Comtech EF Data SDM-9000 - Manual (Page 213)

SDM-9000 Satellite Modem Options
Rev. 4 A–27
A.2.9.2 Signal Space Mapping
DBS/DVB operation employs conventional Gray-coded QPSK modulation with absolute
mapping (no differential coding). Bit mapping in the signal space is shown in
Figure A-21.
Q
I
I = 0
Q = 0
I = 0
Q = 1
I = 1
Q = 1
I = 1
Q = 0
Figure A-21. QPSK Constellation