User Guide

Technical Documentation
NHD–4
System Overview
PAMS
Page 3–21
Original 11/97
90
Hybrid
o
Σ
CARRIER
INPUT
SIN
COS
I DATA
Q DATA
Values of Data Channels
are –1 and 1, not 0 and 1
CDMA04.DRW
For the reverse link
the Q data is delayed
by 1/2 clock chip. This
modulation is called
OQPSK (Offset Quadra
Phase Shift Keying)
Figure 20. I/Q Modulator
In Figure 20 the 90 phase shifter is used to generate the sine and cosine channel
reference frequency. The two signal paths are called the “In phase” and the
“Quadrature phase” paths, therefore the name, I/Q modulator.