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# Discussion Groups > Modulation

Comp.dsp is a worldwide Usenet news group that is used to discuss various aspects of digital signal processing.

We found 1326 threads matching "modulation"

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## Name that modulation... 0

John E. Hadstate - 2008-07-16 16:57:00
Start with logic 0s and 1s. Convert them to pulses that look roughly like Gaussian bell curves each going from near-zero to maximum to near-zero in one bit time, 0s going negative, 1s going positive. Use said negative-and-positive-going pulses to frequency-modulate a carrier. What is th...

## What does PCM mean to you? 0

Jerry Avins - 2005-10-03 15:09:00
PCM stands for pulse code modulation. Can there be PCM without modulation? Is it still PCM if the modulation carries more than one bit per symbol? Radium is confused (or a clever troll), but his ravings raise an interesting question. Jerry -- Engineering is the art of making what you wan...

## Re: Theoretical and practical consequences of groupdelay variation in DMT. 0

julien eyries - 2005-04-19 07:43:00
Hi Morten, Considering DVBT modulation (which is also an OFDM signal), the effect of groupdelay variation over the carriers used by the modulation will result in varying rotations for each of the points in the QAM constellation. => without equalizer , the MER (modulation - error rati...

## Re: What is Pulse Position Modulation? 0

Eric Jacobsen - 2008-12-11 16:03:00
On Thu, 11 Dec 2008 09:26:41 -0600, Vladimir Vassilevsky wrote: > > > Dennis wrote: > > Does anyone know of a good page that describes that Pulse Position > > Modulation PPM is? I am a newbie to modulation. > > Here is what commonly referred as the pulse position modulation: > 1 i...

## Re: How to recognize patterns 0

decious - 2005-09-05 20:21:00
So you have a signal that has some form of modulation on it? Or do you have multiple signals that you need to deinterleave? There are lots of available algorithms for detecting modulation types etc, check out your local IEEE Xplorer, heck even google should produce some. I am not sure what y...

## Amplitude modulation -- misnamed? 0

Steve Pope - 2010-05-02 02:07:00
Shouldn't amplitude modulation really be called "Magnitude Modulation"? After all, in FM, the amplitude is still being modulated, but the magnitude is constant. Or maybe I have too much time on my hands. S. ...

## Data Rate, bandwidth 0

blueyiu - 2007-09-10 07:37:00
Hi there, I have the following question: 1) For each modulation scheme, there is a corresponding bandwidth efficiency (let's call it n). n = R/B where R is the data rate and B is the bandwidth. My question is can I simple say R = n*B no matter how big B is. i.e. can I reach higher data rate by...

## FM modulation 0

senkumar02 - 2005-05-20 09:44:00
hi, i want to take FM modulation to a signal which is changing in its amplitude and frequency. Give me a idea how to start. Thanks, Senthil This message was sent using the Comp.DSP web interface on www.DSPRelated.com ...

## Re: Digital modulation - In digital domain or analog..? 0

Rune Allnor - 2009-09-14 08:23:00
On 11 Sep, 13:37, arun wrote: > HI, > > =A0 =A0I 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 ...

## Re: How does PCM-Demodulation work? 0

glen herrmannsfeldt - 2008-04-28 02:08:00
Randy Yates wrote: (snip) > I'm guessing so. In almost 30 years, I've never heard of a > PCM-demodulator, but I am getting old and senile. Where did you come > across this term? Well, the M is for modulation, but I agree using the term "demodulator" in that case is unusual. In the pa...

## Re: the measure of "wavyness" of signals 0

John Herman - 2006-11-24 23:03:00
This sounds like modulation to me. Have you looked into calculation of the modulation index? If the "wavyness" is modulation, then the proper way to measure the "wavyness" is to pass the signal through a detector appropriate to the type of modulation and measure the statistics of the output ...

## Digital modulation!! 0

santosh nath - 2003-07-07 14:09:00
Hello all, Can anybody tell the key motivation of the inventor (who is the genius behind it?) to use digital modulation instead of its analog counterpart and how did it happen historically and experimentally? Regards, Santosh ...

## What is the best modulation scheme? 0

2005-10-26 02:54:00
Hello all, What kind of modulation scheme that will suit high speed transmission (at least to 1 Gbps)? And obvious choice will be those highly spectral efficient modulation scheme like OFDM. However, if the linearity requirement and the sensitivity to phase noise are very high, then OFDM coul...

