## Forums Search for: Modulation

## Max Bit rate question

inIf I have a digital FM system do you have any background on the max bit rate you can achieve for a given depth of modulation? eg for 250kHz...

If I have a digital FM system do you have any background on the max bit rate you can achieve for a given depth of modulation? eg for 250kHz depth of modulation I can achieve only 500kb/s. Does this sound right? This must be pretty basic stuff I am sure and related to Shannons law somewhere. Thanks Tom

## GMSK modulation and its PSD

Hi all I'm working on GMSK modem simulation in MATLAB. I'm almost done with the modulation part albeit i'm not sure if the model I used...

Hi all I'm working on GMSK modem simulation in MATLAB. I'm almost done with the modulation part albeit i'm not sure if the model I used is correct adding to my trouble is the ambiguity with the Power Spectral Density of the GMSK modulated signal (also the MSK modulated signal). Here I'm writing the algorithm I followed to do the simulation: bitrate=4000bps BT=0.3 1.calculated ...

## GMSK modulation and its PSD

inHi all I'm working on GMSK modem simulation in MATLAB. I'm almost done with the modulation part albeit i'm not sure if the model I used...

Hi all I'm working on GMSK modem simulation in MATLAB. I'm almost done with the modulation part albeit i'm not sure if the model I used is correct adding to my trouble is the ambiguity with the Power Spectral Density of the GMSK modulated signal (also the MSK modulated signal). Here I'm writing the algorithm I followed to do the simulation: bitrate=4000bps BT=0.3 1.calculated ...

## FSK modulation problem....

inHi, I want to make fsk modulation. For example my baseband signal is "1010001110". Ones are represent by 2200 hz and zeroes are by 1100 hz. Now I...

Hi, I want to make fsk modulation. For example my baseband signal is "1010001110". Ones are represent by 2200 hz and zeroes are by 1100 hz. Now I know that for generating a fsk signal, I have to generate a signal that shows ones(as callded s1) and another one that shows zeros(as called s0). And when "1" comes, it has to be shown in s1; and when "0" comes, it has to be shown in s0; WHILE it is sho...

## ADC and DAC for modulation and demodulation

inHi I have written Matlab script for BPSK modulation. The way my code works is as follow: series of 0 and 1----> NRZ data (continuous...

Hi I have written Matlab script for BPSK modulation. The way my code works is as follow: series of 0 and 1----> NRZ data (continuous rectangular pulses with amplitude -1 and 1)---> multiply by carrier----> add noise--> multiply by carrier---> integration---> detection---> Bit Error collection? I would like to know can anyone tell me where I should apply DAC and ADC ? I am wondering shoul

## phase ambiguity removal

inHi all, can anybody suggest some technique other than differential encoding or using training sequence to remove phase ambiguity of 180...

Hi all, can anybody suggest some technique other than differential encoding or using training sequence to remove phase ambiguity of 180 degree when using BPSK and phase ambiguity of 90,180,270 when using 4-QAM for modulation. i'm using these modulation schemes for blind detection in MIMO systems , where the received signal has this arbitrary phase ambiguity. any help about this pro...

## Re: modulation, bit rate, lasers and diodes sources

inYet another point: turning a signal source on and off abruptly creates sidebands. The greater the selectivity of the receiver, the slower such...

Yet another point: turning a signal source on and off abruptly creates sidebands. The greater the selectivity of the receiver, the slower such modulation must proceed. Turning an incoherent diode with all its simultaneous frequencies on and off creates even broader sidebands and lowers the available speed. I can't guess the modulation speed that makes this an issue. Jerry

## Re: Beamforming and MRC basics

inI have a very basic question with regards to beam-forming or MRC. When I apply complex weigths for example while doing co-phasing for MRC,...

I have a very basic question with regards to beam-forming or MRC. When I apply complex weigths for example while doing co-phasing for MRC, does this phase rotate my constellation. Everywhere I read , I never see a beamforming effect on the demodulation. Given Im using a PSK kind of modulation,don't these complex weights affect my constellations.After all isnt pSk modulation some form of Sin(wct + ...

## ISDB-T synchronization

Hi, I am doing the synchronization for ISDB-T at the moment. For pure coherent modulation, it is easy to use the embedded SP for fine...

Hi, I am doing the synchronization for ISDB-T at the moment. For pure coherent modulation, it is easy to use the embedded SP for fine timing synchronization since we may use them to estimate the time domain CIR. However, if differential modulation is adopted, there will not be available SP in the frequency domain, in this case, how fine timing sychronization is done? Many thanks eeed

## Overlap-add induces ring-modulation

inHi, I have implemented overlap-add method for granular pitchshifting and eventually I realized, that since the "overlapping" is...

Hi, I have implemented overlap-add method for granular pitchshifting and eventually I realized, that since the "overlapping" is basically multiplying with a hann window or something, it basically is a ring-modulation. I unfortunately verified this on a spectrum analyzer - it added f+m and f-m to the testing frequency. But this means the only way to avoid the ringing is to make the window larger...

