basic types of Modulation that are Amplitude modulation and Frequency modulation. We hope you find this PPT useful.
Amplitude modulation (AM) is a modulation technique used for transmitting information via a radio carrier wave. In AM, the amplitude of the carrier wave is varied in proportion to the waveform being transmitted, such as sounds or television pixels. AM has a wider coverage area than FM due to atmospheric propagation. It also allows for long distance propagation because of its wavelength. However, AM signals are not as strong as FM when propagating to obstacles, and only one sideband of the AM signal transmits information, losing power in the other sideband and carrier. Additionally, noise mixes with the AM signal through propagation, making it more difficult to recover the original signal at the receiver. AM is used in radio frequency transmissions.
Amplitude modulation (AM) is a modulation technique that encodes information like an audio signal onto a carrier wave by varying the amplitude of the carrier wave. The key aspects of AM include the modulation index which determines the variation of the carrier amplitude, double sideband transmission where the modulated signal has components at the sum and difference frequencies of the carrier and modulating signals, and envelope detection receivers which recover the audio signal by detecting the envelope of the AM signal. Practical AM systems are implemented using circuits like RF amplifiers, mixers, filters and audio amplifiers in both transmitters and receivers.
Wireless LANs (WLANs) allow computers to connect to a local network using radio transmissions rather than wires. They use technologies like Wi-Fi that transmit data over the 2.4 GHz or 5 GHz radio bands. WLANs provide mobility within a limited range and can be used to avoid installing network cables. However, they have less range than wired networks and can experience interference from other devices.
This document discusses amplitude modulation (AM) and detection. It begins by introducing AM, including its use of a carrier signal to transmit a baseband message signal. It describes how AM varies the amplitude of the carrier based on the message signal. The document then discusses envelope detection used at the receiver to recover the original message signal. It also introduces double sideband suppressed carrier AM, which removes the carrier component to increase power efficiency, requiring a product detector instead of envelope detection.
The document discusses various topics in communication engineering including analog modulation techniques. Unit I covers analog modulation techniques such as amplitude modulation (AM), double sideband suppressed carrier (DSBSC), single sideband suppressed carrier (SSBSC), vestigial sideband (VSB) including their power spectral densities, modulators, and demodulators. It also discusses angle modulation techniques such as phase modulation (PM) and frequency modulation (FM) along with their modulators and demodulators.
This document outlines a lesson plan for a physics class on principles of communication. It introduces communication systems and their components such as transmitters, receivers, and modulators. It discusses topics like amplitude modulation (AM) and frequency modulation (FM), explaining why modulation is necessary to transmit audio frequency signals over long distances. The lesson plan provides objectives, outlines the material to be covered, and assigns homework questions for students.
In this presentation, we tried our best to explain the two basic types of Modulation that are Amplitude modulation and Frequency modulation. We hope you find this PPT useful.
Amplitude modulation (AM) is a modulation technique used for transmitting information via a radio carrier wave. In AM, the amplitude of the carrier wave is varied in proportion to the waveform being transmitted, such as sounds or television pixels. AM has a wider coverage area than FM due to atmospheric propagation. It also allows for long distance propagation because of its wavelength. However, AM signals are not as strong as FM when propagating to obstacles, and only one sideband of the AM signal transmits information, losing power in the other sideband and carrier. Additionally, noise mixes with the AM signal through propagation, making it more difficult to recover the original signal at the receiver. AM is used in radio frequency transmissions.
Amplitude modulation (AM) is a modulation technique that encodes information like an audio signal onto a carrier wave by varying the amplitude of the carrier wave. The key aspects of AM include the modulation index which determines the variation of the carrier amplitude, double sideband transmission where the modulated signal has components at the sum and difference frequencies of the carrier and modulating signals, and envelope detection receivers which recover the audio signal by detecting the envelope of the AM signal. Practical AM systems are implemented using circuits like RF amplifiers, mixers, filters and audio amplifiers in both transmitters and receivers.
Wireless LANs (WLANs) allow computers to connect to a local network using radio transmissions rather than wires. They use technologies like Wi-Fi that transmit data over the 2.4 GHz or 5 GHz radio bands. WLANs provide mobility within a limited range and can be used to avoid installing network cables. However, they have less range than wired networks and can experience interference from other devices.
This document discusses amplitude modulation (AM) and detection. It begins by introducing AM, including its use of a carrier signal to transmit a baseband message signal. It describes how AM varies the amplitude of the carrier based on the message signal. The document then discusses envelope detection used at the receiver to recover the original message signal. It also introduces double sideband suppressed carrier AM, which removes the carrier component to increase power efficiency, requiring a product detector instead of envelope detection.
The document discusses various topics in communication engineering including analog modulation techniques. Unit I covers analog modulation techniques such as amplitude modulation (AM), double sideband suppressed carrier (DSBSC), single sideband suppressed carrier (SSBSC), vestigial sideband (VSB) including their power spectral densities, modulators, and demodulators. It also discusses angle modulation techniques such as phase modulation (PM) and frequency modulation (FM) along with their modulators and demodulators.
This document outlines a lesson plan for a physics class on principles of communication. It introduces communication systems and their components such as transmitters, receivers, and modulators. It discusses topics like amplitude modulation (AM) and frequency modulation (FM), explaining why modulation is necessary to transmit audio frequency signals over long distances. The lesson plan provides objectives, outlines the material to be covered, and assigns homework questions for students.
In telecommunication, a communications system is a collection of individual communications networks, transmission systems, relay stations, tributary stations, and data terminal equipment (DTE) usually capable of interconnection and interoperation to form an integrated whole. The components of a communications system serve a common purpose, are technically compatible, use common procedures, respond to controls, and operate in union. Telecommunications is a method of communication (e.g., for sports broadcasting, mass media, journalism, etc.). A communications subsystem is a functional unit or operational assembly that is smaller than the larger assembly under consideration.
This document provides information about a telecommunication principles course offered at The People's University. The 18-week course covers topics like communication systems, digital communication principles, radio frequency systems, and computer networks. It includes 5 units, each with assignments. Students will complete 3 timed assessments (TMAs), a lab report, and a final exam. Tutorial sessions are also provided to help with course content and assignments. The document outlines the course structure, assessment details, self-study guidelines, and information on getting academic support from tutors.
Electronics and Communication Engineering : Communications, THE GATE ACADEMYklirantga
THE GATE ACADEMY's GATE Correspondence Materials consist of complete GATE syllabus in the form of booklets with theory, solved examples, model tests, formulae and questions in various levels of difficulty in all the topics of the syllabus. The material is designed in such a way that it has proven to be an ideal material in-terms of an accurate and efficient preparation for GATE.