## Is QFM ever used? Can it decrease the bandwidth needs of FM video signals? 0

Green Xenon [Radium] - 2007-09-23 19:30:00
Hi: Is Quadrature Frequency Modulation used? What for? AFAIK, Quadrature Amplitude Modulation uses a combo of AM and Phase-Shift-Keying. So QFM would use a combination of FM and PSK. Would this decrease the bandwidth required for broadcasting FM luminance video signals? I did a Googl...

## Symbol rate versus BER question 0

JAlbertoDJ - 2009-11-08 11:59:00
We have two digital modulations, both are the same, the only different is the symbol rate. Usually low symbol rate modulation have less BER than high symbol rate modulation. But my question is if in the case of a bad carrier stability, high symbol rate modulation could have less BER than low s...

## modulation, bit rate, lasers and diodes sources 0

fisico32 - 2011-01-17 07:38:00
Hello Forum, I have a question about the bit rates offered by lasers and diode sources.... A laser source and a diode source of the same central frequency are quite different types of sources. The laser is more collimated, higher power density, much smaller linewidth (bandwidth) which conveys...

Hi, I am looking for matlab source code to simulate adaptive modulation. can anyone help me? regards, Azadeh ...

## 16, 64 non-uniform modulation 0

ahmed2 - 2006-11-22 09:36:00
Hi all can any one tell me how to do 16, 64 non-uniform modulation in matlab,and how to calculate the distance between points, BER Thanks ...

## Modulation transfer function 0

arun - 2007-12-14 13:32:00
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 des...

## Removing modulation of a PAM signal and reconstruction the information 0

darkstar - 2006-09-18 10:40:00
Hi! Using Matlab, I need to send a message through a simulated AWGN channel. I have defined the signal pulse to be a square pulse with different amplitudes depending on the bit, a0 for a 0 and a1 for a 1. I modulate the signal by tx = tx .* cos(2*pi*fmod) where tx is kron(bits,signalpulse). ...

## Re: viterbi traceback - continuous data mode 0

2005-05-18 04:21:00
> Don't forget to compare TCM and BICM. Hi Eric, That's Bit-Interleaved Coded Modulation, right? You mentioned in another thread (august 2004) that "Bit Interleaved Coded Modulation further decouples the system from the modulation and signal processing, and is known to always be as good or b...

## Re: FM demodulation phase unwrapping 0

Jerry Avins - 2007-01-29 11:43:00
cincydsp@gmail.com wrote: ... > You shouldn't need to "unwrap" your phase value, as it shouldn't ever > break out of the [-pi, pi] interval. ... Doesn't that depend on the amount of modulation? I know of nothing inherent in FM (PM, actually) that limits the modulation to any part...

## Detection of Bessel components of a received PM signal 0

mayanksharma - 2009-08-07 12:06:00
Hi My current work involves estimation of modulation index for a PM signal with or without subcarriers. I have found articles to do the same without subcarriers, but I am yet to find something which might work when subcarriers are included. An important method to estimate the modulation index (wh...

niki84 - 2006-04-23 07:27:00
I am working on AD9857 which copmrises an IQ modulator and in fact is a quadrature up convertor Using 14 bits I Q input data , I want to try out various modulation schemes like AM, FSK,FM,BPSK,GMSK, QPSK and QAM. I`ve tried IQ modulation in different (analogue) shchemes with MATLAB using IQ in for...

## Re: What is the analog equivalent of aliasing? 0

Fred Marshall - 2008-05-13 00:16:00
"Green Xenon [Radium]" wrote in message news:4828ded3\$0\$5698\$4c368faf@roadrunner.com... > Hi: > > Aliasing is a digital entity. What is the analog equivalent of aliasing? > Aliasing isn't a digital entity it's a sampling entity. That you digitize the samples has nothing to do wi...

## Re: Fourier of 50 Hz 100% AM of 20 KHz (PWM) ? 0

Cliff Curry - 2004-05-12 20:51:00
The spectrum of a PWM signal is complicated, because PWM is kind of like a frequency or phase modulation. The spectrum depends on exactly how the width of the pulse is determined from the modulation waveform. A width exactly proportional to the amplitude of the samples of the modulation conta...

