## modulation schemes

Started by in comp.dsp8 years ago 2 replies

Sirs, For some of the cellular communications standards, multiple modulations schemes are adopted (16QAM, 64QAM etc.). I have feq questions on...

Sirs, For some of the cellular communications standards, multiple modulations schemes are adopted (16QAM, 64QAM etc.). I have feq questions on this, - are these modulation used for modulation of carrier signals or this is baseband related modulation -- assuming this is for carrier modulation, how does the receiver know what modulation has been done used while transmission -- if 16Q...

## baseband modulation (line coding)

Started by in comp.dsp8 years ago 5 replies

I am little unsure about line coding in the digital baseband transmission. I know that in passband modulation, for most cases we do apply...

I am little unsure about line coding in the digital baseband transmission. I know that in passband modulation, for most cases we do apply some pulse-shaping signal to make sure that we are limiting the bandwidth of the symbols before modulation, so that we avoid ISI, and even from spilling to another the adjacent channel in Multi-channel modulation systems. But, I was reading some informatio...

## What does PCM mean to you?

Started by in comp.dsp16 years ago 24 replies

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...

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 want from things you can get. ??????????????????????????????????????????????????????????????????????? ...

## Name that modulation...

Started by in comp.dsp13 years ago 19 replies

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...

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 the name of this type of modulation? If my description of the mechanics of this modulation scheme i...

## What is Pulse Position Modulation?

Started by in comp.dsp13 years ago 5 replies

Does anyone know of a good page that describes that Pulse Position Modulation PPM is? I am a newbie to modulation. Thanks

Does anyone know of a good page that describes that Pulse Position Modulation PPM is? I am a newbie to modulation. Thanks

## Amplitude modulation -- misnamed?

Started by in comp.dsp11 years ago 29 replies

Shouldn't amplitude modulation really be called "Magnitude Modulation"? After all, in FM, the amplitude is still being modulated, but the...

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.

## modulation: audio DC offset

Started by in comp.dsp12 years ago 20 replies

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...

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 modulation ? procedure: I simply add some close sine frequencies to get a 300-3000 hz waveform ( ...

## Strange result of a filter + modulation

Started by in comp.dsp16 years ago

Hello, I am writing a filter ( for pulse shaping ) followed by a modulation ( BPSK ) scheme for a satellite transmission. I...

Hello, I am writing a filter ( for pulse shaping ) followed by a modulation ( BPSK ) scheme for a satellite transmission. I have a result, but I would like to hear your opnion about it. I am using a root raised cosine filter for the input stream, and applying quadrature modulation after it. For instance, suppose I want to transmit this symbol stream ...

## Turbo codes for multi-level modulation

Started by in comp.dsp8 years ago 10 replies

Hi, Turbo codes implementation through BCJR algorithm for binary modulation is straightforward. Can someone inform me about how to do that...

Hi, Turbo codes implementation through BCJR algorithm for binary modulation is straightforward. Can someone inform me about how to do that for multi-level modulation, say QPSK or 16-QAM. Specifically, how does the decoder function. Any reference paper is also welcome. Thanks. _____________________________ Posted through www.DSPRelated.com

## What is the best modulation scheme?

Started by in comp.dsp16 years ago 22 replies

Hello all, What kind of modulation scheme that will suit high speed transmission (at least to 1 Gbps)? And obvious choice will be those...

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 could be out of question especially for system that operate at very high frequency such as 40-70GHz . ...

## choosing the modulation technique

Started by in comp.dsp13 years ago 21 replies

Can I get some feedback on my thought process below for choosing a modulation technique? I am in the process of choosing the modulation and...

Can I get some feedback on my thought process below for choosing a modulation technique? I am in the process of choosing the modulation and coding for the following system: - frequency band: 2 - 20 Hz - bit rate: configurable 2 - 16 bps - transmitter: battery powered - receiver: PC based (i.e. lots of processing power) - channel: some burst noise - adjacent signals/channels: none - traff...

## Fourier series of sign(cos(.)) in simulation and practical mixer simulation

Started by in comp.dsp7 years ago 38 replies

Hi, I simulate (or want to simulate) an RF system. My simulation Nyquist rate is 50GHz, the signals are 8 Msamples long and there is a...

Hi, I simulate (or want to simulate) an RF system. My simulation Nyquist rate is 50GHz, the signals are 8 Msamples long and there is a 5MHz transmission at 1GHz (using standard I/Q modulation). In any case, I am playing around with modulation. When I create a modulation sequence fc = 1GHz + 6.103515624999999kHz % note the non-integer multiple m1(t) = cos(2*pi*fc*t) then...

## FM modulation

Started by in comp.dsp16 years ago 4 replies

hi, i want to take FM modulation to a signal which is changing in its amplitude and frequency. Give me a idea how to...

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

## Is channel code gain independent upon modulation, or not?

Started by in comp.dsp14 years ago 2 replies

Hi, I thought the code gain of one channel code is independent upon modulation, but the simulation in MATLAB/Simulink with...

Hi, I thought the code gain of one channel code is independent upon modulation, but the simulation in MATLAB/Simulink with different modulation shown different codegain. Channelcode: Convolutional, coderate 1/2, memory depth 6, traceback 32, 3bits-softdecision Bitrate after decoder: 20kbit/s 1. FM, with 10khz deviation, 40khz passband before FM-Demodulate, 25khz baseband after FM-Dem...

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

Started by in comp.dsp13 years ago 2 replies

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...

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 modulation scheme. my questions are: 1) what does linear and nonlinear modulation mean? what is the di...

## Watermarking Using Chaotic Modulation

Started by in comp.dsp12 years ago 1 reply

I am doing a project to implement ZERO WATERMARKING (Instead of embedding an external watermark, the zero-watermarking technique extracts...

I am doing a project to implement ZERO WATERMARKING (Instead of embedding an external watermark, the zero-watermarking technique extracts some essential characteristics from the host image and uses them for watermark embedding and extraction). Now for this purpose i am using CHAOTIC MODULATION. In short the steps involved for CHAOTIC MODULATION will be, 1. The original image has been coded i...

## Digital modulation!!

Started by in comp.dsp18 years ago 39 replies

Hello all, Can anybody tell the key motivation of the inventor (who is the genius behind it?) to use digital modulation instead of its...

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

## Symbol rate versus BER question

Started by in comp.dsp12 years ago 14 replies

We have two digital modulations, both are the same, the only different is the symbol rate. Usually low symbol rate modulation have less BER...

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 symbol rate modulation. I think answer is YES, but i am not sure.

Started by in comp.dsp15 years ago

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

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

## 16, 64 non-uniform modulation

Started by in comp.dsp15 years ago

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

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