## Forums Search for: Demodulation

## BPSK demodulation

inHi 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...

## FM Demodulation problem (Lyons Ch. 13.22)

inHi all. I've tried to implement an FM demodulation scheme, as suggested by Rick in ch. 13.22 of his 2nd edition (MATLAB code attached at the...

Hi all. I've tried to implement an FM demodulation scheme, as suggested by Rick in ch. 13.22 of his 2nd edition (MATLAB code attached at the end of the post). I have based my approach on Rick's eq. 13-117, but I can't get it to work: - When I don't include the denominator i(n)^2+q(n)^2, I get an instantaneous phase estimate that's close to the "correct" one, but with a sign ...

## AM demodulation using I and Q

inI started a thread re: AM demodulation using I and Q a few weeks ago and I am still having a problem. According to Frerking, AM should...

I started a thread re: AM demodulation using I and Q a few weeks ago and I am still having a problem. According to Frerking, AM should be A=sqrt(i^2+q^2). This works if I tune off the AM zero beat frequency by 1/2 the low pass filter bandwidth. I don't understand this problem. A little more detail: I am using a pair of mixers fed with a sin/cos local osc. to generate I/Q at baseband....

## V.34 demodulation

inHallo everybody, I am just starting a C++ project about V.34 fax demodulation and decoding on PC. In all my previous DSP projects I had an...

Hallo everybody, I am just starting a C++ project about V.34 fax demodulation and decoding on PC. In all my previous DSP projects I had an analog front-end which provided me the baseband samples, or I could recovery them in some other tricky way (e.g. FFT in narrow-band OFDM systems). Anyway, all my processing ever took place at baseband. In this case, on the contrary, my input is a digit...

## AM digital demodulation methods

inHi, I'm having trouble understanding the similarities/differences/advantages of various AM digital demodulation methods, which makes me incapable...

Hi, I'm having trouble understanding the similarities/differences/advantages of various AM digital demodulation methods, which makes me incapable of deciding what to use. I would like to go throug a few methods here and here your thoughts. First, I assume the common goal of all those techniques is to shift the carrier back down to DC and there are a few ways to do this that have different beh...

## Blind demodulation of things like V.34

inHi all, I have never implemented blind demodulation of QAM, and seen all the problems first hand. However, the material I have seen on the...

Hi all, I have never implemented blind demodulation of QAM, and seen all the problems first hand. However, the material I have seen on the subject is all based on despinning the constellation by looking for the corners of a square (or squarish) array sticking out. In schemes like V.34 where the constellation has been completely rounded, to avoid high energy states, are there any pract...

## software demoduation

inHi all, I am new to much of this, so thanks in advance for your patience. Where can you find C++ (or C or C#) source code for ASK, FSK, PSK,...

Hi all, I am new to much of this, so thanks in advance for your patience. Where can you find C++ (or C or C#) source code for ASK, FSK, PSK, QAM, PPM, and BPSK demodulation schemes? I have a feeling that if they exist they won't be free, but that's a problem for another day...Matlab and LabView have great modulation/demodulation toolkits, but we are looking for source code. Thanks again--Ni...

## SDR - Demodulation of DVB-C

inHi, I am having some issues with the IQ-demodulation of a DVB-C signal. Even though it works fine on synthesized data, I can't get the timing...

Hi, I am having some issues with the IQ-demodulation of a DVB-C signal. Even though it works fine on synthesized data, I can't get the timing recovery to work on real data. Can anybody tell me what I am doing wrong or where the problem is most likely to occur? Transmitter: Transmits symbols at 4.5 Msymbols/s with a certain carrier frequency and modulates it with QAM-16. Receiver: ...

## Fax signals demodulation

inDear friends, I'm trying to develope a PC application to receive and send faxes using ula samples of telephone channel. Can any one help me...

Dear friends, I'm trying to develope a PC application to receive and send faxes using ula samples of telephone channel. Can any one help me to find some usefule guides, trial applications, sources, ... on demodulation of V.21, V.27ter and V.29 signals? Thanks in Advance This message was sent using the Comp.DSP web interface on www.DSPRelated.com

## modulation/demodulation - orthogonal fonctions

inHi all, Im working on an (synthetic) acoustic experiment: I have a receiver that records waves emitted by two sources S1 and S2. So the...

Hi all, Im working on an (synthetic) acoustic experiment: I have a receiver that records waves emitted by two sources S1 and S2. So the receiver records R=S1+S2. I would like to "filter" R to get only S1 or S2. Is there any way of doing that ?? S1 and S2 are defined in the same frequency band. So i cannot use a simple filter. Im thinking about modulating/demodulation the signals ...

