This document summarizes GSM architecture and call flows, including inter-MSC and intra-MSC call flows. Inter-MSC call flow occurs between two different MSCs, while intra-MSC call flow is between two BSCs within the same MSC. The inter-MSC call flow involves signaling between the BSC, MSC-O, MSC-T, HLR, and RNC to set up and release the call bearers. The intra-MSC call flow involves signaling between the MS-O, BSC-O, MSC/VLR, MGW, HLR, BSC-T, and MS-T to authenticate, set up, and release call bearers within a single MSC
This document discusses various digital modulation techniques used in digital communications. It describes amplitude shift keying (ASK), frequency shift keying (FSK), phase shift keying (PSK) including binary PSK (BPSK) and quadrature PSK (QPSK). It provides block diagrams and explanations of modulators and demodulators for ASK, FSK, BPSK and QPSK. It also discusses M-ary encoding techniques that can transmit more than two bits simultaneously to reduce bandwidth.
M-ary encoding allows for digital signals with multiple possible conditions or voltage levels through the use of multiple binary variables. The number of conditions possible is represented by M, while the number of bits needed to produce those conditions is given by the logarithmic relationship N = log2M. M-ary PSK and M-ary QAM are two common types of M-ary encoding. M-ary PSK varies the phase of a carrier signal, while M-ary QAM varies both the amplitude and phase, allowing for greater power efficiency but identical bandwidth efficiency as M-ary PSK. Both modulation schemes use a constellation diagram to represent the multiple symbol states.
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
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.
Frequency shift keying (FSK) is a digital modulation technique that encodes digital information by shifting the frequency of a carrier wave. There are different types of FSK including binary FSK, which uses two discrete frequencies to represent binary 1 and 0, and double frequency shift keying (DFSK), which uses four frequencies to transmit two independent data streams simultaneously. FSK modulation can be demodulated using either FM detector demodulators, which treat the FSK signal as an FM signal, or filter-type demodulators, which use optimal filters matched to the FSK signal parameters. The filters are used to detect the mark and space frequencies, and a decision circuit then determines which was transmitted.
This document discusses different types of traveling wave antennas, including long wire antennas and V antennas. It provides definitions of traveling wave antennas as non-resonant antennas where standing waves do not exist along the length. Long wire antennas are classified as having a length between 1-many wavelengths. Their current distribution attenuates along the length due to losses. V antennas consist of two wire antennas arranged horizontally to form a V shape. They can be resonant or non-resonant. Rhombic antennas are formed from two connected V antennas in a diamond shape and are highly directional but require large spaces. The document provides examples of their usage and concludes with designing a rhombic antenna.
This document summarizes GSM architecture and call flows, including inter-MSC and intra-MSC call flows. Inter-MSC call flow occurs between two different MSCs, while intra-MSC call flow is between two BSCs within the same MSC. The inter-MSC call flow involves signaling between the BSC, MSC-O, MSC-T, HLR, and RNC to set up and release the call bearers. The intra-MSC call flow involves signaling between the MS-O, BSC-O, MSC/VLR, MGW, HLR, BSC-T, and MS-T to authenticate, set up, and release call bearers within a single MSC
This document discusses various digital modulation techniques used in digital communications. It describes amplitude shift keying (ASK), frequency shift keying (FSK), phase shift keying (PSK) including binary PSK (BPSK) and quadrature PSK (QPSK). It provides block diagrams and explanations of modulators and demodulators for ASK, FSK, BPSK and QPSK. It also discusses M-ary encoding techniques that can transmit more than two bits simultaneously to reduce bandwidth.
M-ary encoding allows for digital signals with multiple possible conditions or voltage levels through the use of multiple binary variables. The number of conditions possible is represented by M, while the number of bits needed to produce those conditions is given by the logarithmic relationship N = log2M. M-ary PSK and M-ary QAM are two common types of M-ary encoding. M-ary PSK varies the phase of a carrier signal, while M-ary QAM varies both the amplitude and phase, allowing for greater power efficiency but identical bandwidth efficiency as M-ary PSK. Both modulation schemes use a constellation diagram to represent the multiple symbol states.
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
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.
Frequency shift keying (FSK) is a digital modulation technique that encodes digital information by shifting the frequency of a carrier wave. There are different types of FSK including binary FSK, which uses two discrete frequencies to represent binary 1 and 0, and double frequency shift keying (DFSK), which uses four frequencies to transmit two independent data streams simultaneously. FSK modulation can be demodulated using either FM detector demodulators, which treat the FSK signal as an FM signal, or filter-type demodulators, which use optimal filters matched to the FSK signal parameters. The filters are used to detect the mark and space frequencies, and a decision circuit then determines which was transmitted.
This document discusses different types of traveling wave antennas, including long wire antennas and V antennas. It provides definitions of traveling wave antennas as non-resonant antennas where standing waves do not exist along the length. Long wire antennas are classified as having a length between 1-many wavelengths. Their current distribution attenuates along the length due to losses. V antennas consist of two wire antennas arranged horizontally to form a V shape. They can be resonant or non-resonant. Rhombic antennas are formed from two connected V antennas in a diamond shape and are highly directional but require large spaces. The document provides examples of their usage and concludes with designing a rhombic antenna.
The document discusses various digital communication techniques including linear vs nonlinear PCM encoding, idle channel noise reduction methods, coding methods like level-at-a-time, digit-at-a-time and word-at-a-time. It also discusses analog companding using A-law and μ-law, digital companding, vocoders, delta modulation, DPCM, intersymbol interference causes and eye patterns.
The document discusses various telecommunication technologies used by BSNL including OCB-283, CDMA, GSM, ISDN, broadband, and transmission lines. It provides details on each technology such as what they are, how they work, their applications and advantages. The document concludes that the internship helped gain practical knowledge about the switching exchanges and telecommunication networks that were previously only studied theoretically.
Modulation involves adding information to a carrier signal. Digital modulation provides more information capacity, compatibility with digital services, higher security, better quality, and faster availability compared to analog modulation. Common digital modulation techniques include amplitude-shift keying (ASK), frequency-shift keying (FSK), phase-shift keying (PSK) and their variants. PSK techniques include binary PSK (BPSK), quadrature PSK (QPSK) and differential PSK (DPSK). QPSK transmits twice as much data as BPSK within the same bandwidth. DPSK avoids the need for a coherent reference signal at the receiver. Key considerations in modulation include power efficiency, bandwidth efficiency and bit error rate.
Application WDM(wavelength division multiplexing) For COMPSEPatel Ankit
This document discusses the application of wavelength division multiplexing (WDM) in three contexts:
1) Fibre optics, where WDM is used to transmit multiple high-speed digital data streams over a single optical fibre by assigning each stream a dedicated wavelength of light.
2) Aircraft applications, where WDM can enable future aircraft networks that have high capacity, flexibility, security and low cost.
3) RF avionics, where WDM transmission of RF signals over optical fibre has advantages over coaxial cable by offering higher bandwidth and immunity to electromagnetic interference.
The document discusses various digital modulation schemes, their advantages, disadvantages, and applications. It covers schemes such as DSB-SC, SSB-SC, VSB-SC, FM, PM, PSK, ASK, PAM, QAM, and their uses in applications like analog and digital television broadcasting, radio broadcasting, satellite transmission, cable communication, and optical and telephone communications. Key aspects covered are power and bandwidth efficiency, complexity of generation and detection, immunity to noise, and ability to transmit multiple bits per symbol.
Examples of wireless communication systems, paging systems, cordless telephone systems, cellular telephone systems,evolution of mobile phone, MSC, MTSO, PSTN, Mobile communication, wireless link, subscriber,
A Base Transceiver Station (BTS) facilitates wireless communication between user equipment and networks. It encodes, encrypts, and modulates RF signals that are transmitted from antennas. A BTS consists of transceivers, antennas, rectifiers, Radio Remote Units (RRU), Common Public Radio Interface (CPRI), GSM Transmission & Management Units (GTMU), Universal Main Processing & Transmission Units (UMPT), and Site Monitoring Units (SMU). The BTS communicates with mobile stations and Base Station Controllers.
This document discusses AM radio transmission and reception. It describes how AM radio works by taking an input signal like audio and modulating a carrier wave to transmit it through the air. It explains that modulation involves modifying a high frequency carrier signal with a low frequency audio signal. It also discusses how early radio receivers worked by tuning different radio frequency channels, but that modern radios use the superheterodyne principle to convert signals to a fixed intermediate frequency for better selectivity.
Wireless cellular networks divide geographic areas into cells served by base stations to allow for frequency reuse. As users travel between cells, their calls are handed off seamlessly. Cellular systems improve capacity by allocating unique frequency groups to each cell and reusing the same frequencies in cells sufficiently distant from each other. Larger networks connect multiple base stations and mobile switching centers to facilitate roaming and complete calls between mobile and fixed users.
Single Sideband Suppressed Carrier (SSB-SC)Ridwanul Hoque
Single-sideband suppressed carrier (SSB-SC) modulation improves spectral efficiency by transmitting only one sideband. It requires a bandwidth equal to the signal bandwidth. SSB-SC can be detected coherently using multiplication by the carrier. Quadrature amplitude modulation (QAM) transmits two baseband signals over the same bandwidth using in-phase and quadrature carriers that are 90 degrees out of phase. Vestigial sideband (VSB) modulation is a compromise between DSB and SSB that inherits advantages of both while requiring only slightly greater bandwidth than SSB. It is used for broadcast television transmission.