Quick Refresher Guide : is especially developed for the students, for their quick revision of concepts preparing for GATE examination. Also get 1 All India Mock Tests with results including Rank,Percentile,detailed performance analysis and with video solutions
GATE QUESTION BANK : is a topic-wise and subject wise collection of previous year GATE questions ( 2001 – 2013). Also get 1 All India Mock Tests with results including Rank,Percentile,detailed performance analysis and with video solutions
Bangalore Head Office:
THE GATE ACADEMY
# 74, Keshava Krupa(Third floor), 30th Cross,
10th Main, Jayanagar 4th block, Bangalore- 560011
E-Mail: info@thegateacademy.com
Ph: 080-61766222
This document discusses amplitude modulation (AM), which is the simplest form of modulation. AM involves changing the amplitude of a carrier signal based on the amplitude of a modulating signal. The coefficient of modulation expresses the ratio between the amplitudes of the modulating and carrier signals. Power in an AM transmitter is calculated using a formula that involves the power of the carrier and sidebands. A benefit of AM is that it can shift the spectral content of a message signal to a frequency band better suited for the transmission channel.
AM – Frequency spectrum – vector representation – power relations – generation of AM – DSB, DSB/SC, SSB, VSB AM Transmitter & Receiver; FM and PM – frequency spectrum – power relations : NBFM & WBFM, Generation of FM and DM, Armstrong method & Reactance modulations : FM & PM frequency.
The document discusses various types of analog modulation techniques. It begins by defining analog modulation and describing the key components - the message signal, carrier signal, and modulated signal. It then covers amplitude modulation techniques like AM, DSB-SC, and SSB which vary the amplitude of the carrier signal. Key aspects like bandwidth, power distribution, and detection methods are explained for each technique. The document also touches on angle modulation like FM and discusses metrics for evaluating different modulation schemes.
This document discusses different types of analog modulation techniques used in wireless communication, including amplitude modulation (AM), frequency modulation (FM), and phase modulation (PM). It provides details on how each works, their advantages and disadvantages, and examples of applications. AM varies the amplitude of the carrier signal, is simple but susceptible to noise. FM varies the frequency, has better noise immunity than AM. PM varies the phase and is used for satellite communication, though it has a more complex circuitry than AM and FM.
This document provides an overview of EEE 330 Introduction to Communication Systems. It outlines the course components including lectures, exams, and grading. The objectives are to understand telecommunication systems, components such as modulation and multiplexing, and analog and digital communications. Key topics covered include definitions of communication, fundamental communication steps, primary communication resources, and examples of communication systems.
This document provides an overview of analog modulation techniques. It discusses the basic concepts of signals, modulation, and communication systems. It covers various analog modulation schemes including amplitude modulation (AM) and angle modulation. AM techniques described include double sideband with carrier (DSB-FC), double sideband suppressed carrier (DSB-SC), single sideband with carrier (SSB-C), and single sideband suppressed carrier (SSB-SC). Modulation index, generation of AM signals using balanced and ring modulators, and AM demodulation are also covered. Angle modulation techniques of frequency modulation (FM) and phase modulation (PM) are introduced along with their advantages.
Electronics and Communication Engineering : Analog circuits, THE GATE ACADEMYklirantga
THE GATE ACADEMY's GATE Correspondence Materials consist of complete GATE syllabus in the form of booklets with theory, solved examples, model tests, formulae and questions in various levels of difficulty in all the topics of the syllabus. The material is designed in such a way that it has proven to be an ideal material in-terms of an accurate and efficient preparation for GATE.
Quick Refresher Guide : is especially developed for the students, for their quick revision of concepts preparing for GATE examination. Also get 1 All India Mock Tests with results including Rank,Percentile,detailed performance analysis and with video solutions
GATE QUESTION BANK : is a topic-wise and subject wise collection of previous year GATE questions ( 2001 – 2013). Also get 1 All India Mock Tests with results including Rank,Percentile,detailed performance analysis and with video solutions
Bangalore Head Office:
THE GATE ACADEMY
# 74, Keshava Krupa(Third floor), 30th Cross,
10th Main, Jayanagar 4th block, Bangalore- 560011
E-Mail: info@thegateacademy.com
Ph: 080-61766222
This document discusses beamforming and the eight transmission modes in LTE Release 9. It begins with introductions to MIMO technology and beamforming basics. It then explains the eight transmission modes, including single transmit antenna mode, transmit diversity, open and closed loop spatial multiplexing, multi-user MIMO, and two beamforming modes that use UE-specific reference signals. Key aspects of LTE such as physical channels and the reference signal structure are also summarized.
Questions about Understanding benefits of mimo technology (article)Yaseen
MIMO (multiple-input multiple-output) technology uses multiple antennas at both the transmitter and receiver to enhance wireless throughput and performance. It achieves higher data rates than traditional single antenna SISO systems by utilizing the spatial dimension of the wireless channel. MIMO works by using knowledge of the communications channel gained from multiple signal paths to transmit independent data streams from each transmitter antenna. This allows the receiver to recover independent streams and achieve throughput close to double that of SISO for a 2x2 MIMO system. Key challenges for MIMO implementation include antenna design to address multiple antennas, multi-channel synchronization across transceivers, and more sophisticated digital signal processing algorithms.
This document provides information about amplitude modulation (AM) including:
1. AM is a type of modulation where the amplitude of the carrier signal is varied in accordance with the information bearing signal. The envelope of the AM signal contains the information.
2. There are three main types of AM: double sideband full carrier, double sideband suppressed carrier, and single sideband suppressed carrier.
3. Only a small portion (33%) of the total transmitted power in an AM signal is contained in the sidebands, which carry the information. The carrier power remains constant but does not contain information.
This document provides an overview of a communication systems course taught by Ass. Prof. Ibrar Ullah. The course objectives are to develop basic concepts of communication systems using the textbook "Modern Digital And Analog Communication Systems". Students will be evaluated based on homework, tests, quizzes, and a final exam. Key topics covered include analog versus digital communication, modulation techniques, and the relationship between signal-to-noise ratio, channel bandwidth, and rate of communication.
The document provides information about a communications systems course, including:
- The lecturer's contact information and grading breakdown
- An outline of the topics to be covered in each of the 16 weeks including transmission media, wireless communication, and mobile networks
- Expectations that students can interrupt with questions, should try to solve problems themselves before asking for help, and should review notes after class
- An index of subtopics to be discussed like historical background, communication system components, analog and digital systems, and important communication systems.
Unit 4 process signal modlation and demodulation techniqueshiya123jes
This document discusses various modulation and demodulation techniques. It begins by defining modulation as combining a low frequency signal with a high frequency carrier wave. It then describes different types of modulation including: amplitude modulation (AM), frequency modulation (FM), phase modulation (PM), pulse amplitude modulation (PAM), pulse width modulation (PWM), and pulse position modulation (PPM). It also discusses digital modulation techniques like pulse code modulation (PCM). For each technique, it provides the mathematical equations and diagrams to illustrate how the modulation works and compares their advantages and disadvantages. The document concludes by stating that demodulation is the reverse process of extracting the original information signal from the modulated carrier wave.
