To all the guardians of signal processing, iam writing a matlab code for the pulse amplitude modulation and demodulation. i have done in the...

To all the guardians of signal processing, iam writing a matlab code for the pulse amplitude modulation and demodulation. i have done in the following way 1.a sine signal with 1000Hz frequency. 2.then a square wave(carrier) of 10000Hz frequency. 3.multiplied these 2 for sampling. 4.quantized the resultant signal. 5.i have added some noise by using rand() fn. 6.at the receiver side i corr...

Hi all, I m trying to find the modulation schemes and pulse shaping filters most popular in HF communication systems. 1. I figures out that...

Hi all, I m trying to find the modulation schemes and pulse shaping filters most popular in HF communication systems. 1. I figures out that OQPSK, QPSK and FSK are most popular methods and are used in more than 70% of HF comm, while other non-popular methods are M-QAM and M-PSK. Please correct me. 2. I couldnt find any info on pulse shaping though, can an expert direct me to a good referenc...

Hi: What is the maximum amount of bits-per-symbol that can be broadcasted on a telephone line is MFSK [Multiple Frequency Shift Keying] is...

Hi: What is the maximum amount of bits-per-symbol that can be broadcasted on a telephone line is MFSK [Multiple Frequency Shift Keying] is the modulation scheme -- without causing the error rate to get too high? According to wikipedia, if MPSK [Multiple Phase Shift Keying] is used, the maximum bits-per-symbol is 8 Quotes from http://en.wikipedia.org/wiki/Phase-shift_keying#Higher-order...

Hi All, 1) I want to implement MODEM with 128Kbps at 100Khz with high doppler shift channel. Which modulation technique would be suitable...

Hi All, 1) I want to implement MODEM with 128Kbps at 100Khz with high doppler shift channel. Which modulation technique would be suitable . Whether I can go with OFDM or SC-FDMA? Any suggestions 2) Is it possible to simulate 128Kbps with Matlab Thanks & Regards, Ammankumar.S

Hi to all, I'm a student, I'm currently studying: AM, PM, FM, PCM modulation, noise impact on signal etc. I'd like to be able to graphical...

Hi to all, I'm a student, I'm currently studying: AM, PM, FM, PCM modulation, noise impact on signal etc. I'd like to be able to graphical view spectrum of baseband and bandpass signal implicated . I'd like to know, if there is any software, that could help me to be better understand the matter, where I can manually input the function which represent the signal eg. S(t) = Ac [ 1 + cos ( 2 ...

Hi All, I am trying to figure out the *real* motivation behind using MLSE (Maximum Likelihood Sequence Detection) as opposed to a...

Hi All, I am trying to figure out the *real* motivation behind using MLSE (Maximum Likelihood Sequence Detection) as opposed to a symbol-by-symbol detection that maximizes the log-likelihood function. As a tangible example, the standard optimum receiver for CPM (Continuous-Phase Modulation) signals is defined to be a correlator followed by an MLSE detector (Ref. Digital Communications by J...

Hi, My RF hardware accepts IQ data in digital form, and generates the RF signal on the trasmit chain. Similarly on the recieve chain it...

Hi, My RF hardware accepts IQ data in digital form, and generates the RF signal on the trasmit chain. Similarly on the recieve chain it downconverts the signal and generates a digital IQ data. I need to generate the baseband IQ data in the software in the transmit chain and similarly recover the message data from this baseband IQ data. Could some body throw light on how to do this, and if th...

Hi, I'm working on techniques in order to compute center frequency of MAPSK transmission. I foud work based on the computation of the index of...

Hi, I'm working on techniques in order to compute center frequency of MAPSK transmission. I foud work based on the computation of the index of maximum of (fft(s^M)) for MPSK transmission only (M is the modulation order). Are this formula OK for APSK transmission (like 16QAM or 16 APSK). I don't think so because different phase values are used in those cases. Otherwise could you give some help,...

I am designing ofdm equalizer.Ofdm frame contains: -19 symbols -24 subcarriers per channel -pilot symbols that are comb type arranged -BPSK...

I am designing ofdm equalizer.Ofdm frame contains: -19 symbols -24 subcarriers per channel -pilot symbols that are comb type arranged -BPSK modulation The period of one frame (19symbols) is 625us,pilots are inserted every four symbol in time direction and every four subcarrier in frequency direction. I made real measurements to determine the channel nature between base station and rece...

Given a electromagnetic source with a certain carrier frequency, how fast can it be modulated (modulation type aside)? Usually, it is said that...

