Advantages of Gray Coding for QAM

Started by Deamon in comp.dsp7 years ago 29 replies

I have been reading about QAM modulation and wondering when I gray code what advantage is that for my BER as the SNR increases Is there much...

I have been reading about QAM modulation and wondering when I gray code what advantage is that for my BER as the SNR increases Is there much difference for a 16 QAM system or this effect does not help at all at 16 QAM system. Any reference would be appreciated.


16 QAM vs 16 PSK and 4QAM vs QPSK

Started by Anonymous in comp.dsp10 years ago 8 replies
QAM

Hello All, Just curious why in many standards, to achieve different rates, usually use QPSK and 16-QAM. Why can't we use 4-QAM instead of QPSK...

Hello All, Just curious why in many standards, to achieve different rates, usually use QPSK and 16-QAM. Why can't we use 4-QAM instead of QPSK or 16-QPSK instead of 16 QAM? Thanks. Regards, Terry


VSB as QAM

Started by twitto in comp.dsp10 years ago

Hi, I'm currently try to develop an 8-VSB demodulator (for ATSC terestrial digital TV). I saw that there is a simple way to covert to 8-VSB...

Hi, I'm currently try to develop an 8-VSB demodulator (for ATSC terestrial digital TV). I saw that there is a simple way to covert to 8-VSB signal to 64-QAM (offset QAM, to be more precise). My question is: is demodulating QAM is more cost-efficient than woking directly on VSB signal? (by means of equalization, synchronization etc') Thanks!


QAM Example Programs?

Started by glazarev in comp.dsp10 years ago 14 replies
QAM

Are there any good/simple QAM example programs online that I can look at and learn how to use QAM. Thanks, DspN00b.

Are there any good/simple QAM example programs online that I can look at and learn how to use QAM. Thanks, DspN00b.


question about multistage decoding

Started by shirley in comp.dsp10 years ago 6 replies
QAM

Hi, I am working on a multistage channel decoding module for DRM system. I am confused about the QAM demapping. In case of 64 QAM, I begin with...

Hi, I am working on a multistage channel decoding module for DRM system. I am confused about the QAM demapping. In case of 64 QAM, I begin with LSB ( with has highest protection) and get hard decodion. Then for the CSB, I got a shrinked 16 QAM. Then for MSB, 4 QAM. Now the second iteration begins. Now I should make use of the CSB and MSB information to demapp the LSB. But I am afraid it is not co...


Pilot Symbol Assisted QAM

Started by Anonymous in comp.dsp11 years ago 1 reply

Hi, How the pilot symbol assisted QAM works ? What are the symbol information sent on this Pilot ? It's in the same frequency band than...

Hi, How the pilot symbol assisted QAM works ? What are the symbol information sent on this Pilot ? It's in the same frequency band than the QAM modulation ? I think we send a BPSK pilot over the QAM modulation in time duplex ? Do you have good paper on that, I found nothing over google... Thanks


16-QAM Monte Carlo computer simulation

Started by ahkuan in comp.dsp11 years ago

Hi, i need to do a symbol error rate calculation base on the 16-QAM Monte Carlo simulation and also the 16 QAM theoritical formula.My question...

Hi, i need to do a symbol error rate calculation base on the 16-QAM Monte Carlo simulation and also the 16 QAM theoritical formula.My question is, how to i change the following PSK Monte Carlo simulation code into the QAM Monte Carlo simulation code? since we know the QAM is the PSK + PAM. Thanks for any help. % ---------------------------------------- % +++++ Simulation of PSK De...


BER for QAM

Started by Newee_expert2000 in comp.dsp10 years ago 5 replies

I have a system through which I send a QAM signal. After the system, I get a noisy version of the transmitted signal. I want to describe the...

I have a system through which I send a QAM signal. After the system, I get a noisy version of the transmitted signal. I want to describe the system by its BER (or any conventional definitions related). I would like to use the definition of "Error Vector". I mean "complex transmitted QAM symbol - complex received QAM symbol" Furthermore, the noise added by the system has a white spectrum. T...


Spectral efficiency of MSK and GMSK

Started by aizza ahmed in comp.dsp6 years ago 8 replies

DSP experts, landed into problem, kindly help. at this...

DSP experts, landed into problem, kindly help. at this link, http://cp.literature.agilent.com/litweb/pdf/5965-7160E.pdf i see Modulation Theoretical bandwidth format efficiency limits MSK 1 bit/second/Hz BPSK 1 bit/second/Hz QPSK 2 bits/second/Hz 8PSK 3 bits/second/Hz 16 QAM 4 bits/second/Hz 32 QAM 5 bits/second/Hz 64 QAM 6 bits/second/Hz 256 QAM 8 bits/seco...


Gray code for QAM

Started by Krishna in comp.dsp9 years ago 12 replies
QAM

Hi All, Can you please point me to reference(s) explaining the construction of Binary to Gray code conversion for a general QAM...