## xr2211 & non coherent fsk demodulation

inHello, I am using the XR 2211 to demodulate a non coherent fsk signal. It works but I would like to know how to evaluate the theoritical...

Hello, I am using the XR 2211 to demodulate a non coherent fsk signal. It works but I would like to know how to evaluate the theoritical BER performance of this demodulation. But all the non coherent fsk receivers that are mentionned on the web dont use a pll ... any idea ? thank you very much jean michel

## Demodulation with Hilberttransformation

inHello, Using " highpass | rectify | lowpass | downsample" for ages to demodulate signald, I've just found that demodulation using...

Hello, Using " highpass | rectify | lowpass | downsample" for ages to demodulate signald, I've just found that demodulation using Hilberttransformation seems to be very easy (speaking matlab/octave): function y=demodulate( x ) y=sqrt(x.^2 + real(hilbert(x)).^2); endfunction (I implemented "hilbet" myself, using fft) That's the "how", easy ;) But I do not understand the "why". I u...

## OFDM, symbol/phase synchronization, demodulation

inHello, 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

inHi,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...

## Carrier recovery for FSK demodulation

inHi everbody, I'm new in the field of "synchonization" concerning all-digital receivers. At the moment I'm working at the problem of...

Hi everbody, I'm new in the field of "synchonization" concerning all-digital receivers. At the moment I'm working at the problem of "frequency offset correction". While there is a frequency offset between the LO of the transmitter and the LO of the receiver, I've to determine the offset due to perform a proper convertion of the received signal into complex baseband for demodulation. (I'd l...

## Classic FM Demodulation, using Matlab

inI've got a real voltage versus time waveform (e.g. xr) of a carrier frequency that is FM modulated. I need to see the modulation waveform...

I've got a real voltage versus time waveform (e.g. xr) of a carrier frequency that is FM modulated. I need to see the modulation waveform to determine its peak-to-peak amplitude. While I do see a lot of code online for FM demodulation, I'm hesitant to use it unless I can understand it from first principles. The method that makes most sense to me is the equation I see in Rick Lyon's excellent book ...

## Gbps BPSK demodulation

inHi all, I'm looking for an architecture dedicated to a Gbps BPSK demodulation. I will have I and Q available on a 4 bits ADC @ 3Gbps.. Do...

Hi all, I'm looking for an architecture dedicated to a Gbps BPSK demodulation. I will have I and Q available on a 4 bits ADC @ 3Gbps.. Do you know what is the best archtiecture in regards to this high data rate ? I though about CORDIC perhaps, but I'm not sure it can handle this data rate... What suggestions do you have to start my research ? Thanks

## Complex AM demodulation- simple question

inTo demodulate AM, I use the formula am = sqrt(I*I + Q*Q) I am mixing an AM IF signal to baseband, i.e. carrier plus 2 sidebands. My test signal...

To demodulate AM, I use the formula am = sqrt(I*I + Q*Q) I am mixing an AM IF signal to baseband, i.e. carrier plus 2 sidebands. My test signal is modulated at 800Hz. When I look at the demodulation, it looks OK when I mix perfectly to 0Hz, but as the transmitted signal moves up or down frequency, I end up with 2 frequencies in the demodulated signal. i.e. I get a demodulated signal of 200H...

## FSK coherent demodulation in Rayleigh Fading Channel

inWe know coherent and noncoherent FSK demodulation can be done by using correlator and energy detector. In Fading channel case with noncoherent...

We know coherent and noncoherent FSK demodulation can be done by using correlator and energy detector. In Fading channel case with noncoherent demodulation, we can use the energy detector. But in coherent case, how could we use the channel state information to detect signal..... BFSK: h is the channel fading...x is the transmitted signal...n# is noise in channel# rx1 = hx + n1 rx2 = n2...

## Coherent vs Noncoherent GFSK Demodulation

inHi, I've been working on demodulation of low-deviation GFSK signals similar to Bluetooth, with h=0.3 and BT=0.5. I have two simulations, one...

Hi, I've been working on demodulation of low-deviation GFSK signals similar to Bluetooth, with h=0.3 and BT=0.5. I have two simulations, one using a discriminator plus integrate and dump, and another with a second order PLL. I am computing BER vs Eb/No for each case. In the PLL case, I expect to see a few dB of improvement compared to the discriminator, but I'm not getting that. I'm either...