Hi all, I am working on the coexistence study between BT and WLAN. Anyone knows where are the spec on modulation and pulse shaping for BT and...

Hi all, I am working on the coexistence study between BT and WLAN. Anyone knows where are the spec on modulation and pulse shaping for BT and 802.11 a, b, g WLAN? cfy30

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

Hi, QPSK has - 4 constellation points; 16 QAM -16 constellation points; 64 - 64 constellation points. 16QAM vs QPSK -> Now with the 16...

Hi, QPSK has - 4 constellation points; 16 QAM -16 constellation points; 64 - 64 constellation points. 16QAM vs QPSK -> Now with the 16 possible points in the constellation diagram we have 16 possible symbols. For this 16 symbols we need 4 bits for coding . Compared to the QPSK modulation now we have doubled the transfer rate when using the same symbol clock.But compared to the QPSK, points

Hi: What waveform[s] of FSK do[es] the EDT [European Deaf Telephone] protocol use? FSK = Frequency Shift Keying Quote from...

Hi: What waveform[s] of FSK do[es] the EDT [European Deaf Telephone] protocol use? FSK = Frequency Shift Keying Quote from http://www.deaflibrary.org/v18/v18.html : "EDT Operational Mode -- The modulation is frequency shift keyed modulation (i.e. carrier is 10 ms before a character is transmitted and removed 1s after the last character) using Recommendation V.21(1) frequencies. Th...

Hi list, I understand the meaning of spatial diversity and frequency diversity. I'm in search of a proper definition for "Modulation...

Hi list, I understand the meaning of spatial diversity and frequency diversity. I'm in search of a proper definition for "Modulation Diversity". I know that such a thing exists (Google told me), but I'm not able to find the definition or at least understand from some of the papers which mention this term. Any directions? Best Regards, Nagaraj

This freescale appnote: http://www.freescale.com/files/dsp/doc/app_note/AN3059.pdf talks about all the different kinds of channel estimation...

This freescale appnote: http://www.freescale.com/files/dsp/doc/app_note/AN3059.pdf talks about all the different kinds of channel estimation schemes for OFDM reception. They discount differential modulation, but how does it compare with the simplest channel estimation techniques: Least Square (LS)? Alan

The frequency spectrum of an FM signal with a sinusoidal modulating signal is a discrete infinite frequency series where the carrier and...

The frequency spectrum of an FM signal with a sinusoidal modulating signal is a discrete infinite frequency series where the carrier and sidebands are given by the Bessel functions, which are themselves a function of the modulation index. But when the FM signal is modulated by TWO sinusoidal signals, is the spectrum represented by TWO infinite frequency series? Or is the spectrum mo...

I have a confusion here. So please help. I have a message signal given as : m(t) = 0.5 cos(wt) + 0.3 sin (2wt) I also have a carrier...

I have a confusion here. So please help. I have a message signal given as : m(t) = 0.5 cos(wt) + 0.3 sin (2wt) I also have a carrier signal whose amplitude is known. and now i want to calculate the modulation index. which is given as amplitude of message signal divided by amplitude of carrier. (Remember that i am doing AM.) The confusion is that: Does the amplitude of message ...

A Bell 202T modem uses FSK modulation (1200HZ, 2200HZ) and send data at up to 1800 bits per second. I need to replace an "analog" version of...

A Bell 202T modem uses FSK modulation (1200HZ, 2200HZ) and send data at up to 1800 bits per second. I need to replace an "analog" version of this with a digital version, sampling the phone line with an A/D and "decoding" the 1's and 0's in firmware (ARM C). My question is how.. The modulation index is too narrow to count zero crossings, so I believe I need a "phase coherent decoder"...

Hi there, I have a question on OFDM. As we know, most OFDM systems nowadays do not use all the available tones (subcarriers) for data...

Hi there, I have a question on OFDM. As we know, most OFDM systems nowadays do not use all the available tones (subcarriers) for data modulation. Let us say we have 64 tones in total and we might end up with 48 data tones, 4 pilot tones, 3 DC tones and 9 null tones, which is kind of an typical setup. My question is regarding the null tones, which are usually placed on the two boundaries...

Dear All, I'm currently simulating a Alamouti MIMO system to find out the BER for the different number of antennas and different modulation...

