## Forums Search for: Demodulation

## about the 16qam demodulation in fading channel

inDear all, When I tried to calculate the BER in flat fading channel of 16QAM signals. It is found that the the performance very difficult to...

Dear all, When I tried to calculate the BER in flat fading channel of 16QAM signals. It is found that the the performance very difficult to approach the theoretical values. But in AWGN the demodulation algorithm works well. I found BER in fading channel is very sensitive to the Doppler. Any one can give some direction? Thanks in advance

## Convert demodulation I/Q to soft Data

inI found the signal after demodulation module are Data_I[q:0] and Data_Q[q:0]. How to convert Data_I[q:0] and Data_Q[q:0] to soft...

I found the signal after demodulation module are Data_I[q:0] and Data_Q[q:0]. How to convert Data_I[q:0] and Data_Q[q:0] to soft information Data[q:0]? May you please recommend some references? Any suggestions will be appreciated! Best regards, Robert

## Timing Recovery for Blind Demodulation

inHi! I'm working on a simulation of blind QAM demodulation in Matlab. So far i have implemented AGC, Carrier Phase tracking loop and a CMA...

Hi! I'm working on a simulation of blind QAM demodulation in Matlab. So far i have implemented AGC, Carrier Phase tracking loop and a CMA equalizer - but i have not yet implemented symbol timing recovery. I have seen numerous references to Band-Edge Timiing Recovery (BETR), wich seem to do the trick quite well. I just can't seem to find a lot of information on how it works! I have read "Pass...

## Costas Loop for coherent demodulation of GMSK

inHello, i want do do carrier recovery using costas loop(BPSK based) for coherent demodulation of GMSK. Has anybody tried it? If yes,...

Hello, i want do do carrier recovery using costas loop(BPSK based) for coherent demodulation of GMSK. Has anybody tried it? If yes, please help me out. Thanks and Regards, Sonali

## Change center frequency of I, Q values

inHi All, I use a samplig card with DDC(Digital Down Conversion with quadrature mixer and filter to eliminate frequency at 2*fc) that provides...

Hi All, I use a samplig card with DDC(Digital Down Conversion with quadrature mixer and filter to eliminate frequency at 2*fc) that provides me directly I, Q values of the signal. As the demodulation is performed offline, with the recorded point, the values are not centered around the carrier of interest. I need to track the center frequency of the carrier during the demodulation to compe...

## AM demodulation using MATLAB

inHey all, I am having some trouble with AM demodulation using MATLAB. I used the built-in MATLAB function butter to design a low pass filter and...

Hey all, I am having some trouble with AM demodulation using MATLAB. I used the built-in MATLAB function butter to design a low pass filter and using the transfer function obtained, I filtered the modulated signal multiplied by the carrier. Here's the part of my m-file which deals with it: dam=cos(2*pi*250*t).*am; % am=amplitude modulated signal [b,a]=butter(5,250*2*Ts); %designing low pa...

## AM demodulation from I/Q file SDRSharp

inI have downloaded SDRSharp AM I/Q wav file from web with following attributes: single channel, floating point samples 22050 sample...

I have downloaded SDRSharp AM I/Q wav file from web with following attributes: single channel, floating point samples 22050 sample rate. i got this information about file from audacity software. The SDRSharp demodulates the samples and generate audio from file when it is played in it. I want to demodulate the same using AM demodulation from my software written in C++. i am using from...

## OFDM demodulation question

inHere's my question: In doing the OFDM (like DVB-T) demodulation, why do people just talk about carrier frequency sync and carrier phase noise...

Here's my question: In doing the OFDM (like DVB-T) demodulation, why do people just talk about carrier frequency sync and carrier phase noise but not carrier phase itself? Does that mean OFDM is not coherently demodulated? Thank you for your help! -- Harry

## FM Demodulation to extract Doppler Shift

inGood morning, as part of a masters project I'm currently working on I need to extract the doppler shift from a digital signal in a DSP. So...

Good morning, as part of a masters project I'm currently working on I need to extract the doppler shift from a digital signal in a DSP. So far I'm successfully sampling the signal, which is centered at 4.88kHz with a Doppler shift of about +/- 1.5kHz. Previously I extracted the Doppler Shift using Matlab's "demod" function (FM demodulation) which worked quite well. I now implemented a qua...

## Need Help on Costas Loop for coherent GMSK demodulation

inDear all, I saw in google that costas loop can be used as the carrier recovery mechanism for coherent GMSK signal demodulation, but I did not...