This document discusses power considerations in double sideband amplitude modulation (DSBAM) radio transmission. It provides two equations for calculating total power in a DSBAM signal based on carrier power and power in the upper and lower sidebands. On average, only about 2.15% of total transmitted power is "useful" information power, with over 95.7% being carrier power. Even at maximum modulation, only 16.7% of power is information-carrying. The document uses an example of a portable DSBAM transmitter requiring 10W per sideband. It calculates it would need a large, 39-amp battery. By removing one sideband and carrier via filtering, the same information could be transmitted with only 10
3GPP is going to finalize the 5G standard by 2018. 5G is scheduled to launch in around early 2020s. Even if it is not determined yet regarding the standard technology details, many researchers expect that 5G will transfer 1000 times more data, and thus, can connect billions of IoT (Internet of Things) devices at the same time. Massive MIMO (multiple input and multiple output) is one of the key candidate technologies that enable 5G to support IoT devices connection. Massive MIMO (MaMi) technology can address the high capacity requirement demanded by 5G exploiting many antennas both in the transmitter and the receiver.
This document outlines and describes space-time coding techniques for MIMO wireless systems. It introduces MIMO system models and derives MIMO capacity. It then discusses space-time coding performance analysis, including diversity-multiplexing tradeoffs and error analysis. Finally, it describes specific space-time coding schemes, including Alamouti codes, space-time block codes, and space-time trellis codes.
1) Modulation involves changing characteristics of a high-frequency carrier signal according to an information signal. This allows signal transmission over long distances and multiple signals over the same channel.
2) The main modulation types are amplitude modulation (AM), which changes amplitude; frequency modulation (FM), which changes frequency; and phase modulation (PM), which changes phase.
3) AM is the simplest form and varies the carrier amplitude by the information signal. It has advantages of simplicity but is inefficient in power and bandwidth usage, and susceptible to noise.
The document discusses analog communications and the Analog Communications course at Matrusri Engineering College. It includes:
- Course objectives like analyzing analog communication systems, understanding generation and detection of analog modulation techniques, and analyzing noise performance.
- Course outcomes like describing modulation/demodulation schemes and comparing analog modulation schemes.
- A syllabus covering topics like linear modulation schemes, angle modulation schemes, analog pulse modulation schemes, transmitters and receivers, and noise sources and types.
- Details of the course include lesson plans with topics, outcomes, textbooks, and introductions to modules on concepts like amplitude modulation and its time/frequency domain representations.
In telecommunication, a communications system is a collection of individual communications networks, transmission systems, relay stations, tributary stations, and data terminal equipment (DTE) usually capable of interconnection and interoperation to form an integrated whole. The components of a communications system serve a common purpose, are technically compatible, use common procedures, respond to controls, and operate in union. Telecommunications is a method of communication (e.g., for sports broadcasting, mass media, journalism, etc.). A communications subsystem is a functional unit or operational assembly that is smaller than the larger assembly under consideration.
This document provides information about a telecommunication principles course offered at The People's University. The 18-week course covers topics like communication systems, digital communication principles, radio frequency systems, and computer networks. It includes 5 units, each with assignments. Students will complete 3 timed assessments (TMAs), a lab report, and a final exam. Tutorial sessions are also provided to help with course content and assignments. The document outlines the course structure, assessment details, self-study guidelines, and information on getting academic support from tutors.
Electronics and Communication Engineering : Communications, THE GATE ACADEMYklirantga
THE GATE ACADEMY's GATE Correspondence Materials consist of complete GATE syllabus in the form of booklets with theory, solved examples, model tests, formulae and questions in various levels of difficulty in all the topics of the syllabus. The material is designed in such a way that it has proven to be an ideal material in-terms of an accurate and efficient preparation for GATE.
Quick Refresher Guide : is especially developed for the students, for their quick revision of concepts preparing for GATE examination. Also get 1 All India Mock Tests with results including Rank,Percentile,detailed performance analysis and with video solutions
GATE QUESTION BANK : is a topic-wise and subject wise collection of previous year GATE questions ( 2001 – 2013). Also get 1 All India Mock Tests with results including Rank,Percentile,detailed performance analysis and with video solutions
Bangalore Head Office:
THE GATE ACADEMY
# 74, Keshava Krupa(Third floor), 30th Cross,
10th Main, Jayanagar 4th block, Bangalore- 560011
E-Mail: info@thegateacademy.com
Ph: 080-61766222
This document discusses amplitude modulation (AM), which is the simplest form of modulation. AM involves changing the amplitude of a carrier signal based on the amplitude of a modulating signal. The coefficient of modulation expresses the ratio between the amplitudes of the modulating and carrier signals. Power in an AM transmitter is calculated using a formula that involves the power of the carrier and sidebands. A benefit of AM is that it can shift the spectral content of a message signal to a frequency band better suited for the transmission channel.
AM – Frequency spectrum – vector representation – power relations – generation of AM – DSB, DSB/SC, SSB, VSB AM Transmitter & Receiver; FM and PM – frequency spectrum – power relations : NBFM & WBFM, Generation of FM and DM, Armstrong method & Reactance modulations : FM & PM frequency.
The document discusses various types of analog modulation techniques. It begins by defining analog modulation and describing the key components - the message signal, carrier signal, and modulated signal. It then covers amplitude modulation techniques like AM, DSB-SC, and SSB which vary the amplitude of the carrier signal. Key aspects like bandwidth, power distribution, and detection methods are explained for each technique. The document also touches on angle modulation like FM and discusses metrics for evaluating different modulation schemes.
This document discusses different types of analog modulation techniques used in wireless communication, including amplitude modulation (AM), frequency modulation (FM), and phase modulation (PM). It provides details on how each works, their advantages and disadvantages, and examples of applications. AM varies the amplitude of the carrier signal, is simple but susceptible to noise. FM varies the frequency, has better noise immunity than AM. PM varies the phase and is used for satellite communication, though it has a more complex circuitry than AM and FM.
This document provides an overview of EEE 330 Introduction to Communication Systems. It outlines the course components including lectures, exams, and grading. The objectives are to understand telecommunication systems, components such as modulation and multiplexing, and analog and digital communications. Key topics covered include definitions of communication, fundamental communication steps, primary communication resources, and examples of communication systems.
This document provides an overview of analog modulation techniques. It discusses the basic concepts of signals, modulation, and communication systems. It covers various analog modulation schemes including amplitude modulation (AM) and angle modulation. AM techniques described include double sideband with carrier (DSB-FC), double sideband suppressed carrier (DSB-SC), single sideband with carrier (SSB-C), and single sideband suppressed carrier (SSB-SC). Modulation index, generation of AM signals using balanced and ring modulators, and AM demodulation are also covered. Angle modulation techniques of frequency modulation (FM) and phase modulation (PM) are introduced along with their advantages.
Electronics and Communication Engineering : Analog circuits, THE GATE ACADEMYklirantga
THE GATE ACADEMY's GATE Correspondence Materials consist of complete GATE syllabus in the form of booklets with theory, solved examples, model tests, formulae and questions in various levels of difficulty in all the topics of the syllabus. The material is designed in such a way that it has proven to be an ideal material in-terms of an accurate and efficient preparation for GATE.
