Hi, I am trying to convert stereo into mono in the following manner: R/2 + L/2 This works at most of the times, however, on some case the...

Hi, I am trying to convert stereo into mono in the following manner: R/2 + L/2 This works at most of the times, however, on some case the phase of the right channel is about 180deg of the left channel, using the above formula with phase shift of 180deg results a mute output, the easiest way to resolve that is to use R/2 - L/2 and not R/2 + L/2, this however, is not enough as the phase is ...

How do I modulate a given clock signal, without using any other frequency source(ie. no PLLs, VCOs, Ring osc. etc.) I have only 1 frequency ie...

How do I modulate a given clock signal, without using any other frequency source(ie. no PLLs, VCOs, Ring osc. etc.) I have only 1 frequency ie of the clock signal and I need to modulate that same signal. Is this possible ? Any help would be appreciated. Thnx in advance.... Regards Apurva

Sirs, Many times on this forum, we have discussed about how time domain and frequency domain are mainly just representations In case of...

Sirs, Many times on this forum, we have discussed about how time domain and frequency domain are mainly just representations In case of frequency modulation, why is it necessary to convert this into time domain before transmitting, if they are just representations. Thanks, Manish

When calcualate BER for certain modulation scheme, under Rayleigh fading, exact theoretical valuse is available from books and...

When calcualate BER for certain modulation scheme, under Rayleigh fading, exact theoretical valuse is available from books and publications. But how to do set Rayleigh parameters in the simulation? For example, received signal is r(t) = Alpha * exp(-j*Phi) * s(t) + z(t) ( By Proakis 's book) And s(t) transmitted signal z(t) Gaussian noise ~ N ( 0, Sigma) ...

OFDM is touted as a multipath-resistant modulation, but I have a simple scenario that seems to challenge that assertion. Consider the...

OFDM is touted as a multipath-resistant modulation, but I have a simple scenario that seems to challenge that assertion. Consider the situation in which the received signal consists of the direct path plus a reflected path that is exactly 180 degrees out of phase at the center frequency and at (or near) the same signal strength as the direct path. This is going to cause a deep null. Howe...

I am trying to build a binary CPFSK demodulator with self synchronization. Modulation index is not fixed. I kind of prefer coherent demodulation,...

I am trying to build a binary CPFSK demodulator with self synchronization. Modulation index is not fixed. I kind of prefer coherent demodulation, but not sure how to do the synchronization. The following is some understandings I have during the literature survey, I appreciate if I can get some comment on my understandings. 1. One type of coherent demodulation I know of is ZCD based and using...

I am trying to build a binary CPFSK demodulator with self synchronization. Modulation index is not fixed. I kind of prefer coherent demodulation,...

I am trying to build a binary CPFSK demodulator with self synchronization. Modulation index is not fixed. I kind of prefer coherent demodulation, but not sure how to do the synchronization. The following is some understandings I have during the literature survey, I appreciate if I can get some comment on my understandings. 1. One type of coherent demodulation I know of is ZCD based and using...

Hello, I need to learn and have some basics at hand. I am trying to write code for classifying raw signal data into Marks and spaces and...

Hello, I need to learn and have some basics at hand. I am trying to write code for classifying raw signal data into Marks and spaces and the like. I am also trying to extract encoding info from raw data bits and many more things. I am stumped...at this point. What i am lacking here is basic signal knowledge. Can you please suggest some basic book for understangin signals, modulation, mar...

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'm trying to simulate a spread spectrum signal (a spread version of a pure tone). But I'm not quite clear on how to apply the code to the...

I'm trying to simulate a spread spectrum signal (a spread version of a pure tone). But I'm not quite clear on how to apply the code to the signal. My data is 16-bit integer but the code produces a bit at a time. So do I take 1 6 PN bits and XOR it with each element of the signal? Confused.

Hi all, I am new to demodulation and FEC. How can I get each bit's soft-probability from the constellation? For example, the modulation...

Hi all, I am new to demodulation and FEC. How can I get each bit's soft-probability from the constellation? For example, the modulation method is 16QAM, How can I get P(bit1=0),P(bit2=0),P(bit3=0),P(bit4=0) from a symbol? Is it belong to the subject of detection and need viterbi algorithm? Or can you recommend some key words of this subject? Best regards, Davy

Hello. I'm a newbie of DSP and I have just wrote the software in C for creating a FSK modulation (phase coherent, using a soft DDS) and...