1) The document presents information about a magic tee, which is a waveguide component used in microwave engineering systems.
2) A magic tee has four ports and is able to split or combine signals passing through in specific ways depending on which port is used.
3) The document discusses the working, operation, and S-matrix of a magic tee. It also provides examples of how magic tees can be used for applications like impedance measurement, duplexing, and mixing.
This document describes the process of frequency modulation and demodulation through MATLAB simulation. It involves 5 tasks:
1) Modulation using a single tone modulating signal and analysis of the modulated signal spectrum.
2) Repeating task 1 using a multi-tone modulating signal.
3) Demodulation of the modulated signal using synchronous detection.
4) Repeating tasks 1-3 using a different multi-tone modulating signal.
5) Repeating tasks 1-3 using real speech signals as the modulating signal.
The MATLAB code generates the modulated signal, plots the modulating signal, carrier signal and modulated signal spectra. It also calculates the modulation index and modulated signal power for different modulation conditions
applications of planar transmission linesPARNIKA GUPTA
This document discusses various types of planar transmission lines and their applications. It describes microstrip lines, striplines, slotlines, finlines, and coplanar waveguides. For each type, it provides details on their structure, properties like impedance and Q factor, and common applications. Key applications discussed include microwave integrated circuits, filters, antennas, and wireless communication systems. The document concludes by noting ongoing work to improve transmission line properties and transmission speeds for communication applications.
This document discusses various digital modulation techniques. It begins by defining modulation as adding information to a carrier signal. It then distinguishes between analog and digital modulation. Digital modulation modulates an analog carrier signal with a discrete signal, and can be considered as converting digital-to-analog and vice versa. Some key digital modulation techniques discussed include amplitude shift keying (ASK), frequency shift keying (FSK), phase shift keying (PSK), quadrature amplitude modulation (QAM), and differential phase shift keying (DPSK). Metrics for comparing digital modulation techniques include power efficiency, bandwidth efficiency, and implementation cost-effectiveness.
CDMA2000 and WCDMA are the two main 3G standards. CDMA2000 uses a 1.25 MHz bandwidth and has achieved success in markets like Korea and Japan, with over 80 million subscribers. It provides broader coverage than WCDMA which uses 5 MHz bandwidth and operates at higher frequencies. While WCDMA's initial data rate was 384 Kbps, CDMA2000's 1xEV-DO can support up to 2.4 Mbps, giving it a performance advantage currently. Both standards continue to evolve but CDMA2000 has proven successful in commercial deployments in Asia.
Double Side band Suppressed carrier (DSB-SC) Modulation and Demodulation.SAiFul IslAm
This document describes an experiment on double sideband suppressed carrier (DSB-SC) modulation and demodulation performed by electrical engineering students at the University of Asia Pacific. The objectives were to observe DSB-SC modulation using an MC1496 modulator and examine synchronous demodulation of DSB-SC signals. The experiment involved generating a message signal, carrier signal, and DSB-SC modulated signal. A balanced modulator was used to produce the DSB-SC signal. Synchronous demodulation using a balanced multiplier, low-pass filter, and same carrier signal as the modulator recovered the original message signal from the DSB-SC signal. The students observed input and output waveforms and discussed the circuit connections and results
Modulation is the process of varying one or more properties of a high frequency carrier signal with respect to a modulating signal. This allows signals that are not suitable for direct transmission, such as audio signals, to be combined with a carrier wave for transmission. The three key parameters of a carrier wave that can be modulated are amplitude, frequency, and phase. The main types of modulation are amplitude modulation (AM), frequency modulation (FM), and phase modulation (PM). Demodulation is the process of extracting the original signal from the modulated carrier wave at the receiver. Modulation is necessary because antennas can only efficiently radiate wavelengths comparable to their size, so audio frequencies would require impractically large antennas for transmission, whereas higher carrier
Pulse Amplitude (PAM)
Pulse Width (PWM/PLM/PDM)
Pulse Position (PPM)
Comparison of PAM, PWM and PPM
Pulse Code (PCM)
Delta (DM)
Comparison of DM and PCM
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 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.
The document discusses various digital communication techniques including linear vs nonlinear PCM encoding, idle channel noise reduction methods, coding methods like level-at-a-time, digit-at-a-time and word-at-a-time. It also discusses analog companding using A-law and μ-law, digital companding, vocoders, delta modulation, DPCM, intersymbol interference causes and eye patterns.
The document discusses various telecommunication technologies used by BSNL including OCB-283, CDMA, GSM, ISDN, broadband, and transmission lines. It provides details on each technology such as what they are, how they work, their applications and advantages. The document concludes that the internship helped gain practical knowledge about the switching exchanges and telecommunication networks that were previously only studied theoretically.
Modulation involves adding information to a carrier signal. Digital modulation provides more information capacity, compatibility with digital services, higher security, better quality, and faster availability compared to analog modulation. Common digital modulation techniques include amplitude-shift keying (ASK), frequency-shift keying (FSK), phase-shift keying (PSK) and their variants. PSK techniques include binary PSK (BPSK), quadrature PSK (QPSK) and differential PSK (DPSK). QPSK transmits twice as much data as BPSK within the same bandwidth. DPSK avoids the need for a coherent reference signal at the receiver. Key considerations in modulation include power efficiency, bandwidth efficiency and bit error rate.
Application WDM(wavelength division multiplexing) For COMPSEPatel Ankit
This document discusses the application of wavelength division multiplexing (WDM) in three contexts:
1) Fibre optics, where WDM is used to transmit multiple high-speed digital data streams over a single optical fibre by assigning each stream a dedicated wavelength of light.
2) Aircraft applications, where WDM can enable future aircraft networks that have high capacity, flexibility, security and low cost.
3) RF avionics, where WDM transmission of RF signals over optical fibre has advantages over coaxial cable by offering higher bandwidth and immunity to electromagnetic interference.
The document discusses various digital modulation schemes, their advantages, disadvantages, and applications. It covers schemes such as DSB-SC, SSB-SC, VSB-SC, FM, PM, PSK, ASK, PAM, QAM, and their uses in applications like analog and digital television broadcasting, radio broadcasting, satellite transmission, cable communication, and optical and telephone communications. Key aspects covered are power and bandwidth efficiency, complexity of generation and detection, immunity to noise, and ability to transmit multiple bits per symbol.
Examples of wireless communication systems, paging systems, cordless telephone systems, cellular telephone systems,evolution of mobile phone, MSC, MTSO, PSTN, Mobile communication, wireless link, subscriber,
A Base Transceiver Station (BTS) facilitates wireless communication between user equipment and networks. It encodes, encrypts, and modulates RF signals that are transmitted from antennas. A BTS consists of transceivers, antennas, rectifiers, Radio Remote Units (RRU), Common Public Radio Interface (CPRI), GSM Transmission & Management Units (GTMU), Universal Main Processing & Transmission Units (UMPT), and Site Monitoring Units (SMU). The BTS communicates with mobile stations and Base Station Controllers.
This document discusses AM radio transmission and reception. It describes how AM radio works by taking an input signal like audio and modulating a carrier wave to transmit it through the air. It explains that modulation involves modifying a high frequency carrier signal with a low frequency audio signal. It also discusses how early radio receivers worked by tuning different radio frequency channels, but that modern radios use the superheterodyne principle to convert signals to a fixed intermediate frequency for better selectivity.
Wireless cellular networks divide geographic areas into cells served by base stations to allow for frequency reuse. As users travel between cells, their calls are handed off seamlessly. Cellular systems improve capacity by allocating unique frequency groups to each cell and reusing the same frequencies in cells sufficiently distant from each other. Larger networks connect multiple base stations and mobile switching centers to facilitate roaming and complete calls between mobile and fixed users.
Single Sideband Suppressed Carrier (SSB-SC)Ridwanul Hoque
Single-sideband suppressed carrier (SSB-SC) modulation improves spectral efficiency by transmitting only one sideband. It requires a bandwidth equal to the signal bandwidth. SSB-SC can be detected coherently using multiplication by the carrier. Quadrature amplitude modulation (QAM) transmits two baseband signals over the same bandwidth using in-phase and quadrature carriers that are 90 degrees out of phase. Vestigial sideband (VSB) modulation is a compromise between DSB and SSB that inherits advantages of both while requiring only slightly greater bandwidth than SSB. It is used for broadcast television transmission.
1) The document presents information about a magic tee, which is a waveguide component used in microwave engineering systems.
2) A magic tee has four ports and is able to split or combine signals passing through in specific ways depending on which port is used.
3) The document discusses the working, operation, and S-matrix of a magic tee. It also provides examples of how magic tees can be used for applications like impedance measurement, duplexing, and mixing.
This document describes the process of frequency modulation and demodulation through MATLAB simulation. It involves 5 tasks:
1) Modulation using a single tone modulating signal and analysis of the modulated signal spectrum.
