800 MHz Radio System Public Safety Radio System Migration

 System Use

 History of system

 System Configuration

 Proposed migration plan Public Safety Radio System 2013 Activity

 19,405,644 transmissions in 2013 • Sheriff’s Office 8,266,598 = 47% • Fire* and EMS 4,471,845 = 25% • County Government 2,943,209 = 17% • City of Naples 1,551,858 = 9% • City of Marco 432,088 = 2% * 5 independent, 2 County, and 2 municipal fire departments  38 Agencies and government departments  System supports 4200 mobile and portable radios

Public Safety Radio System History & Cost

 1994 - System RFP & contract $8.3 mil  1995 - 1996 Construction & loading  1999 - City of Naples added to $100k system  2002 - Simulcast expansion rural $1.375 mil fringe  2007 - Simulcast technology Upgrade $4.5 mil  2008 - ESC including CCSO 9-1-1 $2.9 mil  Included site technology upgrades

800 MHz System Configuration

 12 Sites utilizing 41 channels  Redundant site at the ESC  System Command and Control at County Barn Site and the ESC  All Sites are linked with a digital microwave network  2 911 centers with 16 consoles - CCSO and NPD

Public Safety Radio System Technology

• Channels are shared among all users = efficient use of available frequency spectrum • Users are divided into talk groups not assigned to specific channels • System assigns groups to available channels • System establishes communication privacy • Improves cross agency communications • Provides group/user priority for access during busy times What is Trunking ? Computerized Channel Assignment Conventional Approach Trunked Approach

Bank Tellers SALES COUNTER SALES COUNTER Being Served

System channels are shared not dedicated to a user Obstacles to Signal Propagation

3 watt

35 watt Public Safety Radio System Technology

 Current system has been use for 18 years, approaching end of life in 2017  Technology protocols are changing  What's Next? – P25 Phase 2 • P25 is a suite of standards for digital radio systems • Released in 1995 and the standards continue to evolve • P 25 standards offer improved interoperability between systems and different vendors equipment • P25 Phase 2 standards improve system performance and capabilities  Strong federal support of P25 technology through grants and federal purchasing requirements Public Safety Radio System Technology Migration

 Gradual migration – immediate improvement for public safety and maximizing existing investment  FY 14 upgrades • Two equipment shelters • Replacement of three battery back up systems • Replacement of three site generators • Radio system command and control hardware that will integrate current and future technology  FY 14 efforts will include an interim solution to improve portable radio coverage in North Naples that will transition to a P25 site in FY 15 Public Safety Radio System Technology Migration

 FY 15 site component replacement and migration of public safety users  FY 16 to FY 18 complete installation of site components and migration of system users  Anticipated five year cost is $15 million  The system vendor is offering pricing concessions for existing customers keeping us on budget  The State of Florida Contract pricing remains in effect until 2021

Future Considerations

• System users have identified the following topics as areas for future action:

• Establish standards for in building coverage by ordinance or inclusion in the LDC • Identify areas where additional system resources will be needed due to growth • Utilization of impact fees for funding radio system expansion and improvements

800 MHz Maintenance

 Radio repair services are available 24 hours a day for any system issue  System infrastructure is regularly checked according to established maintenance schedules  Mobile and portable radios require annual maintenance checks  Radio software is periodically updated to resolve issues/improve performance

Public Safety Radio System

Questions ???

John Daly Telecommunications Manager 239-252-2531 [email protected]

Backup Materials Background:

The FCC’s release of 800 MHz frequencies in the 1970s provided for the development of public safety communications systems with significantly improved capabilities over existing systems of that era. The Law Enforcement Assistance Administration initiated a project to develop the capabilities and standards needed in a trunked radio system. This project was a joint effort with Association of Public Safety Communications Officials (APCO) and became known as APCO Project 16. The Project 16 standards released in 1979 included:

 Channel access time  Unit and group addressing  Unit and group priority  Data systems interface  Individuality of system users  Command and control flexibility  System growth capability  Frequency use  Reliability

APCO Project 16 addressed operational and functional requirements not technical requirements. As a result manufacturers developed proprietary systems to meet the standards.

Collier County’s EDACS system is compliant with Project 16 standards. The system was implemented in 1995 with users transitioning to the system in 1996. With periodic upgrades to expand system coverage, improve technology, and replace obsolete components, the system will serve Collier for at least twenty years. The user base has expanded from 1600 radios in 1996 to 4,200 today generating 1.7 million radio transmissions monthly.