Quick Refresher Guide : is especially developed for the students, for their quick revision of concepts preparing for GATE examination. Also get 1 All India Mock Tests with results including Rank,Percentile,detailed performance analysis and with video solutions
GATE QUESTION BANK : is a topic-wise and subject wise collection of previous year GATE questions ( 2001 – 2013). Also get 1 All India Mock Tests with results including Rank,Percentile,detailed performance analysis and with video solutions
Bangalore Head Office:
THE GATE ACADEMY
# 74, Keshava Krupa(Third floor), 30th Cross,
10th Main, Jayanagar 4th block, Bangalore- 560011
E-Mail: info@thegateacademy.com
Ph: 080-61766222
This document discusses beamforming and the eight transmission modes in LTE Release 9. It begins with introductions to MIMO technology and beamforming basics. It then explains the eight transmission modes, including single transmit antenna mode, transmit diversity, open and closed loop spatial multiplexing, multi-user MIMO, and two beamforming modes that use UE-specific reference signals. Key aspects of LTE such as physical channels and the reference signal structure are also summarized.
Questions about Understanding benefits of mimo technology (article)Yaseen
MIMO (multiple-input multiple-output) technology uses multiple antennas at both the transmitter and receiver to enhance wireless throughput and performance. It achieves higher data rates than traditional single antenna SISO systems by utilizing the spatial dimension of the wireless channel. MIMO works by using knowledge of the communications channel gained from multiple signal paths to transmit independent data streams from each transmitter antenna. This allows the receiver to recover independent streams and achieve throughput close to double that of SISO for a 2x2 MIMO system. Key challenges for MIMO implementation include antenna design to address multiple antennas, multi-channel synchronization across transceivers, and more sophisticated digital signal processing algorithms.
This document provides information about amplitude modulation (AM) including:
1. AM is a type of modulation where the amplitude of the carrier signal is varied in accordance with the information bearing signal. The envelope of the AM signal contains the information.
2. There are three main types of AM: double sideband full carrier, double sideband suppressed carrier, and single sideband suppressed carrier.
3. Only a small portion (33%) of the total transmitted power in an AM signal is contained in the sidebands, which carry the information. The carrier power remains constant but does not contain information.
This document provides an overview of a communication systems course taught by Ass. Prof. Ibrar Ullah. The course objectives are to develop basic concepts of communication systems using the textbook "Modern Digital And Analog Communication Systems". Students will be evaluated based on homework, tests, quizzes, and a final exam. Key topics covered include analog versus digital communication, modulation techniques, and the relationship between signal-to-noise ratio, channel bandwidth, and rate of communication.
The document provides information about a communications systems course, including:
- The lecturer's contact information and grading breakdown
- An outline of the topics to be covered in each of the 16 weeks including transmission media, wireless communication, and mobile networks
- Expectations that students can interrupt with questions, should try to solve problems themselves before asking for help, and should review notes after class
- An index of subtopics to be discussed like historical background, communication system components, analog and digital systems, and important communication systems.
Unit 4 process signal modlation and demodulation techniqueshiya123jes
This document discusses various modulation and demodulation techniques. It begins by defining modulation as combining a low frequency signal with a high frequency carrier wave. It then describes different types of modulation including: amplitude modulation (AM), frequency modulation (FM), phase modulation (PM), pulse amplitude modulation (PAM), pulse width modulation (PWM), and pulse position modulation (PPM). It also discusses digital modulation techniques like pulse code modulation (PCM). For each technique, it provides the mathematical equations and diagrams to illustrate how the modulation works and compares their advantages and disadvantages. The document concludes by stating that demodulation is the reverse process of extracting the original information signal from the modulated carrier wave.
This document discusses power considerations in double sideband amplitude modulation (DSBAM) radio transmission. It provides two equations for calculating total power in a DSBAM signal based on carrier power and power in the upper and lower sidebands. On average, only about 2.15% of total transmitted power is "useful" information power, with over 95.7% being carrier power. Even at maximum modulation, only 16.7% of power is information-carrying. The document uses an example of a portable DSBAM transmitter requiring 10W per sideband. It calculates it would need a large, 39-amp battery. By removing one sideband and carrier via filtering, the same information could be transmitted with only 10
3GPP is going to finalize the 5G standard by 2018. 5G is scheduled to launch in around early 2020s. Even if it is not determined yet regarding the standard technology details, many researchers expect that 5G will transfer 1000 times more data, and thus, can connect billions of IoT (Internet of Things) devices at the same time. Massive MIMO (multiple input and multiple output) is one of the key candidate technologies that enable 5G to support IoT devices connection. Massive MIMO (MaMi) technology can address the high capacity requirement demanded by 5G exploiting many antennas both in the transmitter and the receiver.
This document outlines and describes space-time coding techniques for MIMO wireless systems. It introduces MIMO system models and derives MIMO capacity. It then discusses space-time coding performance analysis, including diversity-multiplexing tradeoffs and error analysis. Finally, it describes specific space-time coding schemes, including Alamouti codes, space-time block codes, and space-time trellis codes.
1) Modulation involves changing characteristics of a high-frequency carrier signal according to an information signal. This allows signal transmission over long distances and multiple signals over the same channel.
2) The main modulation types are amplitude modulation (AM), which changes amplitude; frequency modulation (FM), which changes frequency; and phase modulation (PM), which changes phase.
3) AM is the simplest form and varies the carrier amplitude by the information signal. It has advantages of simplicity but is inefficient in power and bandwidth usage, and susceptible to noise.
The document discusses analog communications and the Analog Communications course at Matrusri Engineering College. It includes:
- Course objectives like analyzing analog communication systems, understanding generation and detection of analog modulation techniques, and analyzing noise performance.
- Course outcomes like describing modulation/demodulation schemes and comparing analog modulation schemes.
- A syllabus covering topics like linear modulation schemes, angle modulation schemes, analog pulse modulation schemes, transmitters and receivers, and noise sources and types.
- Details of the course include lesson plans with topics, outcomes, textbooks, and introductions to modules on concepts like amplitude modulation and its time/frequency domain representations.
This document discusses amplitude modulation (AM) in communications systems. It defines AM as varying the amplitude of a carrier signal in accordance with the instantaneous amplitude of a modulating signal while keeping the carrier frequency and phase unchanged. The time and frequency domain representations of AM waves are presented. Key aspects covered include single tone modulation, power relations in AM waves, generation of AM waves using a switching modulator, and detection of AM waves using an envelope detector.
This is the presentation on the basic concepts of electronics and communication. In this we can get the knowledge of the basic things used in the airport in CNS department.
AM modulation and Demodulation with Circuit and OutputSovan Paul
Here we use IC8038 as a signal generator to generate modulating and carrier signal. IC1496 a Balance Modulator IC used for modulation purpose, for demodulation purpose simple Diode Detector(Envelop type) is used.
This document provides an overview of the Communication Engineering course EC6651. The objectives are to introduce various analog and digital communication methods, source and line coding techniques, and multiple access techniques used in communication systems. The 5 units cover topics like analog communication systems, digital communication, source and line codes/error control, multiple access techniques, and satellite/optical fiber/powerline communications. The course aims to help students understand and analyze linear and digital electronic circuits as applied to communication systems.