2) Repeating task 1 using a multi-tone modulating signal.
3) Demodulation of the modulated signal using synchronous detection.
4) Repeating tasks 1-3 using a different multi-tone modulating signal.
5) Repeating tasks 1-3 using real speech signals as the modulating signal.
The MATLAB code generates the modulated signal, plots the modulating signal, carrier signal and modulated signal spectra. It also calculates the modulation index and modulated signal power for different modulation conditions
applications of planar transmission linesPARNIKA GUPTA
This document discusses various types of planar transmission lines and their applications. It describes microstrip lines, striplines, slotlines, finlines, and coplanar waveguides. For each type, it provides details on their structure, properties like impedance and Q factor, and common applications. Key applications discussed include microwave integrated circuits, filters, antennas, and wireless communication systems. The document concludes by noting ongoing work to improve transmission line properties and transmission speeds for communication applications.
This document discusses various digital modulation techniques. It begins by defining modulation as adding information to a carrier signal. It then distinguishes between analog and digital modulation. Digital modulation modulates an analog carrier signal with a discrete signal, and can be considered as converting digital-to-analog and vice versa. Some key digital modulation techniques discussed include amplitude shift keying (ASK), frequency shift keying (FSK), phase shift keying (PSK), quadrature amplitude modulation (QAM), and differential phase shift keying (DPSK). Metrics for comparing digital modulation techniques include power efficiency, bandwidth efficiency, and implementation cost-effectiveness.
CDMA2000 and WCDMA are the two main 3G standards. CDMA2000 uses a 1.25 MHz bandwidth and has achieved success in markets like Korea and Japan, with over 80 million subscribers. It provides broader coverage than WCDMA which uses 5 MHz bandwidth and operates at higher frequencies. While WCDMA's initial data rate was 384 Kbps, CDMA2000's 1xEV-DO can support up to 2.4 Mbps, giving it a performance advantage currently. Both standards continue to evolve but CDMA2000 has proven successful in commercial deployments in Asia.
Double Side band Suppressed carrier (DSB-SC) Modulation and Demodulation.SAiFul IslAm
This document describes an experiment on double sideband suppressed carrier (DSB-SC) modulation and demodulation performed by electrical engineering students at the University of Asia Pacific. The objectives were to observe DSB-SC modulation using an MC1496 modulator and examine synchronous demodulation of DSB-SC signals. The experiment involved generating a message signal, carrier signal, and DSB-SC modulated signal. A balanced modulator was used to produce the DSB-SC signal. Synchronous demodulation using a balanced multiplier, low-pass filter, and same carrier signal as the modulator recovered the original message signal from the DSB-SC signal. The students observed input and output waveforms and discussed the circuit connections and results
Modulation is the process of varying one or more properties of a high frequency carrier signal with respect to a modulating signal. This allows signals that are not suitable for direct transmission, such as audio signals, to be combined with a carrier wave for transmission. The three key parameters of a carrier wave that can be modulated are amplitude, frequency, and phase. The main types of modulation are amplitude modulation (AM), frequency modulation (FM), and phase modulation (PM). Demodulation is the process of extracting the original signal from the modulated carrier wave at the receiver. Modulation is necessary because antennas can only efficiently radiate wavelengths comparable to their size, so audio frequencies would require impractically large antennas for transmission, whereas higher carrier
Pulse Amplitude (PAM)
Pulse Width (PWM/PLM/PDM)
Pulse Position (PPM)
Comparison of PAM, PWM and PPM
Pulse Code (PCM)
Delta (DM)
Comparison of DM and PCM
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 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.
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Design and implementation of qpsk modulator using digital subcarrierGongadi Nagaraju
This document is a technical report on the design and implementation of a QPSK modulator using a digital subcarrier. It was submitted by Gongadi Nagaraju in partial fulfillment of an M.Tech degree in electronics and communication engineering. The report includes an abstract, introduction to modulation techniques for satellite communication, analysis of QPSK modulation, block diagram of the proposed digitally implemented QPSK modulator, simulation results, plans for hardware realization, and references. The goal is to design a new approach that minimizes component count and circuit board size by implementing modulation functions digitally inside an FPGA rather than with analog components.
Application Of Flexible All Graphite Paper Based Field...Emily Jones
This document describes a flexible all graphite paper field effect transistor that can be used as a strain sensor. The transistor is fabricated using low-cost and sustainable materials like cellulose paper as the substrate and dielectric, and pencil graphite for the source, drain, channel and gate. It shows good sensitivity for detecting low tensile and compressive strains. When integrated with gloves, it can be used to detect human motion and has potential as a flexible strain sensor.
Data Communications (under graduate course) Lecture 4 of 5Randa Elanwar
Undergraduate course content:
Introduction: Types and sources of data, communication models, standards.
Data transmission: techniques, transmission media and characteristics.
Information theory: Information sources, information measure, entropy, source codes.
Line codes: characteristics, return-to-zero and non-return-to-zero signaling, bipolar alternate mark inversion, code (radix, redundancy and efficiency), important codes in current use, frequency spectra characteristics of common line codes, receiver clock synchronization, optical fiber systems, scramblers.
Modems: characteristics, modulation, equalization, control, V-standards.
Error Control: Transmission impairments, forward error control, linear block codes, feedback error control.
A Review of Relay selection based Cooperative Wireless Network for Capacity E...IRJET Journal
This document discusses relay selection in cooperative wireless networks to enhance network capacity. It reviews cooperative communication techniques like amplify-and-forward and decode-and-forward that achieve spatial diversity without requiring multiple antennas on a device. The selection of relay nodes has a significant impact on the total network capacity. It aims to study cooperative relay node assignment that allows multiple source-destination pairs to compete for the same pool of relay nodes, with each pair able to be assigned multiple relays.
Analog-to-digital conversion (ADC) is an electronic process in which a continuously variable, or analog, the signal is changed into a multilevel digital signal without altering its essential content.
This document provides an overview of principles of communication. It discusses key components of a communication system including the transmitter, communication channel, and receiver. It describes different forms of modulation used in analog and digital communication systems, including amplitude modulation, frequency modulation, and pulse modulation. It also discusses antennas, communication channels, receivers, and applications of communication systems like data transmission, fax, radio, television, and satellite communication.
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.
A significant problem in Multicarrier Code Division Multiple Access (MC-
CDMA) system is the possibility of high Peak to Average Power Ratio (PAPR). This is due
to the cumulative sum of N subcarrier peaks in the transmitted signals which reduces Power
efficiency, resolution and battery life. In this paper a technique is proposed to make use of
Inverse Discrete Cosine Transform (IDCT) and Inverse Discrete Wavelet Transform
(IDWT) based Multicarrier Code Division Multiple Access (MC-CDMA) system. This
system is in combination with Modified Exponential Companding with Clipping Transform
(MECCT) technique which reduces PAPR and that is analyzed over Additive White
Gaussian Noise (AWGN) channel, Rayleigh and Stanford University Interim (SUI)
multipath fading channel.
This document is Sakib Hussain's vocational training report from his 2-week training at All India Radio Kolkata. It details his training experiences at 4 centers: Akash Bani Bhaban (control room), Golf Green FM transmitter center, HPT Amtola (medium wave transmission), and HPT Amtola (medium and short wave transmission). The report is divided into 4 parts covering introductions to communication systems, AIR studio and broadcasting, AIR MW and SW transmission systems, and AIR FM transmission systems.
Performance analysis of image transmission with various channel conditions/mo...TELKOMNIKA JOURNAL
This paper investigates the impact of different modulation techniques for
digital communication systems that employ quadrature phase shift keying
(QPSK) and quadrature amplitude modulation (16-QAM and 64-QAM) to
transmit images over AWGN and Rayleigh fading channels for the cellular
mobile networks. In the further steps, wiener and median filters has been
adopted to the simulation are used at the receiver side to remove the impulsive
noise present in the received image. This work is performed to evaluate
the transmission of two dimensional (2D) gray-scale and color-scale (RGB)
images with different values from signal to noise ratios (SNR), such as;
(5, 10 and 15) dB over different channels. The correct conclusions are made
by comparing many of the observed Matlab simulation results. This was
carried out through the results that measure the quality of received image,
which is analyzes in terms of SNRimage peak signal to noise ratio (PSNR) and
mean square error (MSE).
Modulation is the process of varying the characteristics of a high-frequency carrier wave in order to transmit a message signal or information signal. There are two main types of modulation: analog and digital. Analog modulation varies amplitude, frequency, or phase of the carrier wave based on the message signal. Common analog modulation techniques are amplitude modulation (AM), frequency modulation (FM), and phase modulation (PM). Digital modulation maps discrete messages to discrete variations in one or more properties of the carrier wave. Common digital modulation techniques are amplitude-shift keying (ASK), frequency-shift keying (FSK), phase-shift keying (PSK), and minimum-shift keying (MSK). Modulation is necessary for communication systems in order
This document provides an overview of principles of communication. It discusses key components of a communication system including the transmitter, communication channel, and receiver. It describes different forms of modulation used in analog and digital communication systems, including amplitude modulation, frequency modulation, and pulse modulation. It also discusses antennas, transmission media, data transmission methods like email and fax, and aspects of space communication.