## Re: What's Es/No mean? 0

Davy - 2006-03-05 02:35:00
Hi john, Thank you for your help! A simple question: Does 10*log10(rate) mean the code gain of BPSK modulation? And is there code gain of QAM modulation? Any suggestions will be appreciated! Best regards, Davy ...

## Multicarrier modulation scheme vs FSK 0

koolguyuf - 2007-01-14 16:56:00
Hey, What is the difference between multicarrier modulation and FSK (Frequency Shift Keying)? Can OFDM considered to be a hybrid of the two? Thanks TD ...

## diff encoding in GSM 0

kbc - 2004-09-06 07:59:00
Hi does anyone know why differential encoding of data is done in GSM before modulation ? ( As I understand , this is not to enable noncoherent detection, but is related to the connection between gmsk and msk which is an offset-PAM modulation. ) shankar ...

## frequency modulation 0

2006-04-25 16:56:00
What type of hardware is typically used for frequency modulation? ...

## Pulse Shaping Question 0

rudykeram - 2013-04-10 22:13:00
Hi, I read two very nice articles about Pulse-Shaping, and they both individually makes a lot of sense, but when I want to draw a conclusion, I get confused. Here is the fist article: http://zone.ni.com/devzone/cda/ph/p/id/200 which in depth explains why pulse shaping is used. So, in this...

## Re: Digital bandwidth 0

glen herrmannsfeldt - 2006-07-30 09:28:00
billoo wrote: > I am currently working on a project which involves determining the > relationship between the the "bandwidth"(as my advisor puts it) and > power consumption of an I/Q transmitter. This might not be related to your question, but I have always found the term "bandwidth"...

## Digital Modulation Scheme 0

Charvee - 2007-12-03 16:01:00
Hi! I want to ask what is the best digital modulation scheme used for high speed telephone modems?. Thanks. Charvee ...

## Calculating BER for optical communications 0

2008-06-03 11:12:00
Hi! I would like to calculate the BER of an optical communications system. The only known value is the total collected intensity as a function of time (I thus can calculate mean intensity, variance,...). The modulation format doesn't matter. The simplest is the best; so we can take OOK mod...

## Modulation/Signaling scheme for transfering information over an acoustic channel 0

John McDermick - 2011-11-09 09:49:00
Which modulation scheme is most suitable for transmitting information (a bitstream) over an acoustic channel? i.e. a loudspeaker outputs the modulated signal and a cell phone microphone picks up the acoustic signal and extracts the information from the modulated signal. I'm looking for a modula...

## Definition of modulation index for shaped FSK 0

Steve Pope - 2010-06-30 17:41:00
I have a pretty elementary question. For an unshaped, 2-FSK signal, the modulation index h is defined as the ratio of the difference between the two tone frequencies to the symbol rate. For shaped 2-FSK, how is h usually defined? I can think of a few possibilities: (1) Base it on the pe...

## modulation: audio DC offset 0

waltech - 2009-12-23 17:39:00
hi a short time ago, I posted I was doing computed modulation. I now have 2 nice sidelobes. The q is this: Where mathematically, and more to the point, where should I account for the necessity in code of doing an DC offset to audio array samples in order to achieve the "Carrier" in AM mod...

## BPSK demodulation 0

trung86 - 2009-12-29 10:23:00
Hi all!! I have implemented BPSK modulation with DSK 6713.I'm writting a program to implement BPSK modulation and demodulation on the same Kit DSK 6713, but it doesn't run. Can we implement BPSK modulation and demodulatio on the same Kit DSP?. I wil post my source code later! By the way! I also hav...

## Linear vs Nonlinear modulation as their carrier recovery algorithm? 0

richard_zhang - 2008-04-01 06:22:00
Dear all, Just found this great forum on DSP. This is my first post and hope someone can help. I am searching for the knowledge on GMSK demodulation and found that some articles say that some carrier/timing recovery algorithms (like Gardner, Early-Late etc) are only applicable to LINEAR modula...

## 16QAM and 16PSK 0

Deamon - 2011-01-07 19:37:00
Please can anyone give me a pointer to a material that does an in depth comparison of the 16QAM and 16PSK modulation in terms of different properties and their SNR vs BER comparison. Any comment about this modulation comparison would be helpful couldn't turn up anything using google and even IE...
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