1 . introduction to communication systemabhijitjnec
This document provides an introduction to communication systems. It discusses the basic components and elements of a communication system including the input, transmitter, channel, receiver and output. It also covers various modulation techniques used to transmit signals over different types of channels. Finally, it discusses different types of signal propagation including ground waves, sky waves and space waves and how radio frequency spectrum is allocated internationally.
The document discusses analog communication systems and amplitude modulation. It introduces key concepts such as elements of a communication system including the information source, transmitter, channel, and receiver. It describes amplitude modulation where the amplitude of a carrier wave is varied in accordance with the modulating signal. Common modulation techniques like DSB-SC and generation methods like using a square law or switching modulator are summarized. Detection or demodulation of the AM signal using detectors like square law, envelope, and rectifier are also outlined.
Principles of communication systems for referenceNatarajVijapur
This document provides information about the Principles of Communication Systems course offered in the 4th semester by the Department of Electronics and Communication Engineering. It includes details about the course code, modules covered, learning objectives, textbooks, and an introduction to modulation techniques like amplitude modulation and double sideband suppressed carrier modulation. Key concepts discussed are generation of AM waves using a switching modulator, frequency spectrum of AM signals, envelope detection for demodulation, and power savings achieved by suppressing the carrier in DSB-SC systems.
Communication Theory-1 Project || Single Side Band Modulation using Filtering...rameshreddybattini
Communication Theory-1 Project || Single Side Band Modulation using Filtering Method and Synchronous Demodulation in the Presence of Noise || Using Matlab Code
This document provides information about the Analog Communications course offered at Matrusri Engineering College. It includes the course objectives, outcomes, syllabus, lesson plan and introduction. The key points are:
- The course objectives are to analyze analog communication systems and understand various analog modulation techniques, noise performance and AM/FM receivers.
- The syllabus covers topics like linear modulation schemes, angle modulation schemes, transmitters and receivers, noise sources and types, and analog pulse modulation schemes.
- The lesson plan provides details of topics to be covered in each unit, including frequency modulation, phase modulation, and modulation/demodulation techniques.
- The introductions provide an overview of the topics to be discussed in each
This document provides an overview of amplitude modulation and demodulation. It discusses:
1) Modulation is used to shift message signals to specific frequency bands for transmission. Amplitude modulation varies the amplitude of a carrier signal based on the message signal.
2) Demodulation recovers the original message signal by shifting the modulated signal's spectrum back to its original position. This involves multiplying the carrier signal by the received modulated signal and filtering out the unwanted frequencies.
3) Amplitude modulation can be achieved using analog multipliers or nonlinear devices. Nonlinear modulators generate sum and difference frequencies that allow separating the message signal through filtering.
This document summarizes power line carrier communication (PLCC), which is used for communication over medium and long distances in power networks. PLCC uses existing power lines as a communication medium. It provides a more economical and reliable communication method than alternatives like telephone lines or wireless systems. The key components of a PLCC system include transmitters, the power line channel, receivers, carrier signals in the audio frequency range, modulation techniques, and coupling arrangements like capacitors to introduce signals onto power lines. Modern PLCC systems can handle various functions like telemetry, signaling, control, and protection.
This task involves generating a single tone SSB modulated signal. A modulating signal m(t) = cos(1000πt) and carrier c(t) = cos(104πt) are used. The SSB modulated signal is generated using the filtering method. The USB and LSB spectra are identified, with the USB spectrum occupying frequencies above the carrier and the LSB spectrum below. The maximum and minimum envelope amplitudes and power in the USB, LSB and modulated signals are determined. Simulation results and plots of the signals and their spectra are presented.
This document provides an overview of analog communications and amplitude modulation (AM). It discusses the key components of a communication system including the input/output transducers, transmitter, channel, and receiver. For AM, it describes how the input signal is used to vary the amplitude of the carrier signal. It also examines the frequency spectrum of AM signals and discusses different forms of AM including double sideband suppressed carrier modulation. Coherent detection requires synchronization of both frequency and phase between the transmitter and receiver for DSB-SC due to the absence of the carrier signal.
This document discusses various modulation techniques used in analog and digital communication systems. It covers amplitude modulation (AM) theory and its mathematical expression. It also discusses double sideband suppressed carrier modulation (DSB-SC), coherent detection of DSB-SC signals using a local oscillator. Quadrature carrier multiplexing is described which allows transmission of two message signals. Methods for generating single sideband (SSB) signals including filter, phase-shift and Weaver's method are outlined. Vestigial sideband (VSB) modulation motivation, sideband shaping filter and detection are summarized. Generation of VSB uses similar filter or phase discrimination methods as SSB.
The Presentation Video
https://www.youtube.com/watch?v=5GiiIppb2o4&feature=youtu.be
*Contents
1-Challenges in Wireless Communication
2-Multipath andFading
3-MIMO and Diversity
4-Receive Diversity /Maximum ratio combining (MRC)
5-MIMO Evolution
6- Coordinated Multi point (CoMP)
7-Level of Cooperation and Architecture
8-CoMP System Model
Modulation is the process of putting information onto a carrier wave for transmission. It is needed if the medium is bandpass in nature or only a bandpass channel is available. There are three main types of analog modulation: amplitude modulation (AM), frequency modulation (FM), and phase modulation (PM). AM varies the amplitude of the carrier wave, FM varies the frequency, and PM varies the phase. The frequency spectrum of an AM signal contains sidebands above and below the carrier frequency. The bandwidth is twice the modulating signal bandwidth.
This document provides instructions for an experiment on amplitude modulation (AM) using a simple circuit. The experiment aims to generate an AM signal by modulating a carrier wave with a message signal. Students will construct three circuits: 1) a carrier wave generator, 2) a message signal generator, and 3) an AM modulator combining the two signals using a field-effect transistor. The report requires explaining AM theory, describing the experimental setup, and analyzing modulation index results for different frequencies.
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Amplitude modulation (Communication Electronics )
1. Tulsiramji Gaikwad-Patil College of
Engineering & Technology
Wardha Road, Nagpur-441 108
Department of Electronics and
Communication Engineering
B.E. Third Year (V Semester)
Course: BEECE504T: Communication
Electronics
By
Mr. Rahul Dhuture
Assistant Professor
Electronics and Communication Engineering Department
TGPCET, Nagpur.
1
TGPCET/20-21/BEECE504T
2. Syllabus
Unit I: Amplitude (Linear) Modulation MARKS- (08)
• Base band & Carrier communication, Introduction of amplitude modulation, Equation of AM,
• Generation of AM (DSBFC) and its spectrum, Modulation Index , Power relations applied to
sinusoidal signals,
• DSBSC – multiplier modulator, Non linear generation, switching modulator, Ring modulator &
its spectrum,
• SSBSC, ISB & VSB, their generation methods & Comparison, AM Broadcast technical
standards.
Unit II: Angle Modulation MARKS-(12)
• Concept of Angle modulation, Types of Angle Modulation, frequency spectrum, Narrow band
& wide
• band FM, Modulation index, Bandwidth, Phase Modulation, Bessel’s Function and its
mathematical analysis,
• Generation of FM (Direct & Indirect Method), Comparison of FM and PM.
