On Thu, 06 Nov 2008 07:53:08 -0600, isnithin wrote:

> Hi,
>    I am building QPSK demodulator on FPGA. I am basically performing
> demodulation with the help of Costas loop.
> 
> My QPSK Digital Demodulator should have following features:
> 
> 1)It should adhere with DVB-S, DVB-S2 Standard. 2)It should perform
> carrier phase recovery and clock recovery.
> 
> 
> I have the following querries:
> 
> 1)Costas loop need Sine/Cosine table for multiplication with the
> incoming modulated samples. On what factors does this table depend on?
> 
> 2)How can I decide on Samples/Symbol. According to my understanding
> samples/symbol=(Bit-rate)/(Sampling frequency of the ADC)
> Note: ADC is the one which converts (receives) analog modulated data and
> converts it into digital.
> Is my understanding correct??
> 
> 3)What will be the Carrier Frequency for DVB-S2 System?
> 
> 4)For the carrier phase recovery using Costas loop, after calculating
> the phase difference, How can I apply this "phase error" for next
> iteration? Should I update the Sine/Cosien tables? how can I control it?
> 
> 5) how can I decide on the parameters for Low pass filter and Loop
> Filter used in the Costas Loop.
> 
> Regards,
> Nithin

Homework?



-- 

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Hi,
   I am building QPSK demodulator on FPGA. I am basically performing
demodulation with the help of Costas loop. 

My QPSK Digital Demodulator should have following features:

1)It should adhere with DVB-S, DVB-S2 Standard.
2)It should perform carrier phase recovery and clock recovery.


I have the following querries:

1)Costas loop need Sine/Cosine table for multiplication with the incoming
modulated samples. On what factors does this table depend on? 

2)How can I decide on Samples/Symbol.
According to my understanding samples/symbol=(Bit-rate)/(Sampling
frequency of the ADC)
Note: ADC is the one which converts (receives) analog modulated data and
converts it into digital. 
Is my understanding correct??

3)What will be the Carrier Frequency for DVB-S2 System?

4)For the carrier phase recovery using Costas loop, after calculating the
phase difference, How can I apply this "phase error" for next iteration?
Should I update the Sine/Cosien tables? how can I control it?

5) how can I decide on the parameters for Low pass filter and Loop Filter
used in the Costas Loop.

Regards,
Nithin