A communication channel is a medium through which information is transmitted between two points. It can be either guided or unguided. Guided channels use physical transmission media like twisted pair cables, coaxial cables, and fiber optic cables to transmit signals. Unguided channels transmit signals through the air without physical connections, using technologies like microwaves, communication satellites, radio broadcasts, and cellular networks. Communication channels are evaluated based on their bandwidth, or how much data they can carry per unit of time. Fiber optic cables provide the highest bandwidth and fastest transmission speeds of all communication channel types.
Lecture Notes: EEEC6440315 Communication Systems - Spectral EfficiencyAIMST University
This document discusses methods for improving spectral efficiency in communication systems. It provides information on different modulation techniques and factors that influence spectral efficiency, such as signal-to-noise ratio, bandwidth efficiency, forward error correction, data compression, and MIMO. It also describes how modulation and demodulation are implemented using software-defined radios and digital signal processing. The pursuit of greater spectral efficiency is important given the finite amount of radio spectrum and growing demand for wireless services.
Bit error rate analysis of miso system in rayleigh fading channeleSAT Publishing House
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Communication Theory-1 project report || Carrier Acquisition in DSB_SC using coastas loop || Matlab code
1. PROJECTBASED LAB REPORT
On
Carrier Acquisition in DSB-SC using Costas Loop
Submitted in partial fulfilment of the
Requirements for the award of degree
Bachelor of Technology
In
Electronics and Communication Engineering
By
B. Ramesh Reddy - 160040074
A. Sanath Kumar - 160040053
B. Purna - 160040124
Under the guidance of
Mr. P. Raghavendra Rao
(Assistant Professor)
DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING
KONERU LAKSHMAIAH EDUCATIONAL FOUNDATION
Green Fields, Vaddeswaram, Guntur District
2. CERTIFICATE
This is to certify that the mini project entitled “CarrierAcquisition in DSB-SC
using Costas Loop”, is being submitted by “ A. Sanath Kumar-160040053,
B. Ramesh Reddy-160040074, B. Purna-160040124”in partial fulfillment for
the award of degree of Bachelor of Technology (B. Tech) in Electronics and
Communications Engineering is a record of confide work carried out by them
under our guidance during the academic year 2017-2018and it has been found
worthy of acceptance according to the requirements of the university.
Signature of The Project Guide Signature of Headof Department
Department of ECE
K L E F
3. KONERU LAKSHMAIAH EDUCATIONAL FOUNDATION
DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING
We hereby declare that this project based lab report entitled” Carrier
Acquisition in DSB-SC using Costas Loop” has been prepared by us in
partial fulfillment of the requirement for the award of degree “BACHELOR OF
TECHNOLOGY IN ELECTRONICS AND COMMUNICATIONS OF ENGINEERING”
during the academic year 2017-2018.
We also declare that this project based lab report is of our own effort
and it has not been submitted to any other university for the award of any
degree.
DECLARATION
4. Acknowledgement
We are greatly indebted to our KL University that has provided a healthy
environment to drive us to achieve our ambitions and goals. We would like to
express our sincerethanks to our projectinchargeMr. madam for the guidance,
and assistance they have provided in completing this project.
We express our gratitude to Dr. M Venu Gopala Rao sir for providing us with
adequate facilities, ways and means by which we are able to complete this
project.
My sincerethanksto Mr. P. RaghavendraRao sir in the Lab fortheir outstanding
support
throughout the project for the successful completion of the work.
With immense pleasure, we would like to thank the Head of the Department,
Dr. V. S. V. Prabhakar sirfor hisvaluablesuggestionsand guidancefor thetimely
completion of this project.
We are very much glad for having the support given by our principal, K. Subba
Rao sir who inspired us with his words filled with dedication and discipline
towards work.
We believe that “Practical Leads A Man Towards Performance”.
Last but not the least, a special thanks goes to the Parents, staff and classmates
who are helpful either directly or indirectly in completion of the mini project
5. S. No CONTENTS
1 Introduction
2 About Modulation and Demodulation
3 DSB-SC Transmission
4 Project Task1
5 Costas loop for DSB-SC demodulation
6 Project Task2
7 Multi-tone modulation
8 Project Task3
9 Base Band Modulation and Demodulation
10 Project Task4
11 Project Task5
12 Advantages and Disadvantages
13 Conclusion
14 Future Scope
15 References
6. 1.Introduction
The fundamental purpose of an electronic communications system is to transfer
information transmission, reception and processing of information between two or more
locations using electronic circuits. The original source information can be in Analog form, such
as human voice or music, or in digital form, such as binary coded numbers or alphanumeric
codes. Analog signals are time varying voltages or currents that are continuously changing,
such as sine and cosine waves. An Analog signal contains an infinite number of values. Digital
signals are voltages or currents that change in discrete steps or levels. The most common form
of digital signal is binary, which has two levels. All forms of information however must be
converted to electromagnetic energy before being propagated through an electronic
communication system.
There are numerous forms of communication. We have wired communication, wherein
examples are telephone, broadband internet at home, local area networks at office, just to name
a few. We also have wireless communication such as mobile, Wi-Fi, Bluetooth, radio
broadcast, TV broadcast, and many others. It seems that our lives could not function properly
without communication.
About Modulation and Demodulation
To transmit a message signal to a long distance over a communication channel, we need
to modify the message signal into a suitable form for efficient transmission over the channel.
Modification of the message signal is achieved by means of a process is known as modulation.
The transmission channel is best suited for high frequency signal transmission. The
high frequency signals are called carriers. Modulation is a scheme which alters some
characteristics of the high frequency carrier in accordance with the low frequency message
signal called the modulating signal. Modulation is performed in a transmitter by a circuit is
called a modulator. A carrier that has been acted on by an information system is called
modulated signal. Demodulation is a reverse process of modulation and converts the modulated
carrier back to the original signal. Demodulation is performed in a receiver by a circuit called
demodulator.
Need for Modulation: There are various reasons why modulation is necessary in electronic
communication systems: (a) Ease of Radiation / Transmission (b) Multiplexing (c) Reduction
of Noise (d) Narrow banding (e) Channel Matching.
7. Types of Modulation:
Double-sideband suppressed-carrier transmission (DSB-SC) is transmission in
which frequencies produced by Amplitude modulation (AM) are symmetrically spaced above and
belowthe carrierfrequency andthe carrierlevel isreducedtothe lowestpractical level,ideallybeing
completely suppressed.
Inthe DSB-SCmodulation,unlikeinAM,the wave carrierisnottransmitted;thus,muchof the
power is distributed between the sidebands, which implies an increase of the cover in DSB-SC,
comparedto AM, for the same powerused.DSB-SCtransmissionisaspecial case of double-sideband
reduced carrier transmission. It is used for radio data systems.
In electronics and telecommunications, modulation is the process of varying one or more
properties of a periodic waveform, called the carrier signal, with a modulating signal that typically
contains information to In telecommunications, modulation is the process of conveying a message
signal, for example a digital bit stream or an Analog audio signal, inside another signal that can be
physicallytransmitted.Modulationof a sine waveformtransformsa basebandmessage signal intoa
pass band signal.
8. A modulator is a device that performs modulation. A demodulator (sometimes detector) is a device
that performsdemodulation,the inverseof modulation.The aim of Analogmodulationisto transfer
an Analog baseband (or lowpass) signal, for example an audio signal or TV signal, over an Analog
bandpasschannel atadifferentfrequency,forexampleoveralimitedradiofrequencybandoracable
TV network channel. The aim of digital modulationis to transfer a digital bit stream over an Analog
bandpasschannel,forexample overthe publicswitchedtelephone network(where abandpassfilter
limits the frequency range to 300–3400 Hz) or over a limited radio frequency band.
Task1: Consider a single tone modulating signal m(t ) cos1000t , and carrier signal c (t)
cos10
4
t .
1. Determine the expression for DSB-SC modulated signal in both time domain and
frequency domain.