TGPCET/20-21/BEECE504T/U-I 2
3. Unit III: Pulse Modulation MARKS- (10)
• Band limited & time limited signals, Narrowband signals and systems, Sampling theorem in
time
• domain, Nyquist criteria, Types of sampling- ideal, natural, flat top, Aliasing & Aperture effect.
• Pulse Analog modulation: PAM PWM & PPM.
Unit IV: Noise MARKS- (10)
• Sources of Noise, Types of Noise, White Noise, Thermal noise, shot noise, partition noise,
Low
• frequency or flicker noise, burst noise, avalanche noise, Signal to Noise Ratio, SNR of tandem
Connection,
• Noise Figure, Noise Temperature, Friss formula for Noise Figure, Noise Bandwidth.
Unit V: AM and FM Receivers MARKS-(10)
• Communication Receiver, Block Diagram & special Features
• Block diagram of AM and FM Receivers, Super heterodyne Receiver, Performance
characteristics:
• Sensitivity, Selectivity, Fidelity, Image Frequency Rejection, Pre-emphasis, De-emphasis
• AM Detection: Rectifier detection, Envelope detection, Demodulation of DSBSC:
Synchronous detection,
• Demodulation of SSBSC.
• FM Detection: Foster Seelay FM Detector & FM detection using PLL
TGPCET/20-21/BEECE504T/U-I 3
4. Unit VI: Broadband Communication Links & Multiplexing MARKS- (10)
• Multiplexing: Frequency Division Multiplexing, Time Division Multiplexing, Code Division
Multiplexing.
• Short and Medium Haul Systems: Coaxial Cables, Fiber optic links, Microwave Links,
Tropospheric scatter Links.
• Long Haul Systems: Submarine cables.
Books:
• Text Books:
• 1. Kennedy & Devis : Electronic Communication Systems , Tata McGraw Hills
Publication(Fourth Edition)
• 2. Dennis Roddy & Coolen - Electronic Communication, PHI (Fourth Edition)
• 3. B. P. Lathi: Modern Digital and Analog. Communication Systems: Oxford Press Publication
(Third Edition)
• Reference Books:
• 1. Simon Haykin: Communication Systems, John Wiley & Sons (Fourth Edition)
• 2. Taub & Schilling: Principles of Communication Systems, Tata McGraw-Hill
TGPCET/20-21/BEECE504T/U-I 4
8. What is Modulation
• Modulation
In the modulation process, some characteristic of a high-
frequency carrier signal (bandpass), is changed according to the
instantaneous amplitude of the information (baseband) signal.
Why Modulation is used
• Suitable for signal transmission (distance…etc)
• Multiple signals transmitted on the same channel
• Capacitive or inductive devices require high
frequency AC input (carrier) to operate Stability and
noise rejection
TGPCET/20-21/BEECE504T/U-I 8
9. About Modulation….
• Application Examples
• Broadcasting of both audio
and video signals.
• Mobile radio communications, such as cell phone.
• Basic modulation types
–Amplitude Modulation: changes the amplitude.
– Frequency Modulation: changes the frequency.
– Phase Modulation: changes the phase
TGPCET/20-21/BEECE504T/U-I 9
10. Modulation Theory
• A sine wave is represented as follows
c(t)= Ac cos(2πfct)
• Here Ac, fc all represent parameters that can be
modulated in the carrier waveform in order to
carry information.
• The modulation schèmes are known as :
Ac -> Amplitude Modulation
fc -> Frequency Modulation
TGPCET/20-21/BEECE504T/U-I 10
11. Basic Amplitude
Modulation (A.M.)
• Amplitude Modulation is the simplest and earliest
form of transmitters
• The information signal varies the instantaneous
amplitude of the carrier
TGPCET/20-21/BEECE504T/U-I 11
12. Modulation permits the use of
multiplexing
• Multiplexing means allowing simultaneous
communication by multiple users on the same
channel.
• For instance, the radio frequency spectrum must
be shared and modulation allows users to separate
themselves into bands.
TGPCET/20-21/BEECE504T/U-I 12
13. AMPLITUDE MODULATION
(AM)
• In amplitude modulation, the message signal m(t) is
impressed on the amplitude of the carrier signal
c(t) = Ac COS (2∏fct)
• This results in a sinusoidal signal whose amplitude is a
function of the message signal m(t)
• There are several different ways of amplitude
modulating the carrier signal by m(t)
• Each results in different spectral characteristics for the
transmitted signal
TGPCET/20-21/BEECE504T/U-I 13
14. • Mainly these methods are used for AM:
(a) Double Sideband with Large carrier AM
(DSB-LC AM)
(b) Double sideband, suppressed-carrier AM
(DSB-SC AM)
(c) Single-sideband AM (SSB AM)
(d) Vestigial Sideband (VSB) modulation
TGPCET/20-21/BEECE504T/U-I 14
17. Full AM modulation ( DSB-LC)
1 The carrier signal is
Sc (t) = Ac cos(Ꞷc t) where Ꞷ c =2∏fc
2 In the same way, a modulating signal
(information signal) can also be expressed as
Sm ( t)= Am cos (Ꞷ m t)
3 The amplitude-modulated wave can be
expressed as
s(t) =[ Ac + Sm (t)] cos(Ꞷ c t)
TGPCET/20-21/BEECE504T/U-I 17
18. 4. By substitution
s(t)=[Ac + Am COS(Ꞷ m t) ] COS (Ꞷ c t)
5. The modulation index.
m=Am / Ac
6. Therefore The full AM signal may be
written as
S(t) = Ac (1+m COS(Ꞷ m t) ) COS Ꞷ c t
TGPCET/20-21/BEECE504T/U-I 18
19. • By using mathematical formula
COSA COSB = 1/2 [COS(A+B) +COS (A-B)]
Final mathematical expression of AM. wave
TGPCET/20-21/BEECE504T/U-I 19
S(t) = Ac ( COS Ꞷ c t) +
𝒎 𝑨𝒄
𝟐
COS (Ꞷ c + Ꞷ m)t +
𝒎 𝑨𝒄
𝟐
COS (Ꞷ c - Ꞷ m)t
20. Double-Sideband Suppressed-Carrier
AM
A double-sideband, suppressed-carrier (DSB-SC) AM
signal is obtained by multiplying the message signal
m(t) with the carrier signal c(t) = Ac cos (2∏fct)
Amplitude-modulated signal:
u(t) = m(t) * c(t) = Ac m(t) cos(2∏fct)
TGPCET/20-21/BEECE504T/U-I 20
21. • An example of the message signal m(t), the
carrier c(t), and the modulated signal u (t) are
shown in fig in next slide.