In 1989 in response to Congressional and FCC direction; APCO formed a working group known as APCO (P25) to establish standards for digital two way radio communications for public safety. Unlike Project 16, Project 25 was tasked with developing technical requirements not just performance standards with the primary goals of improving interoperability among public safety agencies and efficient use of radio frequency spectrum. The Project 25 committee includes; local, state, and federal public safety representatives, representatives from Federal technical agencies and telecommunications industry representatives. The standards released in the 1995 continue to evolve and Project 25 is an ANSI (American National Standards Institute) standard. The attached white paper from LR Kimball written for a county in Pennsylvania provides detailed background on P25. Project 25 Phase 2 standards improve performance in several areas including more efficient use of frequency spectrum and a migration to a Project 25 Phase 2 system is the recommended migration path for Collier County.

What do we do next?

As a result of a variety of actions including federal procurement requirements for communication equipment, federal grant guidance, regulatory actions and technology innovations, the Project 25 standard has emerged as the as the choice for public safety radio system technology. SAFECOM, which is an emergency communications program in the Department of Homeland Security (DHS), provides communications grant guidance for federal agencies awarding grants and grant applicants. SAFECOM guidance specifically states that “grantees should target funding toward standards–based equipment that enables the entity to support implementation of Project 25 equipment for mission critical voice”. This link will take you to the SAFECOM grant guidance document: http://216.81.81.251/SiteCollectionDocuments/2013_SAFECOM_Guidance_Feb_22_FINAL.PDF

Several agencies in Collier have been successful applying for federal communication equipment grants and purchased multi-mode portable and mobile radios compatible with the County’s current technology and P25 to prepare for system migration and interoperability with P25 systems as they are implemented. Agencies purchasing new or replacement radios are also purchasing multi-mode radios to achieve the same goal. There is an expectation that future grant guidance from SAFECOM may require that the radio system the radios operate on be P25 compliant also. Without a migration plan in place the agencies in using the Collier system may be denied grants if the SAFECOM guidance is changed.

P25 radio systems are replacing legacy radio systems not just as a response to the P25 standard but also due to technology evolution. Just as we see in data networks and telephone systems the technology protocols that drive these systems are changing to provide additional capabilities and reliability. In radio we see the same situation and with the development of the P25 standard manufactures are dedicating research and design resources to the standards process.

With commercial systems and the developing national broad band network unable to support mission critical public safety voice communications for the immediate future, it is necessary to plan for and fund upgrades for the public safety radio system. The backbone of the next system must be able to fully support and operate the legacy voice radio system Collier currently utilizes until it is no longer needed, a P25 phase 2 voice radio system as users are migrate to it, LTE data, and interface with other external legacy or standards based systems as needed using the core P25 capabilities. The interface between the current legacy system and P25 must support all current features of the legacy system; unit ID, radio priority, emergency, patching of groups; and seamless integration of the talk groups resident on each system.

With funding in place the considerations that will be evaluated are as we plan implementation are:

 How soon will Collier Public Safety responders need P25 capability to improve interoperability? Numerous counties in Florida including Miami-Dade, Volusia County, Hillsborough, and Lee have all begun P25 migration while maintaining the legacy system. Mobile County Alabama is proceeding with a migration plan very similar to what is being proposed for Collier. Mobile is transitioning public safety users to P25 and keeping government users on the legacy system for several more years.

 The estimated replacement value for all radios operating on the Collier System exceeds $12,000,000. A phased migration allows users to replace radios not compatible with P25 over several years and continue use of the legacy system.

 A phased migration will allow project scope to be evaluated prior to initiating each phase to meet any changes in technology or operational requirements.

 Once P25 technology is available to system users, there will be additional vendor choices available for mobile and portable radio purchases. This is where the savings in a standards based system will be realized. It is important to understand that the open aspect of a P25 primarily applies to the over the air segment of the system, talking to the radios in the user’s hands. Command and control protocols and network switching between sites are not as tightly specified at this time.

 With changing operational requirements for public safety responders it is important to have a plan in place. With rapidly changing events a secure, interoperable digital network will become critical especially for law enforcement.

 Collier County must provide reliable communications for public safety responders. Aging system components need to be upgraded before there is degradation in service or a critical equipment failure.

Conclusion:

Clearly a combination forces have resulted in the emergence of the P25 digital standard as the platform for future radio systems. Collier County’s desired path for radio system migration provides the improved communication capabilities and resources vital for public safety responders while maximizing the investment in the current system. A onetime replacement of the current system would have a significantly higher cost. In addition, the next generation radio system switch offers the ability to integrate multiple technologies and other products into the system. This will allow an evaluation of required capabilities and available technologies prior to implementing each phase of the project which may afford some cost savings. Many of the core components in the current system have been in use since day one nearly twenty years and a P25 system will be no different. This is a long term investment with a strong technology foundation.