2. Sketch the modulating signal m(t ) and its spectrum.
3. Sketch the carrier wave c (t ) and its spectrum.
4. Sketch the DSB-SC modulated signal DSB SC (t) and its spectrum.
5. Identify the USB and LSB spectra.
6. Determine the maximum and minimum amplitudes of the envelope.
MATLAB CODE FOR TASK-1:
clear all;
close all;
clc;
am=1; %Peak Amplitude of Modulating Signal
ac=1; %Peak Amplitude of Carrier Signal
fm=500; %Modulating Signal Frequency
fc=5000; %Carrier Frequency
fs=100000; %Sampling Frequency
ts=1/fs; %Sampling Interval
N=10000; %Number of Samples
t=(-N/2:1:(N/2-1))*ts; %Time Interval
m=am*cos(2*pi*fm*t); %Modulating Signal
c=ac*cos(2*pi*fc*t); %Carrier Signal
st=c.*m; %DSB-SC Signal
% TASK - 1
%Time Domain of all signals
subplot(3,2,1);
plot(t,m, 'red', 'LineWidth',1.5);axis([0 0.005 -2.5 2.5]);
xlabel('Time (seconds)');ylabel('Amplitude');title('Modulating Signal
signal');
grid on;
subplot(3,2,3);
plot(t,c, 'black', 'LineWidth',1.5);axis([0 0.005 -2.5 2.5]);
xlabel('Time (seconds)');ylabel('Amplitude');title('Carrier Signal
signal');
grid on;
subplot(3,2,5);
plot(t,st, 'blue', 'LineWidth',1.5);axis([0 0.005 -2.5 2.5]);
9. xlabel('Time (seconds)');ylabel('Amplitude(Volts)');title('Modulated
signal');
grid on;hold on
%Spectrums of all Signals
f=(-N/2:1:N/2-1)*fs/N;
M=abs((2/N)*fftshift(fft(m)));
C=abs((2/N)*fftshift(fft(c)));
SF=abs((2/N)*fftshift(fft(st)));
subplot(3,2,2);
plot(f,M/max(M), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude');title('Spectrum of Modulating
Signal signal');
grid on;
subplot(3,2,4);
plot(f,C/max(C), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude');title('Spectrum of Carrier
Signal signal');
grid on;
subplot(3,2,6);
plot(f,SF/max(SF), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude(Volts)');title('Spectrum of
Modulated signal');
grid on;
Su=(1/2)*ac*am*cos(2*pi*(fc+fm))*t;
Sl=(1/2)*ac*am*cos(2*pi*(fc-fm))*t;
%Maximum and Minimum amplitudes of the envelope
Amax = ac + am
Amin = ac - am
%Power Calculations
mu=am/ac %Modulation index
Pc=(ac^2)/2 %Carrier Power
Pu=Pc*(mu^2)/4 %USB POWER
Pl=Pc*(mu^2)/4 %LSB POWER
Ps=Pu+Pl %Total Side Band Power
Pt=Pc*(1+((mu^2)/2)) %Total Power of Modulated wave
10. Amax = 2
Amin = 0
mu = 1
Pc = 0.5000
Pu = 0.1250 Pl = 0.1250 Ps = 0.250 Pt = 0.75
Costas loop for DSB-SC demodulation
A Costas loop is a phase-locked loop (PLL) based circuit which is used
for carrierfrequency recovery from suppressed-carriermodulation signals (e.g. double-
sideband suppressedcarriersignals) andphase modulationsignals(e.g. BPSK, QPSK).Itwasinvented
by John P. Costas at General Electricin the 1950s. Its invention was described as having had "a
profound effect on modern digital communications". This loop,and its variations, is much-usedas a
methodof carrier acquisition(andsimultaneousmessage demodulation) incommunicationsystems,
both Analoganddigital.It has the propertyof beingable toderive a carrier fromthe receivedsignal,
even when there is no component at carrier frequency present in that signal (Eg, DSBSC). The
requirement is that the amplitude spectrum of the received signal be symmetrical about the
frequency.
Demodulation
11. Demodulation is extracting the original information-bearing signal from a modulated carrier
wave.These termsare traditionallyusedinconnectionwithradioreceivers,butmanyothersystems
use many kinds of demodulators. For example, in a modem, which is a contraction of the terms
modulator/demodulator,a demodulator is used to extract a serial digital data stream from a carrier
signal whichisusedto carry it througha telephone line,coaxial cable,oroptical fiber. Demodulation
was first used in radio receivers. In the wireless telegraphy radio systems used during the first 3
decades of radio (1884-1914) the transmitter did not communicate audio (sound) but transmitted
information in the form of pulses of radio waves that represented text messages in Morse code.
Therefore,the receivermerelyhadtodetectthe presence orabsence of the radiosignal,andproduce
a clicksound.The device thatdidthiswascalleda detector.The firstdetectorswere coherers,simple
devicesthatactedasaswitch.The termdetectorstuck,wasusedforothertypesof demodulatorsand
continues to be used to the present day for a demodulator in a radio receiver.
The firsttype of modulationusedtotransmitsoundoverradiowaveswasamplitudemodulation(AM),
invented by Reginald Fessendon around 1900. An AM radio signal can be demodulated by rectifying
it, removing the radio frequency pulses on one side of the carrier, converting it from alternating
current (AC) to a pulsating direct current (DC). The amplitude of the DC varies with the modulating
audiosignal,soitcandrive anearphone.Fessendoninventedthe firstAMdemodulatorin1904 called
the electrolyticdetector,consistingof a shortneedle dippingintoacup of dilute acid.The same year
JohnAmbrose Fleminginventedthe FlemingvalveorthermionicdiodewhichcouldalsorectifyanAM
signal.
Task 2: Use the CostasloopforDSB-SCdemodulationasshowninFig.1.ThisCostasloopacquire the
carrier signal using PLL and recover the message signal using synchronous detection technique as
showninFig1.Furtherinvestigate the impactof channel noise indemodulation/receptionof DSB-SC
wave. Now consider a single tone case.
12. 1. Add the noise variance such that the signal to noise ratio (SNR) of noisy DSB-SC modulated
signal is 20 dB.
2. Use noisy upper side frequency band for demodulation purpose. If necessary use band
pass filter.
3. Sketch the noisy DSB-SC modulated signal DSB - SC (t ) + n(t ) and its spectrum.
4. Sketch the demodulated output mˆ(t ) and its spectrum.
5. Find the output SNR and corresponding figure of merit.
6. Repeatthe above steps for SNR= 10 dB, 30dB and40dB and compare.Commentonresults.
MATLAB CODE FOR TASK-2:
clear all; close all; clc;
fc=5000; %%%% carrier frequency
fs=30000; %%%% Sample frequency
N=5000; %%%% Number of samples
Ts=1/fs; %%%% Sampling interval
t=(0:Ts:(N*Ts)- Ts); %%%% Time interval
f=(-N/2:1:N/2-1)*fs/N; %%%% Frequency interval
fm = 500; %%%% Modulating frequency
m = cos(2*pi*fm*t); %%%% Generation of message signal
M= abs((2/N)*fftshift(fft(m))); %%%% Spectrum of Message signal
c = cos(2*pi*fc*t); %%%% Generation of carrier signal
C=abs((2/N)*fftshift(fft(c))); %%%% Spectrum of Carrier signal
st=c.*m; %%%% Representation of the DSBSC
SF=abs((2/N)*fftshift(fft(st))); %%%% Spectrum of the DSBSC Signal
%NOISE ADDED
%DSB-SC signal with 10db noise
y3=awgn(st,10);
figure();
subplot(4,2,1);
plot(t,y3/max(y3), 'black', 'LineWidth',1.5);axis([0 0.005 -1.2 1.2]);
xlabel('Time (seconds)');ylabel('Amplitude');title('s(t) +10dB noise');
grid on;
%Spectrum of DSB-SC 10db noise added
Y3F=abs((2/N)*fftshift(fft(y3)));
subplot(4,2,2);
plot(f,Y3F/max(Y3F), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude(Volts)');title('Spectrum of 10db
Noise Modulated signal');
grid on;
%DSB-SC signal with 20db noise
y4=awgn(st,20);
subplot(4,2,3);
plot(t,y4/max(y4), 'black', 'LineWidth',1.5);axis([0 0.005 -1.2 1.2]);
xlabel('Time (seconds)');ylabel('Amplitude');title('s(t) +20dB noise');
grid on;
%Spectrum of DSB-SC 20db noise added
Y4F=abs((2/N)*fftshift(fft(y4)));
subplot(4,2,4);
plot(f,Y4F/max(Y4F), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude(Volts)');title('Spectrum of 20db
Noise Modulated signal');
grid on;
%DSB-SC signal with 30db noise
y5=awgn(st,30);
subplot(4,2,5);
plot(t,y5/max(y5), 'black', 'LineWidth',1.5);axis([0 0.005 -1.2 1.2]);
xlabel('Time (seconds)');ylabel('Amplitude');title('s(t) +30dB noise');
13. grid on;
%Spectrum of DSB-SC 30db noise added
Y5F=abs((2/N)*fftshift(fft(y5)));
subplot(4,2,6);
plot(f,Y5F/max(Y5F), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude(Volts)');title('Spectrum of 30db
Noise Modulated signal');
grid on;
%DSB-SC signal with 40db noise
y6=awgn(st,40);
subplot(4,2,7);
plot(t,y6/max(y6), 'black', 'LineWidth',1.5);axis([0 0.005 -1.2 1.2]);
xlabel('Time (seconds)');ylabel('Amplitude');title('s(t) +40dB noise');
grid on;
%Spectrum of DSB-SC 40db noise added
Y6F=abs((2/N)*fftshift(fft(y6)));
subplot(4,2,8);
plot(f,Y6F/max(Y6F), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude(Volts)');title('Spectrum of 40db
Noise Modulated signal');
grid on;
%%%%%%DEMODULATION USING COASTAS LOOP%%%%%%%
% DSB-SC signal
% -----------------------------------------------------------------------
% ---------------------------RECEIVER PART-------------------------------
N = length(y6);
t = 0:1:N-1; % Time vector
phi = zeros(1,N); % Phase vector of VCO initialize
s1 = zeros(1,N);
s2 = zeros(1,N);
y1 = zeros(1,N);
y2 = zeros(1,N);
for i = 1:N
if i>1
% The step in which phase is changed is pi*5*10*-5, it can be varied.
