commqpsktxrx tutorial - any comm experts here....?

hi everyone i have been studying digital communication for past 40 days now. i am trying to understand the basic transceiver already implemented in matlab by the name of commqpsktxrx. if anybody is familiar with that (i am sure a lot of people will be) and have studied each of the blocks in detail then please do reply to this post. i have read chapter 5 7 and 8 of michael rice's digital comm because the above discussed receiver is adopted from that. i have understood most of the things. for the past 10 days i have been stuck on the timing recovery block. now in the timing recovery block there are delay elements used between the NCO (interpolation control) and the TED & Interpolation filter. i cant figure out why.? secondly as i see it the interpolation filter is causal that is it operates on previous 3 and current samples. according to the book the interpolated sample corresponds to in between the n-1 and n-2 sample. but here they are using it ass the nth sample. i got doubts on this too. kindly explain i am sure this will be of help to anyone who wants to study this in future since the documentation does not describe in detail the function of each block.

fire away please. regards khurram

[khurram]

anyone......?

[Hamzeh Issa]

Hi, I'm having the same problem... did you find an answer?