ButchGone
Member
So, I was surfing around trying to get some more information about the EADS P-25 trunking system going in Cumberland County, TN. I started doing more searches on EADS, which appears to be a major communications player giving Motorola a run for their money with this pilot system in the US.
Anyway, I ran into a lot of info about the next generation of digital two-way comms, called P-25 Phase 2 and is under development. While it will be some years before Phase 2 is the standard and everybody is now buying Phase 1 systems, it appears that unless scanners will be capable of monitoring TDMA 6.25khz wide transmissions we will not be able to hear anything down the road. TDMA is just one of several ways to push voices through the air, that was used in earlier cell phone systems. Just food for thought since analog FM and now even Phase 1 P-25 12.5khz wide digital seem to have a limited "freshness date."
Also, isn't TDMA used in the newer MA/COM systems? Isn't there a push to get everyone to transmit with a narrower 6.25khz bandwidth by a certain date? What will future scanners do, or will licensing keep us from being able to hear systems like the current MA/COM stuff?
BG..
PS...this is the latest from the P-25 folks:
Project 25 Steering Committee
Position Release
May 2, 2007
Project 25 Phase 2 Decisions and Direction
For many months, the Project 25 Steering Committee has been encouraging and assisting in the work of the Telecommunications Industry Association (TIA) and its standards-formulating body, TR8, to reach consensus on the technology to be used in the next generation of Project 25 systems. In order to achieve advanced levels of capacity and functionality, the technology centered on Time Division Multiple Access techniques and has been referred to as Project 25 Phase 2.
This search for the next generation of the Project 25 digital system has been underway for several years in a very deliberative process. Many thousands of hours of engineering effort have gone into this process by some of the best communication equipment companies and minds in the world during the TIA and Project 25 process. The issues and the needs of public safety have demanded the most thorough examination and decision-making process.
The Steering Committed received multiple quality proposals from TIA member companies, and all of these proposals received high levels of examination by TIA members and public safety users. All proposals have gone through an exhaustive process within the TIA standards process so as to fully understand the advantages of each proposal. After several years of regular face-to-face meetings and dozens of international teleconferences, there were two primary proposals. Each proposal came with its own significant attributes.
At the TIA Project 25 meetings the week of April 23 in Dallas, Texas, the Steering Committee made two significant decisions relative to the Phase 2 technology. First, the Steering Committee accepted the consensus of the TIA members in selecting a new Vocoder for all Phase 2 applications. The Steering Committee chose the DVSI Enhanced Dual Rate (Enhanced Half Rate/Enhanced Full Rate) IMBE Vocoder. This Vocoder advances the capabilities of Project 25 systems, improves on Phase 1 performance and audio quality, and is fully compatible with the Vocoder of Phase 1.
The second decision was to select the best proposal attributes from the harmonization process. In the end, the majority of the Project 25 Steering Committee selected the 12-kilobit per second, two-slot TDMA solution. This selection not only will allow for graceful migration and compatibility with Phase 1 systems, but it also advances capabilities into an even more robust Project 25 system. This solution was chosen in order to accommodate ever-increasing needs for efficiency and capacity in public safety wireless voice and data radio systems while ensuring full-feature functionality and improved audio quality. The Steering Committee’s primary decision elements considered the needs of public safety over all other considerations.
Anyway, I ran into a lot of info about the next generation of digital two-way comms, called P-25 Phase 2 and is under development. While it will be some years before Phase 2 is the standard and everybody is now buying Phase 1 systems, it appears that unless scanners will be capable of monitoring TDMA 6.25khz wide transmissions we will not be able to hear anything down the road. TDMA is just one of several ways to push voices through the air, that was used in earlier cell phone systems. Just food for thought since analog FM and now even Phase 1 P-25 12.5khz wide digital seem to have a limited "freshness date."
Also, isn't TDMA used in the newer MA/COM systems? Isn't there a push to get everyone to transmit with a narrower 6.25khz bandwidth by a certain date? What will future scanners do, or will licensing keep us from being able to hear systems like the current MA/COM stuff?
BG..
PS...this is the latest from the P-25 folks:
Project 25 Steering Committee
Position Release
May 2, 2007
Project 25 Phase 2 Decisions and Direction
For many months, the Project 25 Steering Committee has been encouraging and assisting in the work of the Telecommunications Industry Association (TIA) and its standards-formulating body, TR8, to reach consensus on the technology to be used in the next generation of Project 25 systems. In order to achieve advanced levels of capacity and functionality, the technology centered on Time Division Multiple Access techniques and has been referred to as Project 25 Phase 2.
This search for the next generation of the Project 25 digital system has been underway for several years in a very deliberative process. Many thousands of hours of engineering effort have gone into this process by some of the best communication equipment companies and minds in the world during the TIA and Project 25 process. The issues and the needs of public safety have demanded the most thorough examination and decision-making process.
The Steering Committed received multiple quality proposals from TIA member companies, and all of these proposals received high levels of examination by TIA members and public safety users. All proposals have gone through an exhaustive process within the TIA standards process so as to fully understand the advantages of each proposal. After several years of regular face-to-face meetings and dozens of international teleconferences, there were two primary proposals. Each proposal came with its own significant attributes.
At the TIA Project 25 meetings the week of April 23 in Dallas, Texas, the Steering Committee made two significant decisions relative to the Phase 2 technology. First, the Steering Committee accepted the consensus of the TIA members in selecting a new Vocoder for all Phase 2 applications. The Steering Committee chose the DVSI Enhanced Dual Rate (Enhanced Half Rate/Enhanced Full Rate) IMBE Vocoder. This Vocoder advances the capabilities of Project 25 systems, improves on Phase 1 performance and audio quality, and is fully compatible with the Vocoder of Phase 1.
The second decision was to select the best proposal attributes from the harmonization process. In the end, the majority of the Project 25 Steering Committee selected the 12-kilobit per second, two-slot TDMA solution. This selection not only will allow for graceful migration and compatibility with Phase 1 systems, but it also advances capabilities into an even more robust Project 25 system. This solution was chosen in order to accommodate ever-increasing needs for efficiency and capacity in public safety wireless voice and data radio systems while ensuring full-feature functionality and improved audio quality. The Steering Committee’s primary decision elements considered the needs of public safety over all other considerations.