Hi All, Can you please point me to reference(s) explaining the construction of Binary to Gray code conversion for a general QAM constellation. I just know that the QAM maybe treated as independent PAM links + some added constraints to ensure that the adjacent constellation points differ by only one bit. Thanks, Krishna ~blogs @ http://www.dsplog.com


64 QAM

Started by Anonymous in comp.dsp14 years ago 1 reply

Hi, Anyone knows where to find Matlab source code to simulate 64 QAM modulation/demodulation. Regards, Ren?

Hi, Anyone knows where to find Matlab source code to simulate 64 QAM modulation/demodulation. Regards, Ren?


Capacity for QAM

Started by hramcha in comp.dsp7 years ago 16 replies
QAM

Guys, I need a clarification on shannon capacity equation for QAM systems with coding. Lets assume M-QAM with code rate R Let m =...

Guys, I need a clarification on shannon capacity equation for QAM systems with coding. Lets assume M-QAM with code rate R Let m = log2(M) My goal is to find at what SNR (Eb/No) we achieve capacity with the shannon equation. C= Wlog2(1+SNR). I am a little confused. can someone please explain with an example value of M and R Thanks H


QAM and Gardner synchronization

Started by Anonymous in comp.dsp10 years ago 4 replies
QAM

Hi, I would like to knwow if the QPSK Gardner algorithm for symbol recovery works too for QAM or MPSK signals ? Thanks

Hi, I would like to knwow if the QPSK Gardner algorithm for symbol recovery works too for QAM or MPSK signals ? Thanks


QAM vs. APSK

Started by affectionate_ty in comp.dsp6 years ago 2 replies
QAM

I need a practical explanation as to why QAM (e.g. 16QAM) performs better than APSK (e.g. 16APSK) in a linear channel (AWGN). Thank you.

I need a practical explanation as to why QAM (e.g. 16QAM) performs better than APSK (e.g. 16APSK) in a linear channel (AWGN). Thank you.


help with algorithm/schematic/Vhdl code for QAM

Started by Tony Acquah in comp.dsp12 years ago 1 reply
QAM

Hello Everyone, I am working on designing a digital modulator that will implement QAM on FPGA. The FPGA will be programmed in VHDL to...

Hello Everyone, I am working on designing a digital modulator that will implement QAM on FPGA. The FPGA will be programmed in VHDL to modulate an input signal(maybefrom a function generator) A D/A converter will convert the digital signal to an analog one that canbe transmitted. Anyway, what I need now is algorithm and/or VHDL code that will carry out the QAM on FPGA. Any help is...


QAM Flat Rayleigh Fading

Started by mylilbaby2003 in comp.dsp10 years ago 21 replies

Hello, I am trying to simulate QAM Flat Rayleigh Fading, but I keep getting 50% for BER with increasing SNR. I use qammod to encode the bits...

Hello, I am trying to simulate QAM Flat Rayleigh Fading, but I keep getting 50% for BER with increasing SNR. I use qammod to encode the bits to QAM and deqammod to decode. I have the transmitted vector go through the Rayleigh channel by this: ry=h.*ty where ry is the received vector, h is the Rayleigh channel, and ty is the transmitted vector. To find the bit energy, I have thi...


How do I evaluate the power spectra density of QAM signals?

Started by Franc in comp.dsp11 years ago 1 reply

My system comprises of a QAM mapping and up-sampling filter, now I need to evaluate the PSD of the I/Q data after up-sampling. How do I do that...

My system comprises of a QAM mapping and up-sampling filter, now I need to evaluate the PSD of the I/Q data after up-sampling. How do I do that in Matlab? TIA.


QPSK or QAM on cable system

Started by nonahvy in comp.dsp9 years ago 1 reply

Please tell me which is a reliable modulation to use in CATV system, QPSK or QAM? What are the advantages and disadvantages. Please discuss it in...

Please tell me which is a reliable modulation to use in CATV system, QPSK or QAM? What are the advantages and disadvantages. Please discuss it in a "lay man's term" and set some examples. Thank you and more power.


16-QPSK Vs 64 QAM

Started by syedmeeran in comp.dsp7 years ago 1 reply

Hello All, As an additional question . I am just confused in terms of detecting errors , Can anyone please tell which modulation scheme ...

Hello All, As an additional question . I am just confused in terms of detecting errors , Can anyone please tell which modulation scheme 16-QPSK or 64 QAM would be easy to detect errors and where does the basic criteria lies. Thanks in Advance Syed


16-QAM

Started by jimmy1 in comp.dsp7 years ago 4 replies
QAM

Hi everyone, I have a question, A maximum transmission vector in 16-QAM constellation is 100 volts rms. I have to determine the long-term...

Hi everyone, I have a question, A maximum transmission vector in 16-QAM constellation is 100 volts rms. I have to determine the long-term average power transmitted from a 50 ohm antenna if each point in the constellation is equally likely to be transmitted. Any ideas? Thank you Jimmy