Hi I'm trying to synchronize on the bits in an asynchronous digital signal using M&M clock recovery block. For instance, roughly 7 samples of +1. represent a "1" and roughly 7 samples of -1. represent a "0".
I've reduced the problem the following test case: a square (or sine) wave generator with a period of 14 samples (a continuous series of 7 sample "1"s and "0"s) and a clock recovery block with the initial value of omega = 7. This is a fair reproduction of what I see on sync headers in my signal, which are a long series of such 101010s https://www.tablix.org/~avian/gnuradio/clock_recovery_test2.grc.png Am I wrong to assume that the clock recovery should in this case return roughly [+1, -1, +1, -1, ...] (synchronizing on the crests of the input signal)? This does not seem to happen, neither for a square wave nor a sine wave. The clock recovery never seems to settle on the correct frequency and phase, even when the initial omega matches input frequency perfectly. I've tried plenty of different settings for mu and omega gains. The sync just drifts more or less slowly. https://www.tablix.org/~avian/gnuradio/clock_recovery_test2.grc_scope.png I see M&M clock recovery is a pretty common source of questions, but I failed to find a good answer on how to use it. A suggestion I saw is to write your own synchronizer. I can do that but I don't want to reinvent the wheel if a well researched one already exists. Am I misunderstanding what M&M clock recovery is supposed to do? Is there another existing block that is more suited for this kind of bit synchronization? Thanks Tomaž _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