Hello. I'm a newbie of DSP and I have just wrote the software in C for creating a FSK modulation (phase coherent, using a soft DDS) and demodulate it. Actually, I'm using the V.23 modem standard as a start point, so I have generated a 1300/2100Hz FSK with a bit rate of 1200BPS and sampling rate of 8KHz, wrote it to a file and fed to the demodulator. The demodulator is composed by two digital...

Hi, I am trying to understand the difference(s) between OFDM and GFDM which are used as a multicarrier modulation techniques in wireless...

Hi, I am trying to understand the difference(s) between OFDM and GFDM which are used as a multicarrier modulation techniques in wireless communication. As far as I know the OFDM uses the orthogonal subcarriers and the GFDM is with the non-orthogonal subcarriers when designing a transmitter. Could anyone please explain further about their design and differences? What is the purpose of using...

Hi all, I am trying to simulate a data flow according to the wimax standard. Could someone please help to understand how to manage the...

Hi all, I am trying to simulate a data flow according to the wimax standard. Could someone please help to understand how to manage the data flow dimensions after encoding before mapping to ofdm symbols? More precisely: I generate, for example, a message of 72 words having in mind a 16 QAM modulation, with an overall coding rate 3/4. This, after rs and cc coding, interleaving and puncturi...

Hi, Fading channel models (and noise) are usually specified for a modulated waveform. For e.g. Jakes model can be used to generate taps and...

Hi, Fading channel models (and noise) are usually specified for a modulated waveform. For e.g. Jakes model can be used to generate taps and fade the modulated waveform. I would like to know if there is a way in which the channel can be modeled whose I/P is a binary stream of data for e.g. O/P stream of a convolution encoder. The end objective is to by-pass the modulation - dem

Hi , I am trying to model a system ( in MATLAB ) where i have a OFDM system .so i start with generating a random set of data , convert the...

Hi , I am trying to model a system ( in MATLAB ) where i have a OFDM system .so i start with generating a random set of data , convert the data to a parallel form, then a QPSK modulation ,perform a IFFT and then insert a guard interval . now what i intend to do is pass it through a underwater channel model and check for the error rate vs SNR . so in parallel i have a channel matrix as a result...

Can anyone help me in the way of datatapping/sniffing a dial-up modem connection by only access to the complex signals carries in the...

Can anyone help me in the way of datatapping/sniffing a dial-up modem connection by only access to the complex signals carries in the 2-wire link(listening to the voice)? For this purpose it should be to separate the incoming and outgoing signals in full-duplex mode, then demodulating them according to the standard of connection. The most public standard is V.34 uses QAM modulation. Now: -Is it ...

Hi, I get a problem on explaining the performance of GMSK modulator and Gaussian filter, does anyone have idea what is the difference...

Hi, I get a problem on explaining the performance of GMSK modulator and Gaussian filter, does anyone have idea what is the difference between Gaussian filter bandwidth and GMSK modulation? Thank you very much ! Best regards Kan

Hello All I have designed a bandpass signal at carrier frequency of 12KHz and with bandwidth of 8KHz. This signal is convolutionaly encoded...

Hello All I have designed a bandpass signal at carrier frequency of 12KHz and with bandwidth of 8KHz. This signal is convolutionaly encoded with rate 1/2 encoder and QPSK modulation. I do not know how to add noise to this signal. i.e. y=x+sigma*randn(size(x)); where x is my bandpass signal, which is real. I do not know how to find this scaling factor sigma and what should be my noise? ...

I have been experimenting with a Butterworth filter. I must be making a mistake. Here is my problem. The impulse response of the first order...

I have been experimenting with a Butterworth filter. I must be making a mistake. Here is my problem. The impulse response of the first order Butterworth filter is a decaying one-sided exponential. Suppose that the filter is 1/(1 + j f/fc ). Then, the impulse response is 2 pi fc exp(-(2 pi fc) t) u(t). Here pi = 3.14159... u(t) is the unit step. fc is the cutoff frequency. The inpu...