Re: [oc] DPLL

[rahill13@msn.com]

----- Original Message ----- 
From: alexhu@a...  
To: haoguang.guo@p... , cores@o...  
Date: Tue, 5 Feb 2002 08:30:23 +0100 
Subject: Re: [oc] DPLL 

> 
> 
> 
> 
> ----- Original Message ----- 
> From: haoguang.guo@p... 
> To: cores@o... 
> Date: Thu, 15 Nov 2001 09:58:20 +0800 
> Subject: Re: [oc] DPLL 
> 
> > 
> > 
> > Hi, 
> >            I have a problem about  bit synchronization when 
> use 
> > QPSK in satellite communication. When design the demodulator , 
> how 
> > can i get the 
> > bit clock?  Some one said because of the fading and unknown 
> delay , 
> > you can not synchroniza to the transmitter . so must  use the 
> > equalizer to estimate the channel. Is it right? 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > "Sam Gladstone" <samg@t... >@opencores.org on 
> > 11/15/2001 06:29:28 AM 
> > 
> > Please respond to cores@o... 
> > 
> > Sent by:  owner-cores@o... 
> > 
> > 
> > To:     <cores@o... > 
> > cc:      (bcc: Haoguang Guo/SHA/SC/PHILIPS) 
> > Subject:  Re: [oc] DPLL 
> > Classification: 
> > 
> > 
> > 
> > I take it you are demodulating back to a certain softbit size? 
> > There is several books out there that are pretty good. I will 
> find 
> > the 
> > one I used when we were writing an 802.11a phy for a company. 
> > 
> > The main idea is to demodulate each dimension of the 
> > QPSKconstellation data 
> > seperately by 
> > breaking the real and imaginary up into two seperate 
> demodulations. 
> >  Linear 
> > extrapolations can be used to generate softbits for a first 
> order 
> > method. 
> > There are more cost effective, but 
> > harder to understand methods available as well. 
> > (Assuming that you have already done the proper power and 
> phase 
> > corrections.) 
> > I think the number of softbits generated looks like this 
> table. 
> > BPSK - 1 softbit per constellation 
> > QPSK - 2 softbits per constellation 
> > QAM-16 - 4 softbits per constellation 
> > QAM-64 - 6 softbits per constellation 
> > (QAMs get nasty because they are like combinations of 
> different 
> > codings that 
> > have 
> > to have multiple softbits generated per demension because of 
> grey 
> > coding 
> > with the 
> > modulution module. Yuck! ) 
> > 
> > I will try to find the book name and send it out. 
> > 
> > Regards, 
> >   Sam 
> > 
> > ----- Original Message ----- 
> > From: <aolmo@g... > 
> > To: <cores@o... > 
> > Sent: Wednesday, November 14, 2001 9:24 AM 
> > Subject: [oc] DPLL 
> > 
> > 
> > > Hi, 
> > > 
> > > I take the liberty disturbing you. 
> > > I am a friend from Taiwan. 
> > > After reading your posts on Web, I know you are a 
> professional 
> > > communication designer. 
> > > Now I am designing QPSK demodulator for wireless Lan with 
> > verilog. 
> > > Where can I find more helpful material, such as verilog 
> code 
> > for DPLL. 
> > > Please kindly to give me some advice. 
> > > Thank you a lot! 
> > > 
> > > 
> > > 
> > 
> 
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