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 any bandlimiting. In a practical situation this would be implemented either at message level - at the input to each multiplier - and/or at the output of the adder. Probably both ! The motivation for QAM comes from the fact that a DSBSC signal occupies twice the bandwidth of the message from which it is derived. This is considered wasteful of resources. QAM restores the balance by placing two independent DSBSC, derived from message #1 and message #2, in the same spectrum space as one DSBSC. The bandwidth imbalance is removed. In digital communications this arrangement is popular. It is used because of its bandwidth conserving (and other) properties.
It is not used for multiplexing two independent messages. Given an input binary sequence (message) at the rate of n bit/s, two sequences may be obtained by splitting the bit stream into two paths, each of n/2 bit/s. This is akin to a serial-to-parallel conversion. The two streams become the channel 1 and channel...

...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 maintains a reference sample and a step size. Each input sample is compared to the reference sample. If the input sample is larger, the encoder emits a 1 bit and adds the step size to the reference sample. If the input sample is smaller, the encoder emits a 0 bit and subtracts the step size from the reference sample. The encoder also keeps the previous N bits of output (N = 3 or N = 4 are very common) to determine adjustments to the step size; if the previous N bits are all 1s or 0s, the step size is increased. Otherwise, the step size is decreased (usually in an exponential manner, with being in the range of 5 ms). The step size is adjusted for every input sample processed. To allow for bit errors to fade out and to allow (re)synchronization to an ongoing bitstream, the output register (which keeps the reference sample) is normally realized as leaky integrator with a time constant () of about 1 ms.
The decoder reverses this process, starting with the reference sample, and adding or...

...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 bridge modulator. However, the arrangement of the diodes are different from bridge rectifier either in clockwise or anticlockwise. For the operation of the balanced ring modulator, the output of the waveform produce by balanced ring modulator depends on the arrangement of the carrier. This is because the polarity of the carrier will affect the flow of modulating signal through the diodes. The outputs are made up of two signals, one signal shifted up by carrier frequency signal and the other signal is shifted down by frequency carrier. Balanced ring modulators are widely use in musical instrument like guitar and radio receivers.
Keywords— balanced ring modulator, modulating signal, carrier signal, output waveform, amplitude
I. Introduction
We as a group of telecommunication engineer in the established telecommunication company have been invited to participate in one seminar called “Principle Communication...

...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 have proposed a digitally implemented QPSK system for Free-Space Optics systems for future satellite missions. We have used a Laser source of 1550nm wavelength and data rate of 2.5Gbps.The system consists of a modulating and a demodulating block and an advantage of filters added to improve the performance and optimize errors like noise.
The best suited modulator for FSO is Mach-Zehnder modulator which is tuned for high performance. The LiNB03 demodulator demodulates the signal which in turn passed to a filter to attenuate the demodulated output and then through an amplifier to increase the signal strength. Digital approach for implementation of QPSK Modulation is attempted here and compared with existing systems. Simulation and characterization is done to freeze design parameters. The system mainly concentrates on parameter like performance, security, minimum size and cost saving which will be the future of satellite communications.
1. INTRODUCTION
In...

...block diagram 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 modulator. The density of "ones" at the modulator output is proportional to the input signal. For an increasing input the comparator generates a greater number of "ones," and vice versa for a decreasing input. By summing the error voltage, the integrator acts as a lowpass filter to the input signal and a highpass filter to the quantization noise. Thus, most of the quantization noise is pushed into higher frequencies (Figure 5). Oversampling has changed not the total noise power, but its distribution.
3/7
Figure 5. Affect of the integrator in the sigma-delta modulator. If we apply a digital filter to the noise-shaped delta-sigma modulator, it removes more noise than does simple oversampling (Figure 6). This type of modulator (first-order) provides a 9dB improvement in SNR for every doubling of the sampling rate. For higher orders of quantization, we can achieve noise shaping by including more than one...

...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 tamoxifen Page 15
Materials and methods Page 17
Assigning rats into 4 (acute) week and 24 (chronic) week sham and OVX groups and drug treatment groups Page 17
Treatment of ovariectomized rats with subcutaneously-placed slow release pellet of estrogen, progesterone or tamoxifen (SERM) or associated placebo pellet Page 18
Surgical implantation of catheters on sham, OVX and drug treated rats Page 19
Conscious cystometry for sham OVX and drug treated rats Page 20
Statistical Analysis Page 24
Results Page 25
Study 2
Introduction Page 35
P2X receptor involved in bladder function Page 35
P2X receptor in afferent nerve activity Page 36
The role of P2X receptor in humans Page 37
Materials and methods Page 39
Preparation and homogenization of bladder tissue samples and prefiltration
Page 39
RNA purification and cDNA synthesis Page 40
Quntitative PCR (Taqman) Page 41
Results Page 43
Discussion...