Hi, In my 16-QAM constellation the symbol 0011 at located at I=1, Q=3. What binary or hex value do I output for 1 and 3 if I am using say 16 bit signed binary? Can I use say 7FFFh for 3 and e.g. 2AAAh for 1? Are standards available to show what values should be used? Many Thanks Bob
16-QAM modulation output values
Started by ●October 26, 2007
Reply by ●October 26, 20072007-10-26
stenasc@yahoo.com writes:> Hi, > > In my 16-QAM constellation the symbol 0011 at located at I=1, Q=3. > What binary or hex value do I output for 1 and 3 if I am using say 16 > bit signed binary? Can I use say 7FFFh for 3 and e.g. 2AAAh for 1?It really depends on where that output is going and how your modulator is implemented. Is the output going to a quadrature upconverter? Do you have a datasheet for that part?> Are standards available to show what values should be used?I don't think so. This is implementation-specific. -- % Randy Yates % "She has an IQ of 1001, she has a jumpsuit %% Fuquay-Varina, NC % on, and she's also a telephone." %%% 919-577-9882 % %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO http://www.digitalsignallabs.com
Reply by ●October 26, 20072007-10-26
On 26 Oct, 14:11, Randy Yates <ya...@ieee.org> wrote:> sten...@yahoo.com writes: > > Hi, > > > In my 16-QAM constellation the symbol 0011 at located at I=1, Q=3. > > What binary or hex value do I output for 1 and 3 if I am using say 16 > > bit signed binary? Can I use say 7FFFh for 3 and e.g. 2AAAh for 1? > > It really depends on where that output is going and how your modulator > is implemented. Is the output going to a quadrature upconverter? Do you > have a datasheet for that part? > > > Are standards available to show what values should be used? > > I don't think so. This is implementation-specific. > -- > % Randy Yates % "She has an IQ of 1001, she has a jumpsuit > %% Fuquay-Varina, NC % on, and she's also a telephone." > %%% 919-577-9882 % > %%%% <ya...@ieee.org> % 'Yours Truly, 2095', *Time*, ELO http://www.digitalsignallabs.comHi Randy, Thanks for replying. I am implementing on an FPGA. I suppose I can apply scaling if required. Bob
Reply by ●October 26, 20072007-10-26
stenasc@yahoo.com writes:> On 26 Oct, 14:11, Randy Yates <ya...@ieee.org> wrote: >> sten...@yahoo.com writes: >> > Hi, >> >> > In my 16-QAM constellation the symbol 0011 at located at I=1, Q=3. >> > What binary or hex value do I output for 1 and 3 if I am using say 16 >> > bit signed binary? Can I use say 7FFFh for 3 and e.g. 2AAAh for 1? >> >> It really depends on where that output is going and how your modulator >> is implemented. Is the output going to a quadrature upconverter? Do you >> have a datasheet for that part? >> >> > Are standards available to show what values should be used? >> >> I don't think so. This is implementation-specific. >> -- >> % Randy Yates % "She has an IQ of 1001, she has a jumpsuit >> %% Fuquay-Varina, NC % on, and she's also a telephone." >> %%% 919-577-9882 % >> %%%% <ya...@ieee.org> % 'Yours Truly, 2095', *Time*, ELO http://www.digitalsignallabs.com > > Hi Randy, > > Thanks for replying. I am implementing on an FPGA.So you're transmitting a 16-QAM signal out of an FPGA? :) -- % Randy Yates % "She's sweet on Wagner-I think she'd die for Beethoven. %% Fuquay-Varina, NC % She love the way Puccini lays down a tune, and %%% 919-577-9882 % Verdi's always creepin' from her room." %%%% <yates@ieee.org> % "Rockaria", *A New World Record*, ELO http://www.digitalsignallabs.com
Reply by ●October 26, 20072007-10-26
Yep, Already done it for DQPSK. Symbol Mapping, Filtering, Waveform generation, Mixing, etc then out to the DAC....then the Analog circuitry took over. Bob
Reply by ●October 26, 20072007-10-26
stenasc@yahoo.com writes:> Yep, > > Already done it for DQPSK. Symbol Mapping, Filtering, Waveform > generation, Mixing, etc then out to the DAC....then the Analog > circuitry took over.My point was this: knowing what levels to output on the DAC is a system design question. You need to know what's after the DAC. For example, maybe the system designers intended the maximum magnitude of the DAC to be 6FFFH (I just pulled this out of the air) so that they could perform some sort of transmitter linearization operation. But, lacking any other information about the rest of the transmit chain, I would think you had it right from the git-go - output the maximum levels you can. -- % Randy Yates % "Remember the good old 1980's, when %% Fuquay-Varina, NC % things were so uncomplicated?" %%% 919-577-9882 % 'Ticket To The Moon' %%%% <yates@ieee.org> % *Time*, Electric Light Orchestra http://www.digitalsignallabs.com
Reply by ●October 28, 20072007-10-28
On 26 Oct, 17:48, Randy Yates <ya...@ieee.org> wrote:> sten...@yahoo.com writes: > > Yep, > > > Already done it for DQPSK. Symbol Mapping, Filtering, Waveform > > generation, Mixing, etc then out to the DAC....then the Analog > > circuitry took over. > > My point was this: knowing what levels to output on the DAC is > a system design question. You need to know what's after the > DAC. For example, maybe the system designers intended the maximum > magnitude of the DAC to be 6FFFH (I just pulled this out of the > air) so that they could perform some sort of transmitter > linearization operation. > > But, lacking any other information about the rest of the transmit chain, > I would think you had it right from the git-go - output the maximum > levels you can.Thanks Randy, Appreciate the help. Bob
