The design for QAM modulator below is for a standard 16-QAM constellation. The general form of an M-ary signal can be defined as S(t) = sqrt((2*Emin)/Ts)*ai*cos(2πfot) + sqrt((2*Emin)/Ts)*bi*sin(2πfot) Here, Emin is the energy of the signal with lowest amplitude and ai and bi are pair of independent integers chosen according to the location of the particular signal point. Fo is the carrier frequency and Ts is the symbol period. Non-rectangular QAM constellations achieve marginally better bit-error rate (BER) but are harder to modulate and demodulate. Hence, below is the simulation of a rectangular QAM constellation. Simulation model in MATLAB Following is the methodology of simulation of the QAM modulator in MATLAB, 1) Generation of random binary sequence, this is the input which is to be modulated. 2) Assigning group of 4 bits to each 16-QAM constellation symbol per the Gray mapping 3) Addition of white Gaussian Noise 4) Demodulation of 16-QAM symbols Upon reception of the signal, the demodulator examines the received symbol, which may have been corrupted by the channel or the receiver (e.g. additive white Gaussian noise). It selects, as its estimate of what was actually transmitted, that point on the constellation diagram which is closest (in a Euclidean distance sense) to that of the received symbol. Thus it will demodulate incorrectly if the corruption has caused the received symbol to move closer to another constellation point than the one transmitted. The constellation diagram allows a straightforward visualization of this process. 5) De-mapping per decimal to Gray conversion 6) Counting the number of bit errors 7) Running this for each value of SNR so that we can get can arrive at a relation between bit errors and SNR

The block diagram of the QAM simulation model is as shown below,

Code for MATLAB clear;

clc; N = 10^4; % number of symbols M = 16; % constellation size k = log2(M); % bits per symbol % defining the real and imaginary PAM...

...QAM and QPSK:
Aim:
Review of Quadrature Amplitude Modulator (QAM) in digital communication system, generation of Quadrature Phase Shift Keyed (QPSK or 4-PSK) signal and demodulation.
Introduction:
The QAM principle: The QAMmodulator is of the type shown in Figure 1 below. The two paths to the adder are typically referred to as the ‘I’ (inphase), and ‘Q’ (quadrature), arms.
Not shown in Figure 1 is...

...Continuously variable slope delta
Modulator
INTRODUCTION:-
Continuously variable slope delta modulation (CVSD or CVSDM) is a voice coding method. It is a delta modulation with variable step size (i.e. special case of adaptive delta modulation), first proposed by Greefkes and Riemens in 1970.
CVSD encodes at 1 bit per sample, so that audio sampled at 16kHz is encoded at 16kbit/s.
The encoder...

...Analysis of
Design and Simulation of QPSK Modulator for Optic Inter Satellite Communication:Review
Submitted by
A Penchala Bindushree
4th Sem, M.Tech (DCE)
Acharya Institute of Technology
Bangalore – 560090
Under the guidance of
Internal Guide:
Nataraju A B M.tech, (PhD)
Assistant Professor, ECE Department
Acharya Institute of Technology
Bangalore – 560090
External Guide:
Vijesh T V
Scientist/Engineer ‘SC’
LEOS/ISRO
Bangalore-560013
Abstract
We...

...BALANCED RING MODULATOR
Nur Amirah binti Kamaruzaman#1, Nurasmira Wanie binti Abd Wahab#2, Nurul Liana binti Mansor#3,
Bachelor of Electronic Engineering and Computer Engineering (BENE)
1B021110140
2B021110237
3B021110216
Abstract— balanced ring modulator is a type of modulator that the diodes are arranged like a ring. In balanced ring modulator, there are also transformers and the carrier. This type of modulator is like...

...of a sigma-delta modulator of the first order (Figure 4). It includes a difference amplifier, an integrator, and a comparator with feedback loop that contains a 1-bit DAC. (This DAC is simply a switch that connects the negative input of the difference amplifier to a positive or a negative reference voltage.) The purpose of the feedback DAC is to maintain the average output of the integrator near the comparator's reference level.
Figure 4. Block diagram of a sigma-delta...

...EVALUATION OF EFFECTS OF OVARIECTOMY AND TREATMENT WITH ESTROGEN-REPLACEMENT THERAPY OR SELECTIVE ESTROGEN RECEPTOR MODULATORS (SERM) ON VOIDING FUNCTION AND P2X RECEPTOR EXPRESSION IN THE FEMALE RAT
TABLE OF CONTENTS
Abbreviations Page 6
Abstract Page 6
Study 1 Page 10
Introduction Page 10
Menopause and the overactive bladder Page 10
Estrogens for the treatment of OAB in post menopausal women Page 12
SERM and...