hi all, I"m working on a simulation of comparing OFDM with different modulation schemes (QPSK,QAM) etc'... My question is about the conversion...

hi all, I"m working on a simulation of comparing OFDM with different modulation schemes (QPSK,QAM) etc'... My question is about the conversion from Es/No to Eb/No I'm not sure if I need to take the cyclic prefix under consideration for instance: Es/No=Eb/No+10log10(log2M * Nc) + 10log10(CodeRate) + ... .. 10log10(Tinf/(Tinf+Tcp)) is the last part correct? where Tinf - is the inf...

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...

Hello everybody! I'm using a Barker sequence to achieve communication synchronization and a first AGC and phase detection. For the moment I...

Hello everybody! I'm using a Barker sequence to achieve communication synchronization and a first AGC and phase detection. For the moment I use a classic 13 symbols long Barker sequence: [+1 +1 +1 +1 +1 ?1 ?1 +1 +1 ?1 +1 ?1 +1] The thing is that I use a QPSK modulation and I was wondering if this was the most efficient way or if there were Barker sequences for complex alphabets.

Hi fellows, since I appreciate very much your opinion and expertise, I'd launch some brainstorming around a future project we plan. This is...

Hi fellows, since I appreciate very much your opinion and expertise, I'd launch some brainstorming around a future project we plan. This is the idea: We have a sine wave signal @ 1MHz which carries analog modulation and - naturally lots of unwanted noise etc. Frequency of the unmodulated signal is known, the phase however isn't (might vary but can be assumed as stable, but unknown). We'...

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...

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 ...

Dear sir / Madam, I am doing M.E in Communication system, i have gone through the concept and fundamentals of OFDM first time , but i could...

Dear sir / Madam, I am doing M.E in Communication system, i have gone through the concept and fundamentals of OFDM first time , but i could not understand the process of IFFT in OFDM modulation, why FFT is not taken at the first stage? if any kind personality explains the concepts behind the IIFT in OFDM, which will helpful for me to understand better. How can i get e-version of any OFDM text...

Dear all It seems I have forgot all my fundamentals. Can you please guide me on how to add noise to the system. So far I did simulations at...

Dear all It seems I have forgot all my fundamentals. Can you please guide me on how to add noise to the system. So far I did simulations at baseband where we just map the data to symbols and add noise. i.e. for 1/2 rate convolution and 4-QAM modulation, SNR=Eb/NO=1/(sigma^2); and from this find the sigma and multiply with random sequence. But how does this differ at passband? Where my ...

Hello , I despair on how to regain the initial information from the seperate I and Q bits after MSK modulation/demodulation. If d(t) is...

Hello , I despair on how to regain the initial information from the seperate I and Q bits after MSK modulation/demodulation. If d(t) is the data, a sum of delta pulses g(t) is the frequency response (MSK: REC) and c(t)=g(t)*d(t) (* convolution !) then phi(t) is the phase , which is calculated by cumsum(c(t)) (MSK:"linear ramps up and down according to the bit") an...

I have a background in traditional digital and RF wireless communications. Normally, when working with link budgets, I can determine the SNR at...

I have a background in traditional digital and RF wireless communications. Normally, when working with link budgets, I can determine the SNR at the receiver, and then calculate the Eb/No given the bit rate. Finally, based on the modulation, I can calculate the BER for the link. I have moved into optical communications, and although the basic theory is the same, the terminology is very di...

Hello all, I am involved in the development of an underwater modem. Right now I am dealing with the simulation stage with simulink. The...

Hello all, I am involved in the development of an underwater modem. Right now I am dealing with the simulation stage with simulink. The modulation scheme I am using is a non-coherent FSK. The carrier frequencies are 20kHz and 22kHz. At the demodulator part, I have designed a matched filters scheme, with both bandpass FIR filters at 20 and 22kHz respectively. The question is, which should ...

Hi All: I am studying RFID DSP, the reader's carrier frequency(Fc) is 13.56Mhz. and the tag use load modulation to modulate the carrier with...

