Codan Radio P25 Training Guide - Manual (Page 97)

P25 RADIO SYSTEMS | TRAINING GUIDE
Chapter 7: P25 Phase 2 Page 89
A P25 Phase 2 trunking system operates as shown in Figure 7-4.
Figure 7-4: P25 Phase 2 Trunking System
The P25 Phase 2 trunking system uses an FDMA Phase 1 Control Channel (with TDMA extensions
/ advanced signaling) for all registration, channel access and other system control. Two-slot TDMA
channels are used for voice traffi c channels, and FDMA channels are used for data traffi c channels.
The Phase 2 subscribers request a voice traffi c channel by communicating with the TRC on the control
channel using advanced signaling (over Phase 1) to identify the TDMA time slots.
A P25 Phase 2 two-slot TDMA fi xed site trunking system and subscribers will support the Phase 1
CAI. This facilitates interoperability among multiple manufacturers’ equipment, migration planning from
Phase 1 FDMA to Phase 2 two-slot TDMA, and inter-system roaming, according to network operator
requirements.
Subscriber Unit Subscriber Unit
Registration
Registers on Phase 1 FDMA
Control Channel
(with TDMA extensions /
advanced signalling)
Talk Group
Control
Channel
FDMA
Phase 1
12.5 KHz
Voice Call
Assigned any Phase 2 TDMA
Traffic Channel (with time slot)
for all Voice Communications
Traffic (Data)
Channel
FDMA
Phase 1
12.5 KHz
Traffic (Voice)
Channel
TDMA
Phase
2
12.5 KHz
TDMA
Phase
2
Traffic (Voice)
Channel
TDMA
Phase
2
12.5 KHz
TDMA
Phase
2
Subscriber Unit Talk Group
Data Transmissions
Assigned any Phase 1 FDMA
Traffic Channel for all
Data Communications
Trunking Resource Controller (TRC)
C4FM
C4FM C4FM
C4FM
C4FM
H-CPM
H-DQPSK
H-DQPSK
H-CPM
C4FM