OVERVIEW: Digital Modulation Technology
2
Figure 1. Spectrum of IDEN Quad 16QAM
Time Division Multiple Access (TDMA)
is used to allocate portions of the RF sig-
nal by dividing time into six slots, one for each unit. Time allocation enables each
unit to transmit its voice information without interference from another unit’s
transmission.
Transmission from a unit or base station is accommodated in time-slot lengths of
15 milliseconds and frame lengths of 90 milliseconds (see Figure 2 on page 3).
0
-10
-20
10
20
Frequency from Desired Channel Center
(kHz)
RL 0dBm 10 dB/
Power
(dB)
-10
-20
-30
-40
-50
-60
-70