Dear All, I'm currently simulating a Alamouti MIMO system to find out the BER for the different number of antennas and different modulation schemes over the Rayleigh fading channel with AWGN for the selected SNR range. I've been using the predefined "modem.pskmod" and "modem.qammod" in matlab for my modulation, demodulation and maximum likelihood decoding. All is working well for the PSK m...

Hi, It is clear that OFDM systems may have different SNR values for each subcarrier due to frequency selectivity of the channel. If an OFDM...

Hi, It is clear that OFDM systems may have different SNR values for each subcarrier due to frequency selectivity of the channel. If an OFDM packet consists of n number of FEC blocks and in case of adaptive modulation and coding systems, a single FEC block may have different modulation scheme. However, is it possible for OFDM (e.g.IEEE 802.11a/n) systems that the block error probability of FEC b...

Hi all I'm working on GMSK modem simulation in MATLAB. I'm almost done with the modulation part albeit i'm not sure if the model I used...

Hi all I'm working on GMSK modem simulation in MATLAB. I'm almost done with the modulation part albeit i'm not sure if the model I used is correct adding to my trouble is the ambiguity with the Power Spectral Density of the GMSK modulated signal (also the MSK modulated signal). Here I'm writing the algorithm I followed to do the simulation: bitrate=4000bps BT=0.3 1.calculated ...

Hello Forum, in AM modulation, a carrier (pure monochromatic signal) is multiplied by the message signal m(t). In angle modulation, the phase...

Hello Forum, in AM modulation, a carrier (pure monochromatic signal) is multiplied by the message signal m(t). In angle modulation, the phase or derivative of the phase is modulated according to m(t). In both case we have a real signal. What is the advantage of associating the analytic signal to the real modulated signal? The analytic signal has its imaginary part equal to the Hilbert tra...

Hi, I have a doubt regarding 1 other project. I have to get the modulation transfer function of an image (and the same image defocused)....

Hi, I have a doubt regarding 1 other project. I have to get the modulation transfer function of an image (and the same image defocused). The defocus is either induced by constructing a bessel filter (similar to airy functions, defocus created by unfocused thin lens). Even though I already designed the filter, I am currently using a webcam to get the defocus by altering the focus of the le...

Hello friends, I am little confused that why do we always apply fourier transform for amplitude modulation, frequency modulation why not laplace...

Hello friends, I am little confused that why do we always apply fourier transform for amplitude modulation, frequency modulation why not laplace transform. Second question is that when I studied control system then everywhere Laplace Transform is used. So please tell me why we use LT in controls and why FT in communication.

I have came across a so-called soft symbol mapper in OFDM system, which I understand it is modulation by soft values, but how to do it? for...

I have came across a so-called soft symbol mapper in OFDM system, which I understand it is modulation by soft values, but how to do it? for example, QPSK modulation will make [0 0] [0 1] [1 0] [1 1] to [-0.7071-0.7071i] [-0.7071+0.7071i] [+0.7071-0.7071i] [+0.7071+0.7071i], how about soft symbol mapper?

Hi there, I'm trying to simulate the adjacent channel(ACI) performance of a continuous phase modulation(CPM) scheme so that I can determine if...

Hi there, I'm trying to simulate the adjacent channel(ACI) performance of a continuous phase modulation(CPM) scheme so that I can determine if my modulator/demodulator meets a particular ETSI performance specification. I'm not sure if my simulation should include AWGN as well as the ACI? Ultimately I'm trying to chose a combination of CPM modulation parameters (alphabet size, pulse shape, pu...

Hi, I am doing the synchronization for ISDB-T at the moment. For pure coherent modulation, it is easy to use the embedded SP for fine...

Hi, I am doing the synchronization for ISDB-T at the moment. For pure coherent modulation, it is easy to use the embedded SP for fine timing synchronization since we may use them to estimate the time domain CIR. However, if differential modulation is adopted, there will not be available SP in the frequency domain, in this case, how fine timing sychronization is done? Many thanks eeed

Hi! I would like to calculate the BER of an optical communications system. The only known value is the total collected intensity as a...

Hi! I would like to calculate the BER of an optical communications system. The only known value is the total collected intensity as a function of time (I thus can calculate mean intensity, variance,...). The modulation format doesn't matter. The simplest is the best; so we can take OOK modulation. I think that BER is also function of the SNR. How can I calculated the BER if I take a O...