phi(i) = phi(i-1) - (5*10^-5)*pi*sign(y1(i-1)*y2(i-1));
end
s1(i) = st(i) * cos(2*pi*fc*t(i)/fs + phi(i));
s2(i) = st(i) * sin(2*pi*fc*t(i)/fs + phi(i));
% -----------------------INTEGRATOR------------------------------------
if i<=100
% If sample index is less than 100 (Tc/Ts) then we sum available previous
% samples
for j=1:i
y1(i) = y1(i) + s1(j);
y2(i) = y2(i) + s2(j);
end
else
% Summing previous 100 (Tc/Ts) values
for j = i-99:i
y1(i) = y1(i) + s1(j);
y2(i) = y2(i) + s2(j);
end
end
%----------------------------------------------------------------------
end
%Time domain of Demodulated signal
figure();
subplot(1,2,1);
plot(t,y1);title('Demodulated signal');axis([0 900 -10 10]);
xlabel('Time');ylabel('Amplitude');
14. %frequency domain of Demodulated signal
Y1F=abs((2/N)*fftshift(fft(y1)));
subplot(1,2,2);
plot(f,Y1F/max(Y1F), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude');title('Spectrum of Demodulated
signal');
grid on;
Multi-tone Modulation:
15. In multi-tone modulation modulating signal consists of more than one frequency
component where as in single-tone modulation modulating signal consists of only one
frequency component.
Task 3:Repeat the above Tasks1-2 for multi tone signal
m(t ) 2cos1000t sin1500t1.5cos 2000t
MATLAB CODE FOR TASK-3
clear all; close all; clc;
fc=5000; %carrier frequency
fs=30000; %Sample frequency
N=5000; %Number of samples
Ts=1/fs; %Sampling interval
t=(0:Ts:(N*Ts)- Ts); %TIME INTERVAL
f=(-N/2:1:N/2-1)*fs/N; %FREQUENCY INTERVAL
am1=2; %Peak Amplitude of Modulating Signal
am2=1.5; %Peak Amplitude of Modulating Signal
ac=1; %Peak Amplitude of Carrier Signal
m = am1.*cos(1000*pi*t)-sin(1500*pi*t)+am2.*cos(2000*pi*t);% Message signal
M=abs((2/N)*fftshift(fft(m))); %%% Spectrum of Message signal
c = ac.*cos(2*pi*fc*t); %%%% Generation of carrier signal
C=abs((2/N)*fftshift(fft(c))); %%%%Spectrum of Carrier signal
st=2.*m.*cos(2*pi*fc*t); %%%%Representation of the DSBSC Signal
SF=abs((2/N)*fftshift(fft(st))); %%%%Spectrum of the DSBSC Signal
figure();
%%%% Message signal
subplot(3,2,1);
plot(t,m/max(m), 'black', 'LineWidth',1.5);axis([0 0.005 -2.5 2.5]);
xlabel('Time (seconds)');ylabel('Amplitude');title('500 Hz message
signal');
grid on;
%%%% Spectrum of Message signal
subplot(3,2,2);
plot(f,abs(M/max(M)),'r','Linewidth',2); axis([-2*fc 2*fc -0.1 1.1]);
xlabel('f'); ylabel('Magnitude|'); title('Spectrum of Message Signal');
grid on
%%%% Carrier signal
subplot(3,2,3);
plot(t,c/max(c), 'b', 'LineWidth',1.5);axis([0 0.005 -2.5 2.5]);
xlabel('Time (seconds)');ylabel('Amplitude');title('Carrier Signal');
grid on;
%%%% Spectrum of Carrier Signal
subplot(3,2,4);
plot(f,abs(C/max(C)),'m','Linewidth',2); axis([-2*fc 2*fc -0.1 1.1]);
xlabel('f'); ylabel('Magnitude|'); title('Spectrum of carrier Signal');
grid on
%%%% DSBSC signal
subplot(3,2,5);
plot(t,st/max(st), 'b', 'LineWidth',1.5);axis([0 0.0051 -1.2 1.2]);
xlabel('Time (seconds)');ylabel('Amplitude');title('DSBSC signal');
grid on;
%%%% Spectrum of DSBSC
subplot(3,2,6);
plot(f,abs(SF/max(SF)),'m','Linewidth',2); axis([-2*fc 2*fc -0.1 1.1]);
xlabel('f'); ylabel('Magnitude|'); title('Spectrum of DSBSC');
grid on
%Power Calculations
16. mu1=am1/ac;
mu2=am2/ac;
mu=sqrt((mu1^2)+(mu2^2)); %Modulation index
Pc=(ac^2)/2 %Carrier Power
Pu=Pc*(mu^2)/4 %USB POWER
Pl=Pc*(mu^2)/4 %LSB POWER
Ps=Pu+Pl %Total Side Band Power
Pt=Pc*(1+((mu^2)/2)); %Total Power of Modulated wave
%NOISE ADDED
%DSB-SC signal with 10db noise
y3=awgn(st,10);
figure();
subplot(4,2,1);
plot(t,y3/max(y3), 'black', 'LineWidth',1.5);axis([0 0.005 -1.2 1.2]);
xlabel('Time (seconds)');ylabel('Amplitude');title('s(t) +10dB noise');
grid on;
%Spectrum of DSB-SC 10db noise added
Y3F=abs((2/N)*fftshift(fft(y3)));
subplot(4,2,2);
plot(f,Y3F/max(Y3F), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude(Volts)');title('Spectrum of 10db
Noise Modulated signal');
grid on;
%DSB-SC signal with 20db noise
y4=awgn(st,20);
subplot(4,2,3);
plot(t,y4/max(y4), 'black', 'LineWidth',1.5);axis([0 0.005 -1.2 1.2]);
xlabel('Time (seconds)');ylabel('Amplitude');title('s(t) +20dB noise');
grid on;
%Spectrum of DSB-SC 20db noise added
Y4F=abs((2/N)*fftshift(fft(y4)));
subplot(4,2,4);
plot(f,Y4F/max(Y4F), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude(Volts)');title('Spectrum of 20db
Noise Modulated signal');
grid on;
%DSB-SC signal with 30db noise
y5=awgn(st,30);
subplot(4,2,5);
plot(t,y5/max(y5), 'black', 'LineWidth',1.5);axis([0 0.005 -1.2 1.2]);
xlabel('Time (seconds)');ylabel('Amplitude');title('s(t) +30dB noise');
grid on;
%Spectrum of DSB-SC 30db noise added
Y5F=abs((2/N)*fftshift(fft(y5)));
subplot(4,2,6);
plot(f,Y5F/max(Y5F), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude(Volts)');title('Spectrum of 30db
Noise Modulated signal');
grid on;
%DSB-SC signal with 40db noise
y6=awgn(st,40);
subplot(4,2,7);
plot(t,y6/max(y6), 'black', 'LineWidth',1.5);axis([0 0.005 -1.2 1.2]);
xlabel('Time (seconds)');ylabel('Amplitude');title('s(t) +40dB noise');
grid on;
%Spectrum of DSB-SC 40db noise added
Y6F=abs((2/N)*fftshift(fft(y6)));
subplot(4,2,8);
plot(f,Y6F/max(Y6F), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude(Volts)');title('Spectrum of 40db
Noise Modulated signal');
17. grid on;
%%%%%%DEMODULATION USING COASTAS LOOP%%%%%%%
% DSB-SC signal
% -----------------------------------------------------------------------
% ---------------------------RECEIVER PART-------------------------------
N = length(y6);
t = 0:1:N-1; % Time vector
phi = zeros(1,N); % Phase vector of VCO initialize
s1 = zeros(1,N);
s2 = zeros(1,N);
y1 = zeros(1,N);
y2 = zeros(1,N);
for i = 1:N
if i>1
% The step in which phase is changed is pi*5*10*-5, it can be varied.
phi(i) = phi(i-1) - (5*10^-5)*pi*sign(y1(i-1)*y2(i-1));
end
s1(i) = st(i) * cos(2*pi*fc*t(i)/fs + phi(i));
s2(i) = st(i) * sin(2*pi*fc*t(i)/fs + phi(i));
% -----------------------INTEGRATOR------------------------------------
if i<=100
% If sample index is less than 100 (Tc/Ts) then we sum available previous
% samples
for j=1:i
y1(i) = y1(i) + s1(j);
y2(i) = y2(i) + s2(j);
end
else
% Summing previous 100 (Tc/Ts) values
for j = i-99:i
y1(i) = y1(i) + s1(j);
y2(i) = y2(i) + s2(j);
end
end
%----------------------------------------------------------------------
end
%Time domain of Demodulated signal
figure();
subplot(1,2,1);
plot(t,y1);title('Demodulated signal');axis([0 1000 -50 50]);
xlabel('Time');ylabel('Amplitude');
%frequency domain of Demodulated signal
Y1F=abs((2/N)*fftshift(fft(y1)));
subplot(1,2,2);
plot(f,Y1F/max(Y1F), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude');title('Spectrum of Demodulated
signal');
grid on;
18.
