Oqpsk Demod

Hi all ,
      I implement qpsk demodulator on National instruments Fpga . Now i
want to Demodulate  Oqpsk signal . As the difference between qpsk and
oqpsk is  only the delay of one bit period in q channel.
 
Q1. Can a qpsk demodulator with some changes  demodulate oqpsk data ?

Q2. If it works , what changes  i should  make ?
           flow of qpsk demodulater what i made..
               1. frequency shifter (input from step 4)
               2. Matched filter
               3. AGC
               4.  coarse frequency offset estimator (Rife and broostyn
algorithm).
               5. Timing recovery (Gardener)
               6. DDPLL
               7. symbol demapping
        
      what are the stages to be modified?

Q3. suggest me some papers ?  


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>Hi all ,
>      I implement qpsk demodulator on National instruments Fpga . Now i
>want to Demodulate  Oqpsk signal . As the difference between qpsk and
>oqpsk is  only the delay of one bit period in q channel.
> 
>Q1. Can a qpsk demodulator with some changes  demodulate oqpsk data ?
>
>Q2. If it works , what changes  i should  make ?
>           flow of qpsk demodulater what i made..
>               1. frequency shifter (input from step 4)
>               2. Matched filter
>               3. AGC
>               4.  coarse frequency offset estimator (Rife and broostyn
>algorithm).
>               5. Timing recovery (Gardener)
>               6. DDPLL
>               7. symbol demapping
>        
>      what are the stages to be modified?
>
>Q3. suggest me some papers ?  
>
>
>---------------------------------------
>Posted through http://www.FPGARelated.com

For QPSK I will recover timing first then do carrier tracking.
Though I haven't done oqpsk but I don't think Gardner TED algorithm for
either qpsk or oqpsk to be any different as it is based on sample rate of
2*symbol rate and oqpsk just means restricted symbol transtions on IQ
quadrants (tx transitions through origin avoided). 

Once you recover timing then delay I relative to Q (opposite tx) and apply
carrier tracking as for qpsk.

Kaz
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