## Data Rate, bandwidth

Started by in comp.dsp11 years ago 4 replies

Hi there, I have the following question: 1) For each modulation scheme, there is a corresponding bandwidth efficiency (let's call it n). n =...

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 increasing the bandwidth using the same modulation scheme. 2) If the above equation can not be a...

## Should AWGN be part of a simulation setup that tests Adjacent Channel Interference performance?

Started by in comp.dsp14 years ago 8 replies

Hi there, I'm trying to simulate the adjacent channel(ACI) performance of a continuous phase modulation(CPM) scheme so that I can determine if...

Hi there, I'm trying to simulate the adjacent channel(ACI) performance of a continuous phase modulation(CPM) scheme so that I can determine if my modulator/demodulator meets a particular ETSI performance specification. I'm not sure if my simulation should include AWGN as well as the ACI? Ultimately I'm trying to chose a combination of CPM modulation parameters (alphabet size, pulse shape, pu...

## What waveform[s] do[es] EDT's FSK use?

Started by in comp.dsp13 years ago 6 replies

Hi: What waveform[s] of FSK do[es] the EDT [European Deaf Telephone] protocol use? FSK = Frequency Shift Keying Quote from...

Hi: What waveform[s] of FSK do[es] the EDT [European Deaf Telephone] protocol use? FSK = Frequency Shift Keying Quote from http://www.deaflibrary.org/v18/v18.html : "EDT Operational Mode -- The modulation is frequency shift keyed modulation (i.e. carrier is 10 ms before a character is transmitted and removed 1s after the last character) using Recommendation V.21(1) frequencies. Th...

## Frequency Modulation Spectra

Started by in comp.dsp13 years ago 18 replies

The frequency spectrum of an FM signal with a sinusoidal modulating signal is a discrete infinite frequency series where the carrier and...

The frequency spectrum of an FM signal with a sinusoidal modulating signal is a discrete infinite frequency series where the carrier and sidebands are given by the Bessel functions, which are themselves a function of the modulation index. But when the FM signal is modulated by TWO sinusoidal signals, is the spectrum represented by TWO infinite frequency series? Or is the spectrum mo...

## dithering in 1-bit delta sigma modulators

Started by in comp.dsp15 years ago

Hi Gentle comp.dsp Denizens, The September issue of the JAES has an interesting article on noise power modulation in delta sigma modulators by...

Hi Gentle comp.dsp Denizens, The September issue of the JAES has an interesting article on noise power modulation in delta sigma modulators by Lokken et al. I was wondering if folks agree with his conclusions in section 1.2, where he states essentially that a 1-bit delta sigma modulator will have noise power modulation whether dither is used or not. One thing find odd is that in section ...

## Difference in demodulation of DSB-SC and SSB-SC

Started by in comp.dsp15 years ago 8 replies

hey guys, just wanted to know if any1 could please shred sum light on wat would the differnce in demodulation schemes of double side band...

hey guys, just wanted to know if any1 could please shred sum light on wat would the differnce in demodulation schemes of double side band suppressed carrier and single side band suppressed carrier. This is what i done with matlab coding for modulation and demodulation. 1. DSB-SC: - Modulation: (message signal 500hz) multiply by (carrier frequency 7000hz) ie: cos (2 pi 500 t) x cos (2pi700...

## Dual carrier modulation / signal space diversity : demapping/detection

Started by in comp.dsp16 years ago 1 reply

Hi folks, Can anyone give me some idea about demapping/detection algorithm for Dual carrier modulation . its used in OFDM based UWB...

Hi folks, Can anyone give me some idea about demapping/detection algorithm for Dual carrier modulation . its used in OFDM based UWB systems. DCM is like mapping same databits into different constellation points from different constellation diagrams. In OFDM UWB 4databits are mapped into 2 I/Q points in (16 QAM like constellation) from 2 different constellation digrams. http://www.wi...

## Do we have to use null tones in OFDM modulation?

Started by in comp.dsp13 years ago 4 replies

Hi there, I have a question on OFDM. As we know, most OFDM systems nowadays do not use all the available tones (subcarriers) for data...

Hi there, I have a question on OFDM. As we know, most OFDM systems nowadays do not use all the available tones (subcarriers) for data modulation. Let us say we have 64 tones in total and we might end up with 48 data tones, 4 pilot tones, 3 DC tones and 9 null tones, which is kind of an typical setup. My question is regarding the null tones, which are usually placed on the two boundaries...

## convolutional code

Started by in comp.dsp13 years ago

All, i build two simulink models to watch the benifit of convolutional code. The first one is: Burnoulli bits ----- 16QAM ------...

All, i build two simulink models to watch the benifit of convolutional code. The first one is: Burnoulli bits ----- 16QAM ------ modulation ---- AWGN ----- demodulation. The parameter of 16QAM modulation module is: 'normalizztion method'= average power and 'average power'=1 watt. The parameter of the AWGN channel module is 'Eb/N0'=14.55 and 'input signal power'=1 watt. The BER is about ...

## Modulation scheme with multiple phases and a two amplitudes?

Started by in comp.dsp13 years ago 22 replies

Hi: QAM uses two carrier waves that are 90-degrees out of phases with each each and amplitude-modulates them. QAM only has two phases but can...

