Project 25 Documents & Standards Reference
Digital Modulation and Spectrum Efficiency Two-Phase Plan
Project 25 represents the public safety community’s overall strategy to develop a digital modulation solution and achieve FCC spectrum efficiency mandates calling for migration to narrowband channel spacing in the VHF and UHF bands. This migration to narrowband channelization has already been accomplished in the 700 MHz Band, which comprises 108 MHz of spectrum from 698 to 806 designated for commercial and public safety uses.
Narrowbanding is an effort to ensure more efficient use of the VHF and UHF spectrum by requiring all VHF and UHF public safety and commercial LMR systems to migrate to at least 12.5 kHz efficiency technology by January 1, 2013. No date has been established by the FCC for further migration to 6.25 kHz channel bandwidth in any current public safety spectrum.
Project 25 addresses the FCC’s mandate with a two-phase plan.
Phase 1 defines the necessary technologies to provide for channel reduction from 25 kHz to 12.5 kHz. Phase 1 refers to P25 requirements and standards for a digital CAI based on FDMA using a 12.5 kHz channel.
Phase 2 defines an additional 50-percent reduction in channel size to 6.25 kHz or equivalency. Phase 2 refers to P25 requirements and standards for a digital CAI TDMA using a 6.25 kHz equivalent channel, two slots in a 12.5 kHz channel.