Given a electromagnetic source with a certain carrier frequency, how fast can it be modulated (modulation type aside)? Usually, it is said that the obtainable bandwidth, by rule of thumb, is around 10% of the carrier frequency...Does anyone know why? the physical reason? In ON-OFF keying, can a pulse be shorter in time than a cycle of the carrier? thanks fisico32

Dear Friends, Till now I am doing on Speech/Audio Coding Implementations on various DSP's. I am thinking to change my domain to Wireless...

Dear Friends, Till now I am doing on Speech/Audio Coding Implementations on various DSP's. I am thinking to change my domain to Wireless Communication, specifically to base band processing and modulation side. I need how to start this? When even I type in the internet I am getting plenty of stuff and don't know what and how to start. I will be glad if any body can give suggestions on thi...

In 3GPP LTE, we use AMC (Adaptive Modulation and coding). It is well known that performance of AMC depends on the speed of UE. Is there any way...

In 3GPP LTE, we use AMC (Adaptive Modulation and coding). It is well known that performance of AMC depends on the speed of UE. Is there any way to track the speed of UE ?

Dear All I am trying to plot histogram of the o/p of equalizer. As the o/p is complex I will have to plot histogram of real and imaginary...

Dear All I am trying to plot histogram of the o/p of equalizer. As the o/p is complex I will have to plot histogram of real and imaginary part separately. I know it is straight forward in matlab, but the problem is how to normalize y-axis. The modulation I am using is 4-QAM. As this will be bimodal distribution around +1 and -1, I am thinking to do following: 1. find std deviation (\sigma...

i have a small doubt .. what do you mean by a estimate of a filter and estimate of a channel? And what is the use of modulation of a filter...

i have a small doubt .. what do you mean by a estimate of a filter and estimate of a channel? And what is the use of modulation of a filter with a DFT or cosine etc? Please help me geeks. .

Hi everyone, I am trying to write a base band simulation of BPSK,QPSK and 16-QAM modulator(using only constellation points coordinates). I...

Hi everyone, I am trying to write a base band simulation of BPSK,QPSK and 16-QAM modulator(using only constellation points coordinates). I figured out from wikipedia.org and "Digital Modulation Technique" that for BPSK the points will have following coordinates(in the complex plane): (+-sqrt(Eb),0)

Hi everyone, I am trying to write a base band simulation of BPSK,QPSK and 16-QAM modulator(using only constellation points coordinates). I...

Hi everyone, I am trying to write a base band simulation of BPSK,QPSK and 16-QAM modulator(using only constellation points coordinates). I figured out from wikipedia.org and "Digital Modulation Technique" that constellation points will have following coordinates(in the complex plane): 1) (+-sqrt(Eb),0) for BPSK 2) (+-sqrt(2Eb/2),+-sqrt(2Eb/2)) for QPSK 3) (+-sqrt(4Eb/2);+-sqrt(4Eb/2)) and...

Hi all, I have a specific question related to digital communication signals. I am currently looking for a signal model that represents a wide...

Hi all, I have a specific question related to digital communication signals. I am currently looking for a signal model that represents a wide range of digitally modulated communication signals. One of the common signal models that represents the complex envelope of linear modulation schemes e.g. Phase Shift Keying (PSK) and Quadrature Shift Keying (QAM) signals is given by: s(t)= Infinit...

i am working on a software defined radio kit. building a frequency hopping system using QPSK (quadrature phase shift keying) modulation i...

i am working on a software defined radio kit. building a frequency hopping system using QPSK (quadrature phase shift keying) modulation i have got a problem on which i am stuck for weeks now and cant get help anywhere presently i have made system for SINGLE FREQUENCY , i have got two kits (transmitter and receiver) i can transmit and receive simultaneously on a single kit so i first tested...

i have a problem in closed loop control of single phase PWM inverter using (sine modulation)dsPIC30f6010. for open loop control i used sine...

i have a problem in closed loop control of single phase PWM inverter using (sine modulation)dsPIC30f6010. for open loop control i used sine table. how to give reference sine wave for closed loop control of inverter.

It seems that the training symbols have to use the same modulation as the data symbols. Is there any way that I can use different modulations? ...

It seems that the training symbols have to use the same modulation as the data symbols. Is there any way that I can use different modulations? say QPSK for training and 16QAM for data. I tried equalizing the two parts separately with a constellation change in between. The shape of the equalized constellation seems correct, but it is compressed. Of course the demodulation result is wrong. ...