Phase 2 implementation achieves the goal of improved spectrum utilization. An alternative 2 slot TDMA solution is currently under development.
P25 Phase 2 uses FDMA - frequency division multiple access and the modulation format is CQPSK. P25 Phase 2 : Phase 2 P25 radio systems are based around a 6.25 kHz channel bandwidth> within this they achieve one voice channel or a minimum 4800 bps data channel. In addition to this, the P25 standards provide an open interface to the RF Sub-System to facilitate interlinking of different vendors' systems. Phase 1 P25 compliant systems are backward compatible and interoperable with legacy FM systems. The Phase 1 radios use a form of modulation known as Continuous 4 level FM, C4FM. P25 Phase 1: The phase 1 Project 25 radios can operate in 12.5 kHz analogue, digital, or a mixed mode format. The TDMA support scanners also do FDMA Phase I Variations GRE PSR-800 (with firmware upgrade, not out of the box).The following scanners can only decode P25 Phase I, but not Phase II: There are conventional voice solutions as well as trunking solutions available for this digital voice solution.Ĭurrently, there are two trunking solutions available that use the P25 IMBE vocoder: Numerous vendors have produced Project-25 capable subscriber equipment, including Motorola, M/A COM, EF Johnson, Uniden, Racal, and others. IMBE stands for Improved Multi-Band Excitation, and was developed by DVSI Inc. It follows the open APCO Project 25 standard. P25 is a standard developed for public safety trunked radio systems. P25 is a radio system using digital voice via the APCO-25 Common Air Interface (P25 CAI) standard. Police and public service is migrating to P25 digital mode, making it impossible to listen on traditional analog police scanners. P25 P-25 APCO 25 APCO-25 APCO Project 25 Astro-25
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