Codan Radio P25 Training Guide - Manual (Page 104)

TRAINING GUIDE | P25 RADIO SYSTEMS
Chapter 7: P25 Phase 2 Page 96
BENEFITS OF P25 PHASE 2
Spectrum Effi ciency
Two-slot TDMA systems double the number of voice paths (compared to FDMA) in 12.5 kHz bandwidth
radio channels and meets the new Federal Communications Commission (FCC) spectral effi ciency
requirements.
Backwards Compatibility
A basic requirement for Phase 2 radio equipment is backward compatibility with Phase 1 radio systems.
Phase 2 two-slot TDMA uses Phase 1 FDMA for the control channel, data capability and all talk-around
/ direct mode communications. Phase 2 uses most of the other interface standards (eg. ISSI, CSSI)
and maintains the IMBE™ / AMBE+2™ vocoder family. Phase 2 maintains all of the Phase 1 encryption
and signaling capability.
Enhanced Functionality
Phase 2 radio systems use bi-directional signaling allowing for emergency alerting and informed
preemption of talkers. Bi-directional signaling is also used for subscriber RF power control for
interference mitigation from fi xed site trunking equipment.
Subscriber Power Savings for Battery Life
Slotted / burst transmission of subscribers improves the battery life of the subscribers. Two-slot TDMA
subscribers transmit approximately 50% of the time compared to FDMA.