• This figure shows that a relatively slowly
varying message signal m(t) is
• changed into a rapidly varying modulated
signal u(t), and due to its rapid changes with
time, it contains higher frequency components
TGPCET/20-21/BEECE504T/U-I 21
23. Single-Sideband AM
• The two sidebands of an AM signal are mirror
images of one another
• As a result, one of the sidebands is redundant
• Using single-sideband suppressed-carrier
transmission results in reduced bandwidth and
therefore twice as many signals may be
transmitted in the same spectrum allotment
TGPCET/20-21/BEECE504T/U-I 23
24. Single-Sideband AM
• A method, illustrated in
Figure, generates a
DSB-SC AM signal and
then employs a filter
that selects either the
upper sideband or the
lower sideband of the
double-sideband AM
signal
v TGPCET/20-21/BEECE504T/U-I 24
Figure : Generation of a singlesideband AM
signal by filtering one of the sidebands
of a DSB-SC AM signal.
25. Advantages/disadvantages
Advantages of Amplitude Modulation, AM
• It is simple to implement and having frequency range from750khz to 1250 khz
• it can be demodulated using a circuit consisting of very few components
• AM receivers are very cheap as no specialized components are needed.
Disadvantages of amplitude modulation
• It is not efficient in terms of its power usage
• It is not efficient in terms of its use of bandwidth, requiring a
bandwidth equal to twice that of the highest audio frequency.
• It is prone to high levels of noise because most noise is amplitude
based and obviously AM detectors are sensitive to it.
TGPCET/20-21/BEECE504T/U-I 25
26. Online Assignment -1
Q.1 What is Communication system and give
the classification of the same.
Q.2 Define and explain with mathematical
expression of the A.M. modulation wave.
TGPCET/20-21/BEECE504T/U-I 26
29. • Angle modulation is the process of varying the frequency and
phase of a carrier wave in proportion to the frequency and
phase of a base band signal. The amplitude of the carrier
remains constant.
• It is of two types
Frequency Modulation
Phase Modulation
Angle Modulation
30. Frequency modulation is the process of varying the frequency
of a carrier wave in proportion to the amplitude of a
baseband signal. The amplitude and phase of the carrier
remains constant.
Frequency Modulation
32. Theoretically, an infinite number of sidebands
produced, but most of power is contained in first
(m+1) sidebands
Thus transmission requires a bandwidth of
approximately 2 (m+1) fm Hz
Frequency Modulation Index
33. Another term common to FM is the modulation index, as
determined by the formula:
Frequency Modulation Index
m
f
f
m
Sideband structure is more complicated than for AM;
many sidebands produced
Complexity depends on m However, spacing between carrier and
sidebands (and between adjacent sidebands) is
equal to fm, just as for AM
34. Another term common to FM is the modulation index, as
determined by the formula:
Frequency Modulation Index
m
f
f
m
Sideband structure is more complicated than for AM;
many sidebands produced
Complexity depends on m However, spacing between carrier and
sidebands (and between adjacent sidebands) is
equal to fm, just as for AM
36. • For FM, the bandwidth varies with both deviation and modulating
frequency
• Increasing modulating frequency reduces modulation index so it reduces
the number of sidebands with significant amplitude
• On the other hand, increasing modulating frequency increases the
frequency separation between sidebands
• Bandwidth increases with modulation frequency but is not directly
proportional to it
Bandwidth
37. • There are no theoretical limits to the modulation index or the
frequency deviation of an FM signal
• The limits are a practical compromise between signal-to-noise
ratio and bandwidth
• Government regulations limit the bandwidth of FM
transmissions in terms of maximum frequency deviation and
the maximum modulation frequency
Narrowband and Wideband FM
40. • The maximum frequency deviation of an FM transmitter is
restricted by law, not by any physical constraint
• Traditional oscilloscope displays are not useful in analyzing FM
signals
• A spectrum analyzer is much more useful in determining the
qualities of an FM signal
FM Measurements
43. Sampling Theorem
Fig 1:Impulse sampling of an analog voltage
A sampler is a mixer with a train of very
narrow pulses as the local oscillator input.
If the analog input is sampled
instantaneously at regular intervals at a
rate that is at least twice the highest
analog frequency
fs > 2fa(max)
then the samples contain all of the
information of the original signal.
44. • The analog signal v(t) has a signal spectrum represented by the Fourier transform
V(f), and the sampling signal
consists of instantaneous impulses every nTs sec, where n = 0, +1, +2, …
• The Fourier transform of s(t) is
Sampling Theorem
s
ns
nff
T
fS
1
n
snTtts
The time-domain product performed by the sampler produces a
sampled output spectrum given by
s
ns
s nffV
T
fV
1
45. • where this spectrum consists of replicas of the analog signal spectrum V(f),
translated in frequency by each of the sampling frequency harmonics
• The sampler is a wideband (harmonic) mixer producing upper and lower
sidebands at each harmonic of the sampling frequency.
• Figure (2a) illustrates the correct way to sample: if sampling is done at fs >
2fA(max) the upper and lower sidebands do not overlap each other,
• and the original information can be recovered by passing the signal
through a low-pass filter (see Figure 2c and d).
Sampling Theorem
46. • A PAM waveform consists of a sequence of flat-topped pulses.
The amplitude of each pulse corresponds to the value of the
message signal x(t) at the leading edge of the pulse.
Pulse Amplitude Modulation
Fig 3: Pulse Amplitude Modulation waveform
47. • The circuit of Figure (4)is used to illustrate pulse amplitude
modulation (PAM). The FET is the switch used as a sampling
gate.
• When the FET is on, the analog voltage is shorted to ground;
when off, the FET is essentially open, so that the analog signal
sample appears at the output.
• Op-amp 1 is a noninverting amplifier that isolates the analog
input channel from the switching function.
Pulse Amplitude Modulation –
Natural and Flat-Top Sampling
48. Demodulation
Figure 10: PPM demodulator
• As illustrated in Figure 10, a narrow clock pulse sets an RS flip-flop output high,
and the next PPM pulses resets the output to zero.
• The resulting signal, PWM, has an average voltage proportional to the time
difference between the PPM pulses and the reference clock pulses.
• Time-averaging (integration) of the output produces the analog variations
49. • PPM has the same disadvantage as continuous analog phase modulation: a
coherent clock reference signal is necessary for demodulation.
• The reference pulses can be transmitted along with the PPM signal.
• This is achieved by full-wave rectifying the PPM pulses of Figure 11-9a, which has
the effect of reversing the polarity of the negative (clock-rate) pulses.
• Then an edge-triggered flipflop (J-K or D-type) can be used to accomplish the same
function as the RS flip-flop of Figure 10 using the clock input.
• The penalty is more pulses/second will require greater bandwidth, and the pulse
width limit the pulse deviations for a given pulse period.
Demodulation
51. • Like PCM, a delta modulation system consists of an encoder and a decoder
• unlike PCM, however, a delta modulator generates single-bit words that represent
the difference (delta) between the actual input signal and a quantized
approximation of the preceding input signal sample.
• This is represented in Figure 14 with a sample-and-hold, comparator, up-down
counter staircase generator, and a D-type flip-flop (D-FF) to derive the digital pulse
stream.
• The continuous analog signal is band-limited in the low-pass filter (LPF) to prevent
aliasing distortion, as in any sampling system.
