Baseband Frequency offset estimation in matlab

frequency offset estimation matlab

Hi,

Currently, I am doing Baseband frequency offset estimation in matlab. However I had encounted a major problem. At low SNR, my algorithm could not estimate the offset. Anyone can tell me which steps I had missed out in my code? Hope the experts out there can help. This is my matlab code:

Ain=sign(randn(1,1024)); %generate +/- 1
Aupsample=upsample(Ain,4);
rrcfilter=rcosine(1,4,'fir/sqrt',0.3,4); %A rrc filter generate by matlab
Arrc=conv(Ain,rrcfilter); % filter the signal
foff=0.005; %normalise frequency offset
t=1:length(Arrc);
Aoffset=Arrc.*exp(j*foff*t); %frequency offset the signal
Anoisy=awgn(Aoffset,0,'measured'); %add noise
Brrc=conv(Anoisy,rrcfilter); %matched filter the received signal
Bdownsample=downsample(Arrc,4); %downsample the signal
Bframe=Bdownsample(9:end-8 ); %locate start of frame
Bm=Bframe.*conj(Ain); %remove modulation
Bconj=Bm(2:end).*Bm(1:end-1); %frequency offset algorithm
foffest=sum(angle(Bconj)); %estimate frequency offset

This is my simple matlab code. Hope you all can help and tell me why I can't get the frequency offset which I set it at 0.005? When the SNR is high ie: 20 or 30dB, I can frequency offset easily.

Really need your help urgently. Thank you.

carrier frequency offset matlab

your code is not working ,i am a new user and trying to work and seek guidance as well. simply copy ,paste and run ur code u will fine error something like

Error in ==> weboffset_try at 13
Bm=Bframe.*conj(Ain) %remove modulation

matlab frequency offset

Sorry, my line 10 got error. Original is
Bdownsample=downsample(Arrc,4); %downsample the signal
however it should be
Bdownsample=downsample(Brrc,4); %downsample the signal
It should work after you change.

What topic u r researching? care to share?

frequency offset matlab

well babyeric,

i am doing an assignment on the dvb-t synchronisation technique but i dnt knw that how to do it,thats why i said so that i am learning , so depressed that the topic is still not clear to me ,my teacher told me to use these matlab codes for the ofdm transmission and reception and then pass this channel to awgn or shift the signal and then on receiver side implement any synchronisation technique,will u be kind enough in helping me out.the code for the transmission of of without awgn is below and with awgn is the second one link .
1- www.ece.gatech.edu/research/labs/.../tutorials/OFDM/Tutorial_web.pdf

2- faraday.ee.emu.edu.tr/eaince/gradthesis/OFDM_OVER_AWGN.pdf

Like I can see estimate frequency not correctly:
fd - sample frequency
Bconj=Bm(2:end).*conj(Bm(1:end-1)); %frequency offset algorithm
foffest=fd*mean(angle(Bconj))/(2*pi) %estimate frequency offset

foffest=fd*mean(angle(Bconj))/(2*pi)


what will be the fd value in this above equation?????

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