a question about the carrier recovery od the mobile receiver

[springf2000]

dear all:
i am now stduy the moile communication system.i have a question when i study it, all the reciever structure is as the following:

ANTENNA-----duplex-----bandpass----LNA------DOWNCONVERTER----IF filter--quadrature demodulator------A/D----DSP

now my question is :where and how to realize the carrier recovery or carrier SYNCH
thanks!

 

[Renjith]

The carrier recovery block has to be implented inside the Quadrature demodulator block. The purpose of DigitalDownConverter is to translate ur high freq signal onto the lower band of the spectrum, or say to the base band(which depends on ur NCO frequency).
This down converted signal will be send to Demodulator.
Demodulator will recover the Carrier Signal from this signal. Thus the Demodulator basically consists of a Timing Recovery Block, carrier Recovery block.

 

[springf2000]

Re: a question about the carrier recovery od the mobile rece

thanks for your warm help!
is this carrier recovery way implemented by the DSP or in a digital way!
would y please recommend me some material about it

 

[ddt694]

if the data rate is not too high, you can do carrier recovery inside the DSP. you can search google with these keyword for example: carrier recovery,
digital modem, etc.

 

[Renjith]

Re: a question about the carrier recovery od the mobile rece

is this carrier recovery way implemented by the DSP or in a digital way!

Hi Springf,
sorry,i cud not get a clear picture of ur question.

as per my assumption, i'm writing this....
Carrier recovery algorithm shud b implemented inside the DSP.
it has
multipler blocks--> Phase detector(can b a CORDIC alogorithms)-->Loop Filter-->NCO
Do u have Matlab/Simulink/SystemGenerator tools?

 

[cat_basilio]

Re: a question about the carrier recovery od the mobile rece

Carrier recovery is deccribeg in the book

Algorithms for Communications Systems and Their Applications.
Nevio Benvenuto and Giovanni Cherubini
Copyright 2002 John Wiley & Sons, Ltd. ISBN: 0-470-84389-6

 

[spweda]

Re: a question about the carrier recovery od the mobile rece

Depends on your RF system. For TDMA, PLL is usually used. For CDMA, DLL and AFC are used. Search for google you will find enough information.

 

[Wacko2000]

Re: a question about the carrier recovery od the mobile rece

Some addition to this thread:

Carrier synchronisation should also be considered in conjunction with symbol timing recovery. Some algorithms work fine when symbol timing has been locked and therefore symbol timing recovery has been done in front of carrier synchronization. In these cases CORDIC can be used.
These kind of signal processing blocks are performed in FPGA rather then DSP due to processing power (depends on actual symbol rate speeds and carrier frequencies).

Regards