Submitted by: John Daly, Telecommunications Manager Information Technology Department

FY 14 800 MHz Radio System Capital Improvement Plan

Dispatch Consle Replacement 1,303,666.80 17 dispatch consoles Engineering, Installation, Project Management Training and cutover assistance

VIDA High Availability Network 2,215,258.28 Switching Center 24 port EDACS gateway 48 Port Interoperability Gareway Logging Recorder interface Logging Recorder upgrade P25 Licenses Engineering, Installation, Project Management

Replacement of UPS Units 75,000.00 North Naples WAVV Marco Island

Replacement of Generators 120,000.00 North Naples WAVV Corkscrew

Replacement of Equipment Shelters 225,000.00 North Naples Immokalee

FY 14 Total 3,938,925.08

1/15/2014 RADIO SYSTEM FIVE YEAR UPGRADE PLAN

Components FY 14 FY 15 FY 16 FY 17 FY 18 Totals Dispatch Consoles 1,304,000.00 - - - - 1,304,000.00 Network Switch 2,220,000.00 - - - - 2,220,000.00 UPS Units 75,000.00 - - - 75,000.00 150,000.00 Generators 120,000.00 - - - 120,000.00 240,000.00 Equipment shelters 225,000.00 - - - - 225,000.00 P25 Site Upgrades Simulcast - 3,900,000.00 500,000.00 - - 4,400,000.00 P25 Site Upgrades Multisites - - 2,500,000.00 1,500,000.00 - 4,000,000.00 Microwave/Site Connectivity - - 1,400,000.00 - 750,000.00 2,150,000.00 3,944,000.00 3,900,000.00 4,400,000.00 1,500,000.00 945,000.00 14,689,000.00

1/16/2014

National Public Safety Telecommunications Council

Why Can’t Public Safety Just Use Cell Phones and Smart Phones for Their Mission Critical Voice Communications?

It's not that simple. Commercial Cellular Voice is Different

* * * * * * * *

Why Can’t Public Safety Just Use the Planned Nationwide Public Safety Broadband Network for Their Mission Critical Voice Communications?

Again, it’s not that simple.

NPSTC Information for Local, Tribal, State, and Federal Officials, April 15, 2013

National Public Safety Telecommunications Council INFORMATION FOR LOCAL, TRIBAL, STATE, AND FEDERAL OFFICIALS Why can’t public safety just use cell phones and smart phones for their mission critical voice communications? Unfortunately it’s not that simple. Although public safety regularly use cell phones, smart phones, and other commercial devices and services as a secondary form of communications, these devices and systems are currently not sufficiently suited for public safety mission critical voice communications during critical incidents. Public safety officials cannot depend upon commercial systems that can be overloaded and unavailable. Experience has shown such systems are often the most unreliable during critical incidents when public demand overwhelms the systems. Public safety officials have unique and demanding communications requirements. Optimal public safety radio communications require:  Dedicated channels and priority access that is available at all times to handle unexpected emergencies.  Mission-critical one-to-many group capability, a feature not available in today’s commercial cellular systems.  Highly reliable, secure, and redundant networks under local control that are engineered and maintained to withstand natural disasters and other emergencies.  The best possible coverage within a jurisdictional area, with a minimum of dead zones – even in areas where commercial cellular services are not economically viable.  And, unique, ruggedized equipment designed for quick response in emergency situations. First responders must not be forced to dial, wait for call connections, or get busy signals when seconds mean the difference between life and death! Why can’t public safety just use the planned nationwide public safety broadband network (NPSBN) for their mission critical voice communications? Again, it’s not that simple. Although the nationwide public safety broadband network (NPSBN) will have voice capabilities that will be valuable to public safety, the network will not be able to initially provide (for many years and maybe never) the mission critical level of voice service and dependability needed by public safety. The NPSBN is intended to provide urgently needed broadband data capabilities for public safety and is not initially being designed to replace current land (LMR) mission critical public safety voice systems. One key element lacking for the NPSBN to replace LMR is that the NPSBN will use LTE commercial technology, a network technology that does not currently provide the “OFF NETWORK” capability that is critical to public safety. This means that when the broadband network is not available or not reachable there will be no communications, a critical requirement for public safety. Other key elements required for mission critical voice include but are not limited to:  Nationwide broadband build out: It will take 10 years or more to build out the nationwide public safety broadband network to provide mission critical coverage equal to current public safety land mobile networks.  Direct Mode or Talk Around: The capability to communicate unit-to-unit when out of range of a wireless network OR when working in a confined area where direct unit-to-unit communications is required.  Push-to-Talk (PTT): The standard form of public safety voice communications today. The speaker pushes a button on the radio and immediately transmits the voice message to one or many other units. When they are done talking they release the PTT switch and return to the listen mode of operation.  Group Call: This method of voice communications provides communications from one-to-many members of a group and is of vital importance to the public safety community. There is much debate relative to whether broadband will eventually have the capabilities to replace current mission-critical public safety LMR systems, however the facts are clear that if this capability becomes reality it is not likely to happen in less than 10 years. Local, tribal, state, and federal public officials are urged to not abandon or stop funding their public safety voice LMR systems until such time as it can be demonstrated that broadband can safely and adequately provide public safety with the mission critical requirements currently provided by LMR.