Hi: QAM uses two carrier waves that are 90-degrees out of phases with each each and amplitude-modulates them. QAM only has two phases but can have more than two amplitude levels. Is there any modulation scheme that does the opposite -- i.e. the two carrier waves have only two amplitudes but with more than two phases? Thanks, Radium

## Modulation 6 dB margin QPSK-16QAM-64QAM...

Started by in comp.dsp13 years ago 2 replies

Hi, QPSK has - 4 constellation points; 16 QAM -16 constellation points; 64 - 64 constellation points. 16QAM vs QPSK -> Now with the 16...

Hi, QPSK has - 4 constellation points; 16 QAM -16 constellation points; 64 - 64 constellation points. 16QAM vs QPSK -> Now with the 16 possible points in the constellation diagram we have 16 possible symbols. For this 16 symbols we need 4 bits for coding . Compared to the QPSK modulation now we have doubled the transfer rate when using the same symbol clock.But compared to the QPSK, points

## Help: Digital Up Convert(DUC) in FPGA.

Started by in comp.dsp15 years ago 2 replies

Hi, I am trying to implement a Nicam modulator in a fpga. The Nicam modulation is a digital sound modulation of analog TV, and use DQPSK. I...

Hi, I am trying to implement a Nicam modulator in a fpga. The Nicam modulation is a digital sound modulation of analog TV, and use DQPSK. I have some problem when implement the digital up converter(DUC) in fpga. The DUC comprise the cascade of pulse filter, CIC compensation filter CIC filter, and then multiply with carrier generated by a NCO. The interpolator of the pulse filter and ci...

## What is the modulation index?

Started by in comp.dsp13 years ago 4 replies

I have a confusion here. So please help. I have a message signal given as : m(t) = 0.5 cos(wt) + 0.3 sin (2wt) I also have a carrier...

I have a confusion here. So please help. I have a message signal given as : m(t) = 0.5 cos(wt) + 0.3 sin (2wt) I also have a carrier signal whose amplitude is known. and now i want to calculate the modulation index. which is given as amplitude of message signal divided by amplitude of carrier. (Remember that i am doing AM.) The confusion is that: Does the amplitude of message ...

## question about soft symbol mapper

Started by in comp.dsp14 years ago 3 replies

I have came across a so-called soft symbol mapper in OFDM system, which I understand it is modulation by soft values, but how to do it? for...

I have came across a so-called soft symbol mapper in OFDM system, which I understand it is modulation by soft values, but how to do it? for example, QPSK modulation will make [0 0] [0 1] [1 0] [1 1] to [-0.7071-0.7071i] [-0.7071+0.7071i] [+0.7071-0.7071i] [+0.7071+0.7071i], how about soft symbol mapper?

## Bell 103 / v.21 modem emulation software (FSK modutaion with sound card or WAVE file output under DOS or Win32)

Started by in comp.dsp15 years ago 11 replies

I'm looking for some DOS/Win32 software that will emulate a Bell 103 and ITU-T v.21 modem that uses a WAVE format file or a computer's sound...

I'm looking for some DOS/Win32 software that will emulate a Bell 103 and ITU-T v.21 modem that uses a WAVE format file or a computer's sound card for the modulation/demodulation audio signal output/input. These modems use AFSK modulation at 300 baud and 300 bps, at the following frequencies (in Hertz): Bell 103 Originate 1170 = Carrier 1070 = Space (Carrier - 100Hz) 1270 = ...

## why is it working!

Started by in comp.dsp15 years ago 5 replies

Hello, I found that it is believed that if we have an FM modulation then we can demodulate it by calculating (Q/I)' But why? How (sin/cos)'...

Hello, I found that it is believed that if we have an FM modulation then we can demodulate it by calculating (Q/I)' But why? How (sin/cos)' relates to frequency ? Regards

## GFSK help

Started by in comp.dsp14 years ago 1 reply

Hi, Does anyone have a good article/reference/book on Gaussian Minimum/ Frequency Shift Keying modulation and its filter requirement? Many...

Hi, Does anyone have a good article/reference/book on Gaussian Minimum/ Frequency Shift Keying modulation and its filter requirement? Many thx!

## Motor Control paper

Started by in comp.dsp17 years ago 4 replies

I'm looking for anyone that could share with me the following article: An efficient microprocessor-based pulse-width modulator using space...

I'm looking for anyone that could share with me the following article: An efficient microprocessor-based pulse-width modulator using space vector modulation strategy. Thanks in advance

## 8 PSK demodulation

Started by in comp.dsp15 years ago 2 replies

Hi, Is it possible to demodulate the 8 PSK modulation with a differentiel demodulator and without a Costas Loop ? thanks...

Hi, Is it possible to demodulate the 8 PSK modulation with a differentiel demodulator and without a Costas Loop ? thanks...

## 64 QAM

Started by in comp.dsp18 years ago 1 reply

Hi, Anyone knows where to find Matlab source code to simulate 64 QAM modulation/demodulation. Regards, Ren?

Hi, Anyone knows where to find Matlab source code to simulate 64 QAM modulation/demodulation. Regards, Ren?