## Modulation transfer function

Hi, I have a doubt regarding 1 other project. I have to get the modulation transfer function of an image (and the same image defocused)....

Hi, I have a doubt regarding 1 other project. I have to get the modulation transfer function of an image (and the same image defocused). The defocus is either induced by constructing a bessel filter (similar to airy functions, defocus created by unfocused thin lens). Even though I already designed the filter, I am currently using a webcam to get the defocus by altering the focus of the le...

## Alamouti MIMO simulation works with PSK but not QAM?

inDear All, I'm currently simulating a Alamouti MIMO system to find out the BER for the different number of antennas and different modulation...

Dear All, I'm currently simulating a Alamouti MIMO system to find out the BER for the different number of antennas and different modulation schemes over the Rayleigh fading channel with AWGN for the selected SNR range. I've been using the predefined "modem.pskmod" and "modem.qammod" in matlab for my modulation, demodulation and maximum likelihood decoding. All is working well for the PSK m...

## Few basic doubts in the QPSK modulation & drawing of constellation

inHi, I have a few basic doubts in the QPSK modulation & drawing of constellation, 1) For the QPSK modulation complex signal is required (or)...

Hi, I have a few basic doubts in the QPSK modulation & drawing of constellation, 1) For the QPSK modulation complex signal is required (or) real signal is enough? 2) In the drawing of constellation x-axis is the real value ,y-axis is imaginary & how the angle is represented in the constellation? 3) If the QPSK signal is the complex signal,which formula will suits for the representation...

## Quadrature Modulation tutorial

inI have made a tutorial using flash programs that will help you understand how quadrature modulation and quadrature demodulation works. It is...

I have made a tutorial using flash programs that will help you understand how quadrature modulation and quadrature demodulation works. It is located here: http://www.fourier-series.com/IQMod/index.html I try to show you without getting bogged down in the math. The hope is that after going through the tutorial that the math will be easier to understand. (The math for this stuff can b...

## Coding Gain?

inQUESTION Do you know where I might find tabulated coding gains for different coding schemes? For example BICM, LDPC, MLC, Turbo Codes...

QUESTION Do you know where I might find tabulated coding gains for different coding schemes? For example BICM, LDPC, MLC, Turbo Codes etc. CONTEXT I have been working for a while on different coding schemes, so far I have studied block codes, convolutional codes and trellis coded modulation. I am interested in coding for the bandwidth limited channel, so coded modulation is of more use ...

## Digital modulation - In digital domain or analog..?

inHI, I am new to this group. I have very basic doubt about digital modulation. We modulate the carrier frequency based on the digital input...

HI, I am new to this group. I have very basic doubt about digital modulation. We modulate the carrier frequency based on the digital input values... So is the output of modulator block a digital signal with samples representing the modulated carried signal or is it a modulated continous (analog) signal.. Thanks in advance, arun

## Generating phase modulation.

inHello, As I understand it, phase/frequency modulation is usually achieved by generating by directly modifying the argument of a...

Hello, As I understand it, phase/frequency modulation is usually achieved by generating by directly modifying the argument of a sinusoid. However, if the task was to frequency modulate an existing signal which itself we don't generate, is there a standard way doing so, e.g. by superposing a modulating signal (probably a piecewise continuous signal) on the existing signal? In my case, pha...

## carrier frequency limitations and bandwidth

inHello Forum, Consider a baseband signal of a certain bandwidth B. Using analog modulation (either AM, FM or phase modulation), in a...

Hello Forum, Consider a baseband signal of a certain bandwidth B. Using analog modulation (either AM, FM or phase modulation), in a single channel environment(i.e. not worrying about possible interference between multiple users and channels) can we impress that bandwidth B on carrier of any frequency f? Does the carrier frequency need to be always much larger than the bandwidth of the signal i...

## carrier frequency limitations and bandwidth

Hello Forum, Consider a baseband signal of a certain bandwidth B. Using analog modulation (either AM, FM or phase modulation), in a...

Hello Forum, Consider a baseband signal of a certain bandwidth B. Using analog modulation (either AM, FM or phase modulation), in a single channel environment(i.e. not worrying about possible interference between multiple users and channels) can we impress that bandwidth B on carrier of any frequency f? Does the carrier frequency need to be always much larger than the bandwidth of the signal i...

## (Hamming) windows modulation

inHello, I need help in order to understand what appends in a specify scheme of windows modulation before process FFT (excuse my poor...

Hello, I need help in order to understand what appends in a specify scheme of windows modulation before process FFT (excuse my poor english.. French). 1) When the input signal contain only one spectral "bin" at the middle of the frequecy spectrum, then i modulate the signal with a windows (for example Hamming's windows) before making the FFT. In this case, the spectrum is symetric aro...