NPSTC Information for Local, Tribal, State, and Federal Officials, April 15, 2013

The National Public Safety Telecommunications Council (NPTSC) is a federation of organizations whose mission is to improve public safety communications and interoperability through collaborative leadership. Voting Members 1. AASHTO ...... American Association of State Highway and Transportation Officials 2. ARRL ...... American Radio Relay League 3. AFWA ...... Association of Fish and Wildlife Agencies 4. APCO ...... Association of Public-Safety Communications Officials – International 5. FCCA ...... Forestry Conservation Communications Association 6. IACP ...... International Association of Chiefs of Police 7. IAEM ...... International Association of Emergency Managers 8. IAFC ...... International Association of Fire Chiefs 9. IMSA ...... International Municipal Signal Association 10. NASCIO ...... National Association of State Chief Information Officers 11. NASEMSO ...... National Association of State Emergency Medical Services Officials 12. NASF ...... National Association of State Foresters 13. NASTD ...... National Association of State Technology Directors 14. NENA ...... National Emergency Number Association 15. NSA ...... National Sheriffs' Association Associate Members (Non-Voting) 1. ATIS ...... Alliance for Telecommunications Industry Solutions 2. CITIG ...... Canadian Interoperability Technology Interest Group 3. NCSWIC...... National Council of Statewide Interoperability Coordinators 4. TIA ...... Telecommunications Industry Association 5. UTC ...... Utilities Telecom Council Liaison Organizations (Non-Voting) 1. FCC ...... Federal Communications Commission 2. FEMA ...... Federal Emergency Management Agency 3. FPIC ...... Federal Partnership for Interoperable Communications 4. NTIA ...... National Telecommunications and Information Association 5. OEC ...... Office of Emergency Communications 6. OIC ...... Office for Interoperability and Compatibility 7. PSCE ...... Public Safety Communication Europe 8. US DOI ...... US Department of the Interior 9. US DOJ ...... US Department of Justice

Resources: NPSTC Mission Critical Voice Definition http://www.pscr.gov/projects/broadband/reqs_stds/Functional_Description_MCV_v5.pdf Voice over Broadband Articles: Voice and Public Safety Broadband http://andrewseybold.com/3038-voice-over-public-safety-broadband Mission-Critical Voice over LTE: What, When and How? http://andrewseybold.com/2772-mission-critical-voice-over-lte-what-when-and-how Mission-Critical Voice and LTE: Be Careful http://andrewseybold.com/2772-mission-critical-voice-over-lte-what-when-and-how –

NPSTC Information for Local, Tribal, State, and Federal Officials, April 15, 2013

White Paper for Project 25: Background, History, Objective and Phases

prepared for Adams County, Pennsylvania

February 2010

www.kimballcorp.com

Project 25: Background, History, Objectives and Phases

History of P25

Before the advent of digital radio technologies, most frequency modulated (FM) land mobile radio (LMR) systems had the ability to communicate with each other, whether from vendor A or vendor B, as long as the correct frequencies were used, and any “control tones” were used by all. As the digital era of communications emerged, this became more difficult with the advent of differing technologies from multiple vendors. It became apparent that a digital radio from vendor A might not, and in most cases could not due to differing protocols, talk to a digital radio from vendor B.

In October of 1989, The Association of Public-Safety Communications Officials (APCO) assigned and created Project 25, the next sequential number assigned for that year within APCO. This project was assigned the task of researching the differing technologies in digital communications.

Project 25 truly came to fruition in a meeting jointly sponsored by APCO, the National Association of Telecommunications Directors (NASTD), the National Telecommunications and Information Administration (NTIA), the National Communications System (NCS), and the U.S. Department of Defense (DoD).

All agencies present decided that a standard was needed, not only to evaluate basic digital technologies, but to develop a set way to use specific ones emerging in FM land mobile radio systems markets. These standards were viewed as a way to ensure that radios purchased, especially by public safety entities, whether from vendor A or B, could once again talk to one another.

