Hi, An early-late correlator is used by most rake receivers for fine tracking. The way it is done, is to have an early code, an ontime code, and a late code correlated with the incoming stream, where the delays between the early-ontime, and ontime-late codes are equal. Now, it is said that the ontime position is "correct", when the result of the cross correlation with the early code is equal to that of the late code. To me, this does not seem obvious... This would happen only if the cross correlation function was an even function. What guarantees this? Appreciate your help. - Ravi
Early-Late correlator for DLL
Started by ●November 9, 2004
Reply by ●November 9, 20042004-11-09
Duh! Figured this out. It's the autocorrelation that's being performed here... And that's an even function. The only caveat is that the tracking needs to be done over symbols that have the same value. Ravi Srikantiah wrote:> Hi, > > An early-late correlator is used by most rake receivers for fine > tracking. The way it is done, is to have an early code, an ontime code, > and a late code correlated with the incoming stream, where the delays > between the early-ontime, and ontime-late codes are equal. Now, it is > said that the ontime position is "correct", when the result of the cross > correlation with the early code is equal to that of the late code. To > me, this does not seem obvious... This would happen only if the cross > correlation function was an even function. What guarantees this? > > Appreciate your help. > > - Ravi