Multicarrier modulation scheme vs FSK

Started by koolguyuf in comp.dsp14 years ago 9 replies

Hey, What is the difference between multicarrier modulation and FSK (Frequency Shift Keying)? Can OFDM considered to be a hybrid of the...

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

Started by kbc in comp.dsp17 years ago 6 replies

Hi does anyone know why differential encoding of data is done in GSM before modulation ? ( As I understand , this is not to enable...

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

Started by Anonymous in comp.dsp15 years ago 7 replies

What type of hardware is typically used for frequency modulation?

What type of hardware is typically used for frequency modulation?


BPSK demodulation

Started by trung86 in comp.dsp12 years ago 2 replies

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...

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 have a project about QPSK demodulation, but when I recover carrier wave, I only recover sin wave(in_pha...


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

Started by Green Xenon [Radium] in comp.dsp14 years ago 9 replies

Hi: Is Quadrature Frequency Modulation used? What for? AFAIK, Quadrature Amplitude Modulation uses a combo of AM and...

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 Google Search for ?Quadrature Frequency Modulation? on http://www.google.com/search?hl=en&lr=&q=%22Quad...


Digital Modulation Scheme

Started by Charvee in comp.dsp14 years ago 5 replies

Hi! I want to ask what is the best digital modulation scheme used for high speed telephone modems?. Thanks. Charvee

Hi! I want to ask what is the best digital modulation scheme used for high speed telephone modems?. Thanks. Charvee


linear modulation and cpm

Started by kbc in comp.dsp18 years ago 3 replies

Hi, The bandwidth in quadrature modulation is typically assumed to be max(B1,B2) where B1 = bandwidth of I(t) B2 = bw of Q(t) ...

Hi, The bandwidth in quadrature modulation is typically assumed to be max(B1,B2) where B1 = bandwidth of I(t) B2 = bw of Q(t) rf signal = I(t) cos wt + Q(t) sin wt = A(t) cos(wt + phi(t) ) w = carrier frequency It seems to me that for a given amount of phase change happening during a given time, constraining the envelope to remain constant increases the b...


Modulation/Signaling scheme for transfering information over an acoustic channel

Started by John McDermick in comp.dsp10 years ago 41 replies

Which modulation scheme is most suitable for transmitting information (a bitstream) over an acoustic channel? i.e. a loudspeaker outputs...

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 modulation/signaling scheme which is robust with respect to ambient noise in the acoustic channel.


Re: Need som help on QPSK Modulation

Started by Allan Herriman in comp.dsp18 years ago

On 16 Dec 2003 22:14:12 -0800, parth175@yahoo.co.in (Parthasarathy) wrote: > Hello > > I have to perform QPSK Modulation, on a 5...

On 16 Dec 2003 22:14:12 -0800, parth175@yahoo.co.in (Parthasarathy) wrote: > Hello > > I have to perform QPSK Modulation, on a 5 Mbps data using a 70 > Mhz carrier. > Is this possible, Yes. It also sounds reasonable, although if your final Tx frequency is quite high (microwave) and you are using an analog modulator, I suggest starting at a much higher first IF (in upper UHF)


Inverse Modulation?

Started by Yuansheng Wu in comp.dsp16 years ago

While I was reading through the aacPlus decoder code, I wasn't sure what the following function's usage, is this an implementation of the IMDCT?...

While I was reading through the aacPlus decoder code, I wasn't sure what the following function's usage, is this an implementation of the IMDCT? Or something else? Any help is appreciated. Thanks in advance. /* * * \brief Perform complex-valued inverse modulation of the subband * samples stored in rSubband (real part) and iSubband (imaginary * part) and stores the ...


GMSK modulation

Started by ik303 in comp.dsp15 years ago 1 reply

Hello all, I have a few questions concerning GMSK modulation in the GSM physical layer. My simulation is done in MATLAB, processed 148 bits and...

Hello all, I have a few questions concerning GMSK modulation in the GSM physical layer. My simulation is done in MATLAB, processed 148 bits and follows the quadrature baseband implimentation method presented in: http://www.emc.york.ac.uk/reports/linkpcp/appD.pdf. 1. I am not sure that I understand correctly the convolution with the Gaussian filter. What I do is : BT = 0.3; T = (3.69*10...


