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i am writing a code for ofdm generation, and I have a question regarding the same

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Swapna Iyer
Swapna Iyer on 16 Jun 2011
[EDIT: 20110615 22:33 CDT - reformat - WDR]
after these lines
clear all;close all;echo off;tic;
clc;
para=128;
fftlen = 128 ;
noc = 128;
nd = 6 ;
ml = 2 ;
sr = 250000 ;
br = sr .* ml ;
gilen= 32;
ebn0 = 10;
nloop = 100;
noe = 0;
nod = 0 ;
eop = 0 ;
nop = 0;
Y2 = zeros(para,1);
%h = modem.pskmod (4,0);
seridata = rand ( 1, para*nd*ml)>0.5 ;
paradata = reshape( seridata, para,nd*ml)
x=paradata(1,:)
%in = mat2str(x)
%paradata(1,:)
h = modem.qammod(16);
y2= modulate(h,x)
i get an error
??? Undefined function or method 'ceil' for input arguments of type 'logical'.
_**Error in ==> modem.abstractMod.checkModInput at 13
if isempty(x) || ~isreal(x) || any(any(ceil(x) ~= x)) ...
Error in ==> modem.abstractMod.modulate at 10
checkModInput(h, x);
Error in ==> ofdmbook at 36
y2= modulate(h,x)**
Can someone please tell me what is wrong with my code ??

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Answers (2)

Walter Roberson
Walter Roberson on 16 Jun 2011
Change
seridata = rand ( 1, para*nd*ml)>0.5 ;
to
seridata = 0 + rand ( 1, para*nd*ml)>0.5 ;

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Swapna Iyer
Swapna Iyer on 16 Jun 2011
thanks . I changed it. But I am still getting this error :
??? Undefined function or method 'ceil' for input arguments of type 'logical'.
Error in ==> modem.abstractMod.checkModInput at 13
if isempty(x) || ~isreal(x) || any(any(ceil(x) ~= x)) ...
Error in ==> modem.abstractMod.modulate at 10
checkModInput(h, x);
Error in ==> ofdmbook at 36
y2= modulate(h,x)

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Yella
Yella on 16 Jun 2011
>> h = modem.qammod(16); >> h
h =
Type: 'QAM Modulator'
M: 16
PhaseOffset: 0
Constellation: [1x16 double]
SymbolOrder: 'Binary'
SymbolMapping: [0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15]
InputType: 'Integer'
h isnt a matrix of values its just information of the modem. I think h is a transfer function(channel coefficients). i would suggest u first to modulate the input X = qammod(x,16) and convolute the 'h' with 'X' to get the tranmitter data.

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Swapna Iyer
Swapna Iyer on 16 Jun 2011
qammod(x,16) wont work on my matlab. I think it is obsolete. As you said, h is just used to construct a modulator object and the modulate is used for the modulation process.

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