(Update 2018 Feb. 14)
I received an advice from Blockstream engineer. I thank his comment. He doubts that Blockstream signal processing by gnuradio needs much more CPU power than that of Raspberry Pi. They are working to reduce CPU power to handle Blockstream signal on gnuradio. Anyway, I still can't catch QPSK satellite beam in my home region. Next, I will prepare much more powerful PC and try it again to classify my problems under CPU power and the others.
