[Discuss-gnuradio] timestamp counter-extra ticks in 1st frame

[Pham, Thanh]

I am using the two lines in the rx_nop_handler.h to print out the
timestamp. 
         printf("W0: %08x  TS: %08x\n", metadata->word0,
metadata->timestamp);
       printf("I0: %08x\n", items[0]);


Looking at the timestamp that was printed out from usrp2_fft.py, I
notice that there is always a few extra ticks in the first frame.
I'm trying to understand why. Does someone have an explanation? Thanks!



TS (hex)        TS(decimal)     # of ticks in frame
(decim_rate=16)
507c5e55        1350327893      
507c7594        1350333844      5951    (1st frame has 15 extra ticks,
this number changes with decimation rate but not consistent)
507c8cc4        1350339780      5936
507ca3f4        1350345716      5936
507cbb24        1350351652      5936
507cd254        1350357588      5936
507ce984        1350363524      5936
507d00b4        1350369460      5936
507d17e4        1350375396      5936
507d2f14        1350381332      5936
507d4644        1350387268      5936
507d5d74        1350393204      5936
507d74a4        1350399140      5936
507d8bd4        1350405076      5936
507da304        1350411012      5936
507dba34        1350416948      5936
507dd164        1350422884      5936
507de894        1350428820      5936
507dffc4        1350434756      5936
507e16f4        1350440692      5936
507e2e24        1350446628      5936