19. Pc = 0.5000 Pu = 0.7813 mu = 2.5000
Pl = 0.7813 Ps = 1.5625 Pt = 2.0625
Base BandSignal Modulation and Demodulation:
Baseband modulation and demodulation techniques are fundamental to vg voice, video). If we
consider the voice signal then voice signal band is approximately 4kHz. That means voice
signal contains frequencies ranging from 0-4kHz.
What is Modulation? Modulation is basically increasing signal frequency someway. This
means voice base band is 4kHz and uplifting voice signal frequency to let u say, 1900kHz.
Now, question is wny we need to uplift frequency of actual baseband signal? And here radio
transmission basic concept comes into picture.
In very simple way length of antenna used to transmit signal is directly related to signal
wavelength. Wavelength is length of single cycle of signal. And then what is
frequency? Frequency is number of cycles of signal per second, or, inverse of time taken
to complete one cycle. So, what we can deduce here is if frequency of signal is high then wave
length of signal will be short and vice versa.
relation between frequency and wavelength is expressed by,
c = f * λ
where c = velocity of light which is approximately 3×10^8 m/s , f = frequency of signal, and λ
= wavelength of signal.
20. Task4:Generate bandlimited signal for the frequency range 300 to 3400 Hz. Repeat the
above Tasks for this signal.
MATLAB CODE FOR TASK-4
clear all; close all; clc;
fs=30000;
Ts=1/fs;
N=5000;
f=(-N/2:1:N/2-1)*fs/N;
fc=5000;%carrier frequency
fs=30000;%Sample frequency
N=5000;%Number of samples
ac=1;
am1=1;
am2=1;
am3=1;
am4=1;
am5=1;
am6=1;
am7=1;
am8=1;
Ts=1/fs; % Sampling interval
t=(0:Ts:(N*Ts)- Ts);
b=300;
a=3400;
%Unmodulated carrier
c = cos(2*pi*fc*t);
% Message signal
m1=
cos(2*pi*200*t)+cos(2*pi*500*t)+cos(2*pi*700*t)+cos(2*pi*1000*t)+cos(2*pi*1
500*t)+cos(2*pi*2000*t)+cos(2*pi*3000*t)+cos(2*pi*34000*t);
[b,a] = butter(5,fc*2/fs);
m = filtfilt(b,a,m1);
%%% Spectrum of Message signal
M= abs((2/N)*fftshift(fft(m)));
%%%% Generation of carrier signal
c = cos(2*pi*fc*t);
%%% Spectrum of Carrier signal
C= abs((2/N)*fftshift(fft(c)));
figure(1);
%%%% Message signal
subplot(2,2,1);
plot(t,m/max(m), 'black', 'LineWidth',1.5);axis([0 0.005 -1.2 1.2]);
xlabel('Time (seconds)');ylabel('Amplitude');title('message signal');
grid on;
%%%% Spectrum of Message signal
subplot(2,2,2);
plot(f,abs(M/max(M)),'r','Linewidth',2); axis([-8000 8000 -0.001 1.2]);
xlabel('f'); ylabel('Magnitude|'); title('Spectrum of Message Signal');
grid on
%%%% Carrier signal
subplot(2,2,3);
plot(t,c/max(c), 'b', 'LineWidth',1.5);axis([0 0.0051 -1.2 1.2]);
xlabel('Time (seconds)');ylabel('Amplitude');title('Carrier Signal');
grid on;
21. %%%% Spectrum of Carrier Signal
subplot(2,2,4);
plot(f,abs(C/max(C)),'m','Linewidth',2); axis([-8000 8000 -0.01 1.2]);
xlabel('f'); ylabel('Magnitude|'); title('Spectrum of carrier Signal');
grid on
% Representation of the DSBSC Signal
figure();
st=2.*m.*cos(2*pi*fc*t);
SF= abs((2/N)*fftshift(fft(st)));
%%%% DSBSC signal
subplot(1,2,1);
plot(t,st/max(st), 'b', 'LineWidth',1.5);axis([0 0.0051 -1.2 1.2]);
xlabel('Time (seconds)');ylabel('Amplitude');title('DSBSC signal');
grid on;
%%%% Spectrum of DSBSC
subplot(1,2,2);
plot(f,abs(SF/max(SF)),'m','Linewidth',2); axis([-8000 8000 -0.01 1.2]);
xlabel('f'); ylabel('Magnitude|'); title('Spectrum of DSBSC');
grid on
%Power Calculations
mu1=am1/ac;
mu2=am2/ac;
mu3=am3/ac;
mu4=am4/ac;
mu5=am5/ac;
mu6=am6/ac;
mu7=am7/ac;
mu8=am8/ac;
mu=sqrt((mu1^2)+(mu2^2)+(mu3^2)+(mu4^2)+(mu5^2)+(mu6^2)+(mu7^2)+(mu8^2));
%Modulation index
Pc=(ac^2)/2 %Carrier Power
Pu=Pc*(mu^2)/4 %USB POWER
Pl=Pc*(mu^2)/4 %LSB POWER
Ps=Pu+Pl %Total Side Band Power
Pt=Pc*(1+((mu^2)/2)) %Total Power of Modulated wave
%NOISE ADDED
%DSB-SC signal with 10db noise
y3=awgn(st,10);
figure();
subplot(4,2,1);
plot(t,y3/max(y3), 'black', 'LineWidth',1.5);axis([0 0.005 -1.2 1.2]);
xlabel('Time (seconds)');ylabel('Amplitude');title('s(t) +10dB noise');
grid on;
%Spectrum of DSB-SC 10db noise added
Y3F=abs((2/N)*fftshift(fft(y3)));
subplot(4,2,2);
plot(f,Y3F/max(Y3F), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude(Volts)');title('Spectrum of 10db
Noise Modulated signal');
grid on;
%DSB-SC signal with 20db noise
y4=awgn(st,20);
subplot(4,2,3);
plot(t,y4/max(y4), 'black', 'LineWidth',1.5);axis([0 0.005 -1.2 1.2]);
xlabel('Time (seconds)');ylabel('Amplitude');title('s(t) +20dB noise');
grid on;
%Spectrum of DSB-SC 20db noise added
Y4F=abs((2/N)*fftshift(fft(y4)));
subplot(4,2,4);
plot(f,Y4F/max(Y4F), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
22. xlabel('Frequency (Hz)');ylabel('Amplitude(Volts)');title('Spectrum of 20db
Noise Modulated signal');
grid on;
%DSB-SC signal with 30db noise
y5=awgn(st,30);
subplot(4,2,5);
plot(t,y5/max(y5), 'black', 'LineWidth',1.5);axis([0 0.005 -1.2 1.2]);
xlabel('Time (seconds)');ylabel('Amplitude');title('s(t) +30dB noise');
grid on;
%Spectrum of DSB-SC 30db noise added
Y5F=abs((2/N)*fftshift(fft(y5)));
subplot(4,2,6);
plot(f,Y5F/max(Y5F), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude(Volts)');title('Spectrum of 30db
Noise Modulated signal');
grid on;
%DSB-SC signal with 40db noise
y6=awgn(st,40);
subplot(4,2,7);
plot(t,y6/max(y6), 'black', 'LineWidth',1.5);axis([0 0.005 -1.2 1.2]);
xlabel('Time (seconds)');ylabel('Amplitude');title('s(t) +40dB noise');
grid on;
%Spectrum of DSB-SC 40db noise added
Y6F=abs((2/N)*fftshift(fft(y6)));
subplot(4,2,8);
plot(f,Y6F/max(Y6F), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude(Volts)');title('Spectrum of 40db
Noise Modulated signal');
grid on;
%%%%%%DEMODULATION USING COASTAS LOOP%%%%%%%
% DSB-SC signal
% -----------------------------------------------------------------------
% ---------------------------RECEIVER PART-------------------------------
N = length(y6);
t = 0:1:N-1; % Time vector
phi = zeros(1,N); % Phase vector of VCO initialize
s1 = zeros(1,N);
s2 = zeros(1,N);
y1 = zeros(1,N);
y2 = zeros(1,N);
for i = 1:N
if i>1
% The step in which phase is changed is pi*5*10*-5, it can be varied.
