A question about digital upconversion, but at the core its about quadrature modulation. I have real I and Q data streams at an IF of 20 MHz, what...

A question about digital upconversion, but at the core its about quadrature modulation. I have real I and Q data streams at an IF of 20 MHz, what do I need to do to "combine" these messages into a single signal at 20 MHz?

Hi, Although, this stuff is considered 'elementary' knowledge for an electrical engineer I still have tonnes of confusion. Can someone take time...

Hi, Although, this stuff is considered 'elementary' knowledge for an electrical engineer I still have tonnes of confusion. Can someone take time to explain this to me? I understand quadrature sampling (books by simon haykin & Richard Lyons do a great job) but I fail to see the practical aspect of this. At the receiver, X(t)cos(wt) --> inphase component X(t)sin(wt) --> quadrature compone

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 new to much of this, so thanks in advance for your patience. Where can you find C++ (or C or C#) source code for ASK, FSK, PSK,...

Hi all, I am new to much of this, so thanks in advance for your patience. Where can you find C++ (or C or C#) source code for ASK, FSK, PSK, QAM, PPM, and BPSK demodulation schemes? I have a feeling that if they exist they won't be free, but that's a problem for another day...Matlab and LabView have great modulation/demodulation toolkits, but we are looking for source code. Thanks again--Ni...

Hi all, I need to do FM on a signal and the FM profile should be triangular. ie. the frequency vs. time plot of the modulated signal should...

Hi all, I need to do FM on a signal and the FM profile should be triangular. ie. the frequency vs. time plot of the modulated signal should have a triangular profile. How can I do this? All help will be greatly appreciated. Thnx in advance. Regards Apurva

Hi, I know this a very newbie question; but it seems to me that all RAKE receiver implementation are for CDMA systems. Can it be used...

Hi, I know this a very newbie question; but it seems to me that all RAKE receiver implementation are for CDMA systems. Can it be used for normal modulation schemes e.g. Coherent (BPSK etc) or non coherent (FSK). Thanks.

Hi, For a M-ary QAM modulation, which has L (L is 2's power) amplitude levels {-L, -(L-1), ... -3, -1, 1, 3, ... L-3, L-1}. The average...

Hi, For a M-ary QAM modulation, which has L (L is 2's power) amplitude levels {-L, -(L-1), ... -3, -1, 1, 3, ... L-3, L-1}. The average energy of equally distributed constellation symbols is: L/2 Eav=2[(2*E0/L) sum{(2*i-1)^2} = (2/3)*(L^2 - 1)* E0 i=1 My question is how to get the last result from the "sum" operation. My text book gives t...

Hello friends, I would like to know if it would be correct if we classify the 3pi/8 offset 8-psk modulation scheme used for EDGE as a type of...

Hello friends, I would like to know if it would be correct if we classify the 3pi/8 offset 8-psk modulation scheme used for EDGE as a type of linear CPFSK? I am quoting this statement based on the understanding that GMSK used for GSM is a non-linear CPFSK. Regards, Pankaj

Hi, There is a formula that gives you the amount of data that can be transmitted on a sub-carrier when the SNR is known and the target BER...

Hi, There is a formula that gives you the amount of data that can be transmitted on a sub-carrier when the SNR is known and the target BER is also known. It is something like this c(n)=log(1+(-1.5/ln(BER))*SNR) However in real applications packets are used and target PER's. I have found a relationship between PER and BER and it goes something like this: PER=1-(1-BER)^L L:length of...

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. ...

Hi, I was wondering if it matters to apply a filter ( root raised cosine, for pulse shaping ) on IQ streams and THEN modulating ( i (t)...

Hi, I was wondering if it matters to apply a filter ( root raised cosine, for pulse shaping ) on IQ streams and THEN modulating ( i (t) * cos(wt) + q (t) * sin (wt) ) or to first modulate and THEN applying the pulse shaping filter on the modulated signal ? thanks in advance, mel

Hi all, Im working on an (synthetic) acoustic experiment: I have a receiver that records waves emitted by two sources S1 and S2. So the...

Hi all, Im working on an (synthetic) acoustic experiment: I have a receiver that records waves emitted by two sources S1 and S2. So the receiver records R=S1+S2. I would like to "filter" R to get only S1 or S2. Is there any way of doing that ?? S1 and S2 are defined in the same frequency band. So i cannot use a simple filter. Im thinking about modulating/demodulation the signals ...

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

Hello, I am honing my skills on the Physical layer of communication systems. I request the knowledgeable members of this group to help me with...

Hello, I am honing my skills on the Physical layer of communication systems. I request the knowledgeable members of this group to help me with the following topics. I'd appreciate that, and I believe this may help other people who would want similar knowledge. 1) On what criterion do we select the original data bits (like it is 244 bits for UMTS 12.2 Kbps) 2) What would be the optimal le...

hey guys, I am currently dealing with sinusoidal signals ranging between 200k and 30MHz and have to measure a phase difference of a few...

hey guys, I am currently dealing with sinusoidal signals ranging between 200k and 30MHz and have to measure a phase difference of a few millidegrees between the two signals. I have read up on a few stratergies like using a PLL or IQ demodulation, but since we are working with such high frequencies it is best to obtain advice from experts here. thanks very much. Best wishes Zoul

I don't have any experience with DSP and my math is very out of shape, so I'm trying to squeeze a lot of info in a very short period. I've been...

I don't have any experience with DSP and my math is very out of shape, so I'm trying to squeeze a lot of info in a very short period. I've been reading on modulation (Amplitude and Frequency) and I'm trying to use an AM to encode binary data, without a carrier wave (or is it a carrier wave of 0?). I think I'm getting the picture wrong, what I'm trying to do is play sound (discrete samples) at 22...

From Wikipedia [[Amplitude Modulation]]: "In modern radio systems, modulated signals are generated via digital signal processing...

From Wikipedia [[Amplitude Modulation]]: "In modern radio systems, modulated signals are generated via digital signal processing (DSP)." While this sounds right, how much DSP is really done in radio transmitters? Are they now using DSP modulators in place of mixers for AM and FM broadcasting? Even more, is there a reference for it? -- glen

Hello.. I want to do some QPSK facility to simple microcontroller. It's seems to work in real life. I do the (not simplified) Goertzl algorithm...

Hello.. I want to do some QPSK facility to simple microcontroller. It's seems to work in real life. I do the (not simplified) Goertzl algorithm and in the end I just use lookup table to calculate arctan. So for now I got phase signal in range pi/-pi (in my case -128 to 127 8 bit output) and as I intend to use difference modulation I got just fine result if I do BPSK. (ie just subtract last p...

For a given modulation constellation (say 16 QAM), is there a minimum EVM (irrespective of how good the SNR is)? This may sound a it silly, but...

For a given modulation constellation (say 16 QAM), is there a minimum EVM (irrespective of how good the SNR is)? This may sound a it silly, but I find that while simulating a 16 qam transceiver system on simple AWGN channel (with no other impairments like phase noise, dc offset, iq mismatch etc) , the evm value more or less flattens (close to 0.0027) when Es/No is beyond 45 dB (below this evm...

A couple of days ago I found my old Micro Professor MPF-1 in my bookshelf and I thought it would be fun coding some on that old thing. I didn't...

A couple of days ago I found my old Micro Professor MPF-1 in my bookshelf and I thought it would be fun coding some on that old thing. I didn't want to code it entering the hexadecimal codes by hand so I thought I use an Z80 assembler on my PC and then transfer the assembled code to the MPF-1 somehow. That somehow I decided to be using the cassette interface :D Then I only had to write some...