Quadrature amplitude modulation

OFDM belongs to a broader class of multicarrier modulation (MCM) in which the data information is carried over many lower rate subcarrier [1]. OFDM is a solution of intersymbol interference (ISI). ISI is caused by dispersive channel. As higher data rate requirement for this OFDM is very important and for the subcarrier modulation using the different type of modulation technique such as Quadrature Amplitude Modulation (QAM) or Phase Shift Modulation (PSK) [3]. The Inverse Fast Fourier Transform (IFFT)

emerges attractive pathway towards future implementation of 1 Tb/s Ethernet systems. This paper proposed the design of 100 Gb/s CO-OFDM system based on the dual polarization of signal. The performance of 100 Gb/s CO-OFDM system using Quadrature Amplitude Modulation (QAM) format transmitted over 576 km optical link using standard SMF is evaluated. The performance of the system in terms of signal-to-noise ratio (SNR), bit error rate (BER), laser linewidth, chromatic dispersion and receiving constellation

Cooperative communication is a new concept of research and it is a powerful technique to mitigate fading in wireless relaying layout. Concerning with the fading problem, this paper is focuses to give a better non-orthogonal space-time block code (STBC) scheme and assimilate it in the cooperative relaying nodes for upgrading performance of the system. Golden coded has also been incorporated in IEEE 802.16 (Wi-MAX) standard as a full rate full diversity space-time code and proven to present a ranking

circumstances or if desired. 8.1.1 Existing Microwave Network The existing microwave network support TDM/ATM and provides a peak downlink of 28 Mbps. Most of the radios existing are PDH and SDH for supporting the legacy 2G and 3G networks. The modulation schemes used are lower in order reaching to a maximum of 128 QAM in smaller channel widths i.e., 7 MHz or 28 MHz. Presently, in India, allotment of carriers for microwave

analogue and then describe in detail of the modulation methods employed in each case. The 2 broadcast radio platforms that will be focused on in this report will be AM/ FM and Digital Radio (DAB); providing background information on each technology and specify modulation methods used by each in

and wavelength reused DWDM passive optical network with Wired/Wireless Services Incorporating OFDM Abstract- In this work, an integrated passive optical network and free space optical communication system based on no-carrier single sideband modulation is proposed. Optical orthogonal frequency multiplexing is employed with dense wavelength division multiplexing to support 16 channels over 300 km bidirectional single mode fiber to enhance spectral efficiency and reduce inter-symbol interference

of multilevel inverter provides several advantages such as high efficiency, low voltage stress, low EMI, better waveform and improved THD. This paper presents the development of Xilinx FPGA as a control circuit for generation of the pulse width modulation (PWM) signal for the single-phase cascaded H-bridge multilevel inverter and modified H-bridge PWM multilevel inverter. The XILINX FPGA based modified multilevel PWM inverter was implemented by adding bi-directional switches to the conventional bridge

Mathematical expressions are: Where G is inverter voltage gain M is modulation index B is boost factor G=M.B= The peak phase voltage of the Z-source inverter is given by 3.3 Maximum Boost Control The disadvantage of Simple Boost Control(SBC) is overcome by introducing the Maximum Boost Control(MBC)

ANGLE MODULATION Chapter Objectives This chapter will help you to: 1. Define and explain the processes of frequency modulation (FM) and phase modulation (PM) and state their differences. 2. Calculate the modulation index given the maximum deviation and maximum modulating frequency, determine the significant number of sidebands in an FM signal, and calculate the bandwidth of an FM signal. 3. Define pre-emphasis and de-emphasis, state their benefits, and show how they are accomplished. 4. Name the

carrier is amplitude modulated what causes the sideband frequencies? - The non-linear mixing of the carrier and intelligence frequencies. 
 4.What determines the bandwidth of emission for an AM transmission? - It is twice the frequency of the highest audio frequency transmitted. The upper sideband is fc +FM where fc is the carrier frequency and FM is the modulation (audio) frequency .The lower sideband is fc – FM. The total bandwidth is 2*FM 5.Explain