## Forums Search for: QAM

## Advantages of Gray Coding for QAM

inI 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

inHello 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

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?

inAre 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

inHi, 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

inHi, 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

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

inI 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

inDSP 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

inHi 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

inHi, 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

inGuys, 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

inHi, 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

inI 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

inHello 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

inHello, 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?

inMy 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

inPlease 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

inHello 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

inHi 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