phi(i) = phi(i-1) - (5*10^-5)*pi*sign(y1(i-1)*y2(i-1));
end
s1(i) = st(i) * cos(2*pi*fc*t(i)/fs + phi(i));
s2(i) = st(i) * sin(2*pi*fc*t(i)/fs + phi(i));
% -----------------------INTEGRATOR------------------------------------
if i<=100
% If sample index is less than 100 (Tc/Ts) then we sum available previous
% samples
for j=1:i
y1(i) = y1(i) + s1(j);
y2(i) = y2(i) + s2(j);
end
else
% Summing previous 100 (Tc/Ts) values
for j = i-99:i
y1(i) = y1(i) + s1(j);
y2(i) = y2(i) + s2(j);
23. end
end
%----------------------------------------------------------------------
end
%Time domain of Demodulated signal
figure();
subplot(1,2,1);
plot(t,y1);title('Demodulated signal');axis([100 300 -100 100]);
xlabel('Time');ylabel('Amplitude');
%frequency domain of Demodulated signal
Y1F=abs((2/N)*fftshift(fft(y1)));
subplot(1,2,2);
plot(f,Y1F/max(Y1F), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude');title('Spectrum of Demodulated
signal');
grid on;
mu = 2.8284 Pc = 0.5000 Pu = 1.0000
Pl = 1.0000 Ps = 2.0000 Pt = 2.5000
24. Task5:Repeat above tasks for real speech signals.
MATLAB CODE FOR TASK-5
clear all; close all; clc;
fc=5000; %carrier frequency
fs=30000; %Sample frequency
N=5000; %Number of samples
Ts=1/fs; %Sampling interval
t=(0:Ts:(N*Ts)- Ts); %TIME INTERVAL
f=(-N/2:1:N/2-1)*fs/N; %FREQUENCY INTERVAL
ac=1; %Peak Amplitude of Carrier Signal
% Speech signal
[m, fs] = audioread('speech.wav');
m = m(35001:40000); m = m';m = m/max(m);
25. M=abs((2/N)*fftshift(fft(m))); %%% Spectrum of Message signal
c = ac.*cos(2*pi*fc*t); %%%% Generation of carrier signal
C=abs((2/N)*fftshift(fft(c))); %%%%Spectrum of Carrier signal
st=2.*m.*cos(2*pi*fc*t); %%%%Representation of the DSBSC Signal
SF=abs((2/N)*fftshift(fft(st))); %%%%Spectrum of the DSBSC Signal
figure();
%%%% Message signal
subplot(3,2,1);
plot(t,m/max(m), 'black', 'LineWidth',1.5);axis([0 0.005 -2.5 2.5]);
xlabel('Time (seconds)');ylabel('Amplitude');title('500 Hz message
signal');
grid on;
%%%% Spectrum of Message signal
subplot(3,2,2);
plot(f,abs(M/max(M)),'r','Linewidth',2); axis([-2*fc 2*fc -0.1 1.1]);
xlabel('f'); ylabel('Magnitude|'); title('Spectrum of Message Signal');
grid on
%%%% Carrier signal
subplot(3,2,3);
plot(t,c/max(c), 'b', 'LineWidth',1.5);axis([0 0.005 -2.5 2.5]);
xlabel('Time (seconds)');ylabel('Amplitude');title('Carrier Signal');
grid on;
%%%% Spectrum of Carrier Signal
subplot(3,2,4);
plot(f,abs(C/max(C)),'m','Linewidth',2); axis([-2*fc 2*fc -0.1 1.1]);
xlabel('f'); ylabel('Magnitude|'); title('Spectrum of carrier Signal');
grid on
%%%% DSBSC signal
subplot(3,2,5);
plot(t,st/max(st), 'b', 'LineWidth',1.5);axis([0 0.0051 -1.2 1.2]);
xlabel('Time (seconds)');ylabel('Amplitude');title('DSBSC signal');
grid on;
%%%% Spectrum of DSBSC
subplot(3,2,6);
plot(f,abs(SF/max(SF)),'m','Linewidth',2); axis([-2*fc 2*fc -0.1 1.1]);
xlabel('f'); ylabel('Magnitude|'); title('Spectrum of DSBSC');
grid on
%Power Calculations
Pc=(ac^2)/2 %Carrier Power
%NOISE ADDED
%DSB-SC signal with 10db noise
y3=awgn(st,10);
figure();
subplot(4,2,1);
plot(t,y3/max(y3), 'black', 'LineWidth',1.5);axis([0 0.005 -1.2 1.2]);
xlabel('Time (seconds)');ylabel('Amplitude');title('s(t) +10dB noise');
grid on;
%Spectrum of DSB-SC 10db noise added
Y3F=abs((2/N)*fftshift(fft(y3)));
subplot(4,2,2);
plot(f,Y3F/max(Y3F), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude(Volts)');title('Spectrum of 10db
Noise Modulated signal');
grid on;
%DSB-SC signal with 20db noise
y4=awgn(st,20);
subplot(4,2,3);
plot(t,y4/max(y4), 'black', 'LineWidth',1.5);axis([0 0.005 -1.2 1.2]);
xlabel('Time (seconds)');ylabel('Amplitude');title('s(t) +20dB noise');
grid on;
%Spectrum of DSB-SC 20db noise added
26. Y4F=abs((2/N)*fftshift(fft(y4)));
subplot(4,2,4);
plot(f,Y4F/max(Y4F), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude(Volts)');title('Spectrum of 20db
Noise Modulated signal');
grid on;
%DSB-SC signal with 30db noise
y5=awgn(st,30);
subplot(4,2,5);
plot(t,y5/max(y5), 'black', 'LineWidth',1.5);axis([0 0.005 -1.2 1.2]);
xlabel('Time (seconds)');ylabel('Amplitude');title('s(t) +30dB noise');
grid on;
%Spectrum of DSB-SC 30db noise added
Y5F=abs((2/N)*fftshift(fft(y5)));
subplot(4,2,6);
plot(f,Y5F/max(Y5F), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude(Volts)');title('Spectrum of 30db
Noise Modulated signal');
grid on;
%DSB-SC signal with 40db noise
y6=awgn(st,40);
subplot(4,2,7);
plot(t,y6/max(y6), 'black', 'LineWidth',1.5);axis([0 0.005 -1.2 1.2]);
xlabel('Time (seconds)');ylabel('Amplitude');title('s(t) +40dB noise');
grid on;
%Spectrum of DSB-SC 40db noise added
Y6F=abs((2/N)*fftshift(fft(y6)));
subplot(4,2,8);
plot(f,Y6F/max(Y6F), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude(Volts)');title('Spectrum of 40db
Noise Modulated signal');
grid on;
%%%%%%DEMODULATION USING COASTAS LOOP%%%%%%%
% DSB-SC signal
% -----------------------------------------------------------------------
% ---------------------------RECEIVER PART-------------------------------
N = length(y6);
t = 0:1:N-1; % Time vector
phi = zeros(1,N); % Phase vector of VCO initialize
s1 = zeros(1,N);
s2 = zeros(1,N);
y1 = zeros(1,N);
y2 = zeros(1,N);
for i = 1:N
if i>1
% The step in which phase is changed is pi*5*10*-5, it can be varied.
phi(i) = phi(i-1) - (5*10^-5)*pi*sign(y1(i-1)*y2(i-1));
end
s1(i) = st(i) * cos(2*pi*fc*t(i)/fs + phi(i));
s2(i) = st(i) * sin(2*pi*fc*t(i)/fs + phi(i));
% -----------------------INTEGRATOR------------------------------------
if i<=100
% If sample index is less than 100 (Tc/Ts) then we sum available previous
% samples
for j=1:i
y1(i) = y1(i) + s1(j);
y2(i) = y2(i) + s2(j);
end
else
% Summing previous 100 (Tc/Ts) values
for j = i-99:i
27. y1(i) = y1(i) + s1(j);
y2(i) = y2(i) + s2(j);
end
end
%----------------------------------------------------------------------
end
%Time domain of Demodulated signal
figure();
subplot(1,2,1);
plot(t,y1);title('Demodulated signal');axis([100 300 -100 100]);
xlabel('Time');ylabel('Amplitude');
%frequency domain of Demodulated signal
Y1F=abs((2/N)*fftshift(fft(y1)));
subplot(1,2,2);
plot(f,Y1F/max(Y1F), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude');title('Spectrum of Demodulated
signal');
grid on;
28. Advantages and Disadvantages
Advantages
The advantages of DSB-SC are that power consumption is nominal
The signal can be contained in four sidebands, and the bandwidth is double the amount
in the signal
The modulation system is simple
The advantage of Costas loop compared to PLL is error voltage.
The error voltage is less in Costas loop, due to this synchronization is performed
effectively.
Disadvantages
29. Disadvantage of using a DSB or SSB signal modulation is that it is difficult to recover
information at the receiver.
Demodulation depends upon the carrier present in the received signal at the receiver.
If the carrier is not present, carrier has to be regenerated at the receiver so a complex
circuitry is required.
The Costas loop is having disadvantages of long settling time and instability.
Conclusion
This project mainly deals with DSB-SC carrier acquisition using costas loop.
A Costas loop is a phase-locked loop (PLL) based circuit which is used
for carrier frequency recovery from suppressed-carrier modulation signals
DSB-SC is basically an amplitude modulation wave without the carrier, therefore
reducing power waste, giving it a 50% efficiency. This is an increase compared to
normal AM transmission (DSB), which has a maximum efficiency of 33.333%, since
2/3 of the power is in the carrier which carries no intelligence, and each sideband carries
the same information. Single Side Band (SSB) Suppressed Carrier is 100% efficient.
Future Scope
The future trend is towards giga bit rate transmission. This necessitates for
demodulators of the ground receive system to process faster and handle the ever-rising
data throughput more efficiently. Different Satellites use different modulation schemes
with variable data rates. In order to cater to the Multi mission /Multi satellite data
reception requirements of a ground station, it is necessary to have greater flexibility and
programmability features embedded in the design of demodulators. The Costas loop
technique is very adaptable in future telecommunication techniques as it can be applied
with FPGAs and Software Defined Radios etc.
REFERENCES
Advanced Electronic Communications Systems by Wayne Tomasi