• The analog signal VA is then compared to its discrete approximation VB
Delta Modulation
54. 54
1. Introduction
Noise is a general term which is used to describe an unwanted signal
which affects a wanted signal. These unwanted signals arise from a
variety of sources which may be considered in one of two main
categories:-
•Interference, usually from a human source (man made)
•Naturally occurring random noise
Interference
Interference arises for example, from other communication systems
(cross talk), 50 Hz supplies (hum) and harmonics, switched mode
power supplies, thyristor circuits, ignition (car spark plugs) motors
… etc.
55. 55
1. Introduction (Cont’d)
Natural Noise
Naturally occurring external noise sources include atmosphere disturbance
(e.g. electric storms, lighting, ionospheric effect etc), so called ‘Sky Noise’
or Cosmic noise which includes noise from galaxy, solar noise and ‘hot
spot’ due to oxygen and water vapour resonance in the earth’s atmosphere.
56. 56
2. Thermal Noise (Johnson Noise)
This type of noise is generated by all resistances (e.g. a resistor,
semiconductor, the resistance of a resonant circuit, i.e. the real part of the
impedance, cable etc).
Experimental results (by Johnson) and theoretical studies (by Nyquist) give
the mean square noise voltage as
)(4 2
2_
voltTBRkV
Where k = Boltzmann’s constant = 1.38 x 10-23 Joules per K
T = absolute temperature
B = bandwidth noise measured in (Hz)
R = resistance (ohms)
57. 57
2. Thermal Noise (Johnson Noise) (Cont’d)
The law relating noise power, N, to the temperature and bandwidth is
N = k TB watts
Thermal noise is often referred to as ‘white noise’ because it has a
uniform ‘spectral density’.
58. 58
3. Shot Noise
• Shot noise was originally used to describe noise due to random
fluctuations in electron emission from cathodes in vacuum tubes
(called shot noise by analogy with lead shot).
• Shot noise also occurs in semiconductors due to the liberation of
charge carriers.
• For pn junctions the mean square shot noise current is
Where
is the direct current as the pn junction (amps)
is the reverse saturation current (amps)
is the electron charge = 1.6 x 10-19 coulombs
B is the effective noise bandwidth (Hz)
• Shot noise is found to have a uniform spectral density as for thermal
noise
22
)(22 ampsBqIII eoDCn
59. 59
Noise may be quantified in terms of
noise power spectral density, po watts per
Hz, from which Noise power N may be
expressed as
N= po Bn watts
8. Noise Evaluation (Cont’d)
Ideal low pass filter
Bandwidth B Hz = Bn
N= po Bn watts
Practical LPF
3 dB bandwidth shown, but noise does not suddenly cease
at B3dB
Therefore, Bn > B3dB, Bn depends on actual filter.
N= p0 Bn
In general the equivalent noise bandwidth is > B3dB.
62. • RF Stage- filters the desired station and amplifies weak antenna
signal
• DETECTOR- removes information from the carrier
• AF Amp- power amplifier to drive the speaker
TRF
RF
STAGE
RF
STAGE
DETECTOR AF
AMP
63. • Design of AM/FM radio receiver
• The radio receiver has to be cost effective
• Requirements:
– Has to work with both AM and FM signals
– Tune to and amplify desired radio station
– Filter out all other stations
– Demodulator has to work with all radio stations regardless of carrier frequency
• For the demodulator to work with any radio signal, we “convert” the carrier
frequency of any radio signal to
Intermediate Frequency (IF)
• Radio receiver design can be optimized for that frequency
• IF filter and a demodulator for IF frequency
AM/FM Radio Receiver
64. RFTuner IF Filter Demodulator Audio
Amplifier
•This is known as the “Superheterodyne” receiver
•Two stages: RF and IF (filtering and amplification)
•The receiver was designed by Armstrong
RF Section
•Tunes to the desired RF frequency,
•Includes RF bandpass filter centered around
•The bandwidth
•Usually not narrowband, passes the desired radio station and
adjacent stations
65. • The minimum bandwidth of RF filter:
• Passes the desired radio channel, and adjacent channels
• RF-IF converter:
– Converts carrier frequencyIF frequency
• How can we convert signals with different RF frequencies to the same IF
frequency?
• Local oscillator with a center frequency
is a function of RF carrier frequency
TRF BB
IFcLO fff
RFTuner IF Filter Demodulator Audio
Amplifier
67. This technique combines time-domain samples from different message signals
(sampled at the same rate) and transmits them together across the same channel.
The multiplexing is performed using a commutator (switch) as shown in Figure
3.19. At the receiver a decommutator (switch) is used in synchronism with the
commutator to demultiplex the data.
TDM system is very sensitive to symbol dispersion, that is, to variation of
amplitude with frequency or lack of proportionality of phase with frequency.
This problem may be solved through equalization of both magnitude and phase.
One of the methods used to synchronize the operations of multiplexing and
demultiplexing is to organize the mutiplexed stream of data as frames with a
special pattern. The pattern is known to the receiver and can be detected very
easily.
Time Division Multiplexing
71. • These three properties are shared by light and radio waves
• For both reflection and refraction, it is assumed that the
surfaces involved are much larger than the wavelength; if not,
diffraction will occur
Reflection, Refraction, and Diffraction
72. • Ground-Wave propagation
• Ionosphere propagation
• Line of sight.
• Space Wave propogation
• Sky Wave
Terrestrial Propagation
73. • Frequencies up to 2 MHz.
• Vertically polarized in order to minimize currents induced in
the ground creating losses.
• Further from transmitter the more horizontal the wave front
becomes.
• Ground waves attenuate quickly above 2 MHz.
• Users: Military (15 KHz and 60 KHz)
Loran (100 KHz)
AM broadcast.
Ground Waves
74. • Three main regions: D, E, and F layers(F1 and F2)
• Ionization increases with altitude and is greater during the
day.
• D and E layers diminish at night.
• Follows 11 year sunspot cycle.
• Signal returns by a form of refraction.
• D and E layers absorb low frequencies( 8-10Mhz) during the
day therefore low frequencies propagate better at night.
Ionosphere Propagation
75.
76. • Signals in the VHF and higher range are not usually returned
to earth by the ionosphere
• Most terrestrial communication at these frequencies uses
direct radiation from the transmitter to the receiver
• This type of propagation is referred to as space-wave, line-of-
sight, or troposphere propagation
Line-of-Sight Propagation
77. • Space Waves: travel directly from an antenna to another without
reflection on the ground. Occurs when both antennas are within line of
sight of each another, distance is longer that line of sight because most
space waves bend near the ground and follow practically a curved path.
Antennas must display a very low angle of emission in order that all the
power is radiated in direction of the horizon instead of escaping in the sky.
A high gain and horizontally polarized antenna is thus highly
recommended.
• Sky Wave (Skip/ Hop/ Ionosphere Wave) is the propagation of radio waves
bent (refracted) back to the Earth's surface by the ionosphere. HF radio
communication (3 and 30 MHz) is a result of sky wave propagation.
Space Wave, Sky Wave