just like 
the picture1, i exe the grc file and got the ber is near zero,i think this is normal
then i seprate this grc into wo part
the one is chunks to symbols+uhd_sink
the other is uhd_source+constellation decoder,
disable the noise,
the result is
it is too large ,this is symbol error rate。
next is my set of uhd
center_freq is 433M
i want to know is there something wrong in my the uhd setting,
and why the symbol error rate is so large.
hope i have Elaborated my problem clearly
--Ekko