Hi All: I am studying RFID DSP, the reader's carrier frequency(Fc) is 13.56Mhz. and the tag use load modulation to modulate the carrier with sub-carrier, which is Fs = Fc/16. The sub-carrier is OOK modulated with symbol. Could this processe be written as: S(t) = sin(2*pi*Fc*t) * sin(2*pi*Fs*t) * m(t) (m(t) is the symbol pulse) what I don't understand is that the demodulator use a quad...

Hi all, I was wondering how can I calculate data rate given: -B: bandwidth -cr: code rate (say convolution code) -some modulation scheme...

Hi all, I was wondering how can I calculate data rate given: -B: bandwidth -cr: code rate (say convolution code) -some modulation scheme assume the sinr is good enough thanks, Yiu

This should be a familiar problem to many of you. I recorded animal vocalizations at 100kHz, and they have a frequency content from 200Hz to...

This should be a familiar problem to many of you. I recorded animal vocalizations at 100kHz, and they have a frequency content from 200Hz to about 35kHz. Unfortunately (what with old age...) I didn't hear that a TV monitor in the room generated a very strong 16kHz and 32kHz. It's quite stable in frequency but with a strong (regular) amplitude modulation. I am having a heck of a hard time remo...

PAM in digital = AM in analog PFM in digital = FM in analog PCM in digital = x in analog What is "x"? Pulses are digital. Codes are...

PAM in digital = AM in analog PFM in digital = FM in analog PCM in digital = x in analog What is "x"? Pulses are digital. Codes are also digital.

Dear all, I've heard and even read this term in the context of the performance of coding/modulation schemes. But what does it actually mean? ...

Dear all, I've heard and even read this term in the context of the performance of coding/modulation schemes. But what does it actually mean? What's so important about determining the pair-wise probability? What's wrong with the triplet-wise probability or any other combination? I'm trying to gain an intuitive understanding of why this is so desirable, but am failing miserably, can some...

So I want to investigate how to process a pulse signal from contact of human skin i.e. picking up the frequency pulse from the finger. I need...

So I want to investigate how to process a pulse signal from contact of human skin i.e. picking up the frequency pulse from the finger. I need the steps on how this works in detail in general and also consider what level of amplification, modulation and filtering it needs. I am trying to impliment this using a raspberry pi so I can output the signal waves on a screen from the pi. Additional informa...

Hello, For a project which I'm working on, I have a 60Hz sinewave modulated with a square wave at 0.5Hz, modulation is 2.72% The signal...

Hello, For a project which I'm working on, I have a 60Hz sinewave modulated with a square wave at 0.5Hz, modulation is 2.72% The signal comes sampled at 8kHz, I should downsample it to 200Hz, so M = 40. I do that in two stages, first with M1 = 10, then with M2 = 4. I implemented polyphase structure in Simulink, and runs great. By "great" I mean that the output signal, sampled at 200Hz, p...

I am working on baseband portion of a software defined radio on a Blackfin DSP platform. Using I and Q signals in the quadrature modulator , I...

I am working on baseband portion of a software defined radio on a Blackfin DSP platform. Using I and Q signals in the quadrature modulator , I want to try out various modulation schemes like AM, FSK,FM,BPSK,GMSK, QPSK and QAM. I am not very familiar with MATLAB. I would like some help on simulation of the quad modlr block with MATLAB codes, not with the tool boxes. Also some information is needed ...

Hi, I was wondering who discovered/engineered the modulation behind the Milstar constellation (famous for its "waterdrops" signal.) Was it an...

Hi, I was wondering who discovered/engineered the modulation behind the Milstar constellation (famous for its "waterdrops" signal.) Was it an individual or a group of people, and were there any famous people on the payroll? I read something about a famous actress who worked on Frequency Hopping Spread Spectrum, which is what this satellite is believed to use. Undoubtedly there ha

Ben Bradley wrote: ... > That's an "interesting" discussion but doesn't give a clue about > the internals of "digitally controlled...

Ben Bradley wrote: ... > That's an "interesting" discussion but doesn't give a clue about > the internals of "digitally controlled Class D." > > Googling found this paper which has some technical meat - it > mentions regular PWM, digital-input PWM, and "Direct delta-sigma > modulation" that is exactly what I was thinking of:: > http://www.chipidea.com/essderc2003/presentati