OFDM, symbol/phase synchronization, demodulation

Started by Sebastian in comp.dsp10 years ago 12 replies

Hello, I recently found myself interested in digital modulation techniques. For a hobby project I plan to implement modulation and...

Hello, I recently found myself interested in digital modulation techniques. For a hobby project I plan to implement modulation and demodulation so I can later test it using soundcards for transmitting little text messages via sound between neighbouring laptops. The main goal is to learn something and have fun -- not to build something useful. I'm sure some of you could provide valuable sug...


BPSK demodulation

Started by Thiago in comp.dsp16 years ago 2 replies

Hi,everyone I'm kind of a newbie in everything relatated to modulation/demodulation and as I am now working with it on Matlab, I'm just...

Hi,everyone I'm kind of a newbie in everything relatated to modulation/demodulation and as I am now working with it on Matlab, I'm just learning it by myself. With the amplitude modulation I get by, but I now have to demodulate a BPSK modukated signal and I don't really know how to do it. What I have is a 847KHz signal (actually it's the side band signal) modulated with what I think is t...


16QAM and 16PSK

Started by Deamon in comp.dsp11 years ago 7 replies

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...

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 IEEE. Thanks


AM modulation

Started by louis in comp.dsp16 years ago 1 reply

Hi there, i was just playing around with the modulation function on Matlab here are the simple commmands I run: ? t = 5; ?...

Hi there, i was just playing around with the modulation function on Matlab here are the simple commmands I run: ? t = 5; ? t=0:0.01:10; ? y=power(sin(pi*t/(2*T)), 0.5); ? mod = modulate(y, 250, 44100, 'am'); ? plot(t, mod) so I wanted to know what I should choose my sampling frequency to be - right now it is set to 44100, but how do I know this is appropriate? When I plot (t,mod), i...


Analog modulation

Started by Vladimir Vassilevsky in comp.dsp16 years ago 26 replies

Given an analog bandlimited signal, is it possible to create a continuous time reversible procedure to reduce the bandwidth without losses?...

Given an analog bandlimited signal, is it possible to create a continuous time reversible procedure to reduce the bandwidth without losses? In the other words, is it possible to create a bandwidth reducing analog modulation? Looks like the answer is no, however I can't make a mathematical proof of this. VLV


FM INDEX OF MODULATION QUESTION

Started by Anonymous in comp.dsp16 years ago 3 replies

Hi, It's recently come to my attention that the FM index of modulation is also the peak phase deviation in radians. This was in regards...

Hi, It's recently come to my attention that the FM index of modulation is also the peak phase deviation in radians. This was in regards to a question about the linear region of phase/frequency detector. My question is (and excuse me if the answer is simple): How can you show that this is indeed the case? A mathematical proof would be interesting. Thanks! ...


BER-SNR for Pulse position position modulation

Started by harrywong in comp.dsp12 years ago 3 replies

Hi all, can anyone share with me the equation for the BER-SNR for PPM modulation? I am trying to study the BER performance for AWGN channel in...

Hi all, can anyone share with me the equation for the BER-SNR for PPM modulation? I am trying to study the BER performance for AWGN channel in matlab. Thanks.


Modulation question

Started by sam in comp.dsp18 years ago 5 replies

Hi we have an RF transmission that has some data modulated into it. The RF is transmitted at just under 1GHz. My question is how can we...

Hi we have an RF transmission that has some data modulated into it. The RF is transmitted at just under 1GHz. My question is how can we find out what the modulation scheme is? we are not sure even if it is analogue or digital, i.e. whether it is AM/FM or FSL/PSK/QAM etc., though suspect probably digital. Can anyone suggest how to find out what the scheme is? thank you sam


Modulation Problem

Started by Texas Longhorns in comp.dsp17 years ago 2 replies

If linear modulation systems are to be compared on an equal peak power basis (all have equal peak signal values), show that: A. SSB has a...

If linear modulation systems are to be compared on an equal peak power basis (all have equal peak signal values), show that: A. SSB has a (S/N)out that is 3 dB better than DSB. B. SSB has a (S/N)out that is 9 dB better than AM. Help with this problem would be greatly appreciated. Thank you in advance.