Dear all, I saw in google that costas loop can be used as the carrier recovery mechanism for coherent GMSK signal demodulation, but I did not find any detailed article about it. Can anybody give a good reference to implement costas loop for gmsk? Any useful weblink or technical article will be appreciated. Richard

## DDC a Satellite BPSK signal

inHello, I captured a raw 19.2K BPSK centered at 70 MHz. I want to tune it at 70 MHz and use the real part for BPSK demodulation. In MATLAB...

Hello, I captured a raw 19.2K BPSK centered at 70 MHz. I want to tune it at 70 MHz and use the real part for BPSK demodulation. In MATLAB simulation, I can generate a BPSK modulated with an IF. In FFT plot, I can see the peak of the IF. So if I can tune precisely at IF, I can have a perfect real signal for BPSK demodulation. In the real world, I cannot see the peak of the IF. So how c...

## FM Demodulation - Complex baseband versus Real baseband

inFor FM demodulation, on the face of it, it appears that demodulating it using a real baseband and is no different from using a complex baseband....

For FM demodulation, on the face of it, it appears that demodulating it using a real baseband and is no different from using a complex baseband. The end result is the demodulated baseband. However it would appear that there is probaly an advantage (since most implementations using a DSP describe this method) demodulating using a complex baseband as opposed to a real baseband signal. So w...

## DSSS modulation DQPSK

inHi, I made a complete DSSS demodulator with DBPSK and DQPSK demodulation. In the case of DQPSK demodulation I've got the same PN_code on I...

Hi, I made a complete DSSS demodulator with DBPSK and DQPSK demodulation. In the case of DQPSK demodulation I've got the same PN_code on I and Q branchs. What is the advandatage to put different PN_code on I and Q ? And what is the advantage to make a complex spreading like this : At spreading (modulation) : (I+jQ).(PN_I+jPN_Q) So I signal becomes : I.PN_I-Q.PN_Q and Q signal become...

## complex GMSK demodualtor with knowledge about preamble

Hello, everybody! I have a question about baseband GMSK signal demodulation. For my signal parameters are following: 1) BT=0.3, 2) Symbol...

Hello, everybody! I have a question about baseband GMSK signal demodulation. For my signal parameters are following: 1) BT=0.3, 2) Symbol rate equals sample rate 3) I know preamble sequence I suppose to apply match filter on preamble sequence for timing and frequency offset recovery. Is this method appreciable for baseband GMSK? Can i do something for demodulation having only baseband sig...

## a question about the effect of channel estimation and equalization in ofdm

inin OFDM systems, the LS channel estimation result should be H'=P'/P if we compensate the received data symbols with one tap scheme,...

in OFDM systems, the LS channel estimation result should be H'=P'/P if we compensate the received data symbols with one tap scheme, the equalization result should be D''=D'/H' = P*D'/P'; one the right of the above equation, D'/P' looks like the differential decoding result so the coherent demodulation with LS estimation and onetap equalization sees like the differential demodulation...

## In-band high frequency noise in FM demodulation

inHi all, I have implemented FM demodulation(including Mono and Stereo) on FPGA. When it work on Mono mode, the audio quality sounds good. But...

Hi all, I have implemented FM demodulation(including Mono and Stereo) on FPGA. When it work on Mono mode, the audio quality sounds good. But if I changed the mode to the stereo, the audio quality sounds not very well. I have checked the spectrum of m(t), and there are high noise floor over high frequencies(looks like the response of a high pass filter). Even I changed the differentiator from ...

## How many Noncoherent demodulation methods for CPM are there ?

inand what are the methods? thanks !just tell me some of them,i need to know some Noncoherent demodulation methods for CPM. your help is appreciated !

and what are the methods? thanks !just tell me some of them,i need to know some Noncoherent demodulation methods for CPM. your help is appreciated !

## thx for clay and julius, 'Still mathetical problem, but for AM demodulation with FIR filter"

inClay, thanks for your opinion... my problem is the mathematical equation for how the FIR filter to process demodulation for AM. oya, bout the...

Clay, thanks for your opinion... my problem is the mathematical equation for how the FIR filter to process demodulation for AM. oya, bout the windowing method, u tell me...i found the equation for bandpass filter ideal. i read a book, and i got the equation for unideal filter. is it h=w.hd? h:transfer function unideal w:windowing coef. hd: transfer function ideal filter and do i hav...

## 8 PSK demodulation

inHi, 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

inHi, 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?