On Thu, Jun 02, 2005 at 09:21:59AM -0700, Sachi wrote: > Hi, all > I am still studying the codes of the FSK_R(T)X.py. > It's a little bit confusing because the comments are > rather limited. > Which algorithm or book chapter does the author refer > to when he wrote the codes, especially for the time > synchronization part? I think that information can > help me understand the code line by line much better. > > Thanks in advance > > Sachi
Hi Sachi, The time synchronization method is a standard open loop technique that works fine for many uses. It results in establishing both bit timing and frame alignment. Fundamentally we start with a signal that is oversampled 8 times, and then look for a particular synchronization pattern at every possible offset. When we find the best one, we declare that we are synchronized, and use that alignment for the duration of the current frame. It's similar to the oversampling techinque used in UARTs to find the middle of the start bit. Synchronization is generally not well covered in intro comms texts. Frerking, "Digital Signal Processing in Communication Systems" is full of practical digital comms techniques, including some having to do with synchronization. Meyr, Moeneclaey and Fechtel, "Digital Communications Receivers: Synchronization, Channel Estimation, and Signal Processing" is pretty much all about synchronization, but is pretty heavy going. Eric _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