Objectives of P25

¾ Provide enhanced functionality with equipment and capabilities focused on public safety needs ¾ Improve spectrum efficiency ¾ Ensure competition among multiple vendors through open systems’ architecture ¾ Allow effective, efficient, and reliable intra-agency and inter-agency communications

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Since then, P25 has transformed into an industry-wide effort to set the recommended voluntary standards of uniform digital FM two-way radio technology for public safety organizations, as well as a common platform that could be used throughout the U.S.

APCO’s objective was to find solutions that would best serve the needs of public safety. In addition, the P25 Committee encouraged and welcomed the participation of numerous international public safety organizations and equipment suppliers, hoping to make this a truly worldwide recommended standard-setting initiative.

Standards of P25

In January of 1993, APCO Project 25 moved forward by adopting a proposed open system architecture through six interface standards that would determine the future of digital technology, for use in the United States public safety markets. These interface standards would allow vendors to compete in the market, as long as the standards were met.

Since then, data interface has been rewritten to include two separate interfaces— subscriber data Interface and data networks Interface. Also, fixed station interface was added, since the fixed base station must interface the voice as well as data of the subscriber units and mobile data terminal.

¾ Common Air Interface (Um) ¾ Peripheral (Subscriber) Data Interfaces (A) ¾ Data Host or Networks Interface (Ed) ¾ Fixed Station Interface (Ef) ¾ Telephone Interconnect Interface (Et) ¾ Inter-RF Subsystem Interface (G) ¾ Network Management Interface (En) ¾ Console Subsystem Interface (Ec)

All interfaces are bound together in what is commonly referred to as the radio frequency subsystem (RFSS). The RFSS can be technically made up of any RF site equipment, as long as that equipment supports the common air interface, and has the process to interface with the open architecture of all other interfaces.

Common Air Interface (CAI)

The objective of the CAI is to ensure that P25-compliant subscriber equipment from one vendor will be interoperable with subscriber equipment from another.

www.lrkimball.com

This means that all vendors must use the same type of equipment configurations for coding and decoding the digital signal, and must produce the same digital results.

P25 technology uses an improved multi-band excitation (IMBE) vocoder to convert the voice signal to a digital bit stream. This vocoder has an additional advantage in that it is designed to only digitize the voice signals, and ignores unwanted outside noises.

On the transmit side, the CAI of a radio uses a specific voice encoder/decoder (vocoder) device and process to convert the analog voice signals from the subscriber/user into a digital bit stream. This digital bit stream, or digitized voice, is then applied to the RF section of the radio for transmission.

Subsequently, on the receive side of the radio, the RF section receives the RF signal, converts it back to a digital bit stream, and forwards it to the vocoder. The vocoder uses this bit stream to create a synthetic version of the original voice signal.

Subscriber Data Interfaces (A)

The purpose of the peripheral (subscriber) data interface is to allow bursts of digital data (data packets) to be transferred between computers, such as a , whether they are interconnected through a portable or mobile radio, to a fixed- facility computer or . It also allows for the use of a mobile data terminal (MDT) in lieu of another subscriber unit computer.

The mobile data interface standard provides the ability of passing data packets by using transmission control protocol/Internet protocol (TCP/IP) standards version 4 and 6 (IPv4, IPv6). These protocols are used for the following:

¾ Between MDTs ¾ Between mobile or portable subscriber units and a MDT ¾ From a MDT to a to a fixed host ¾ From a subscriber unit to a fixed host

Data Network (Host) Interface (Ed)

The fixed data network interface standard provides for the ability of a “fixed” network computer or server to pass the same data to an MDT, subscriber unit, or

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any fixed computer in the network. It has the ability to transfer that data by TCP/IP, X.25, or system network architecture (SNA).

Fixed Station Interface (FS)

The FS is used to provide communications between a fixed station and the RFSS, or to the console subsystem. This could be in the form of data, or messaging, to support analog as well as digital voice. The FS has two main schemes,

conventional (CFSI) and digital (DFSI). The CFSI can provide for interfacing a conventional analog or digital signal to the RFSS or CS; however, the DFSI can ONLY be used to interface digital voice or data to the RFSS and CS.

Telephone Interconnect Interface

The telephone interconnect interface allows an interconnection between the RF subsystem of a private P25 system, and a public switched telephone network (PSTN). This would provide the ability of “dialing in” to a P25 system through a local telephone switchboard.

Inter-RF Subsystem Interface (ISSI)

The inter-RF subsystem interface (G Interface) standard was written to allow any P25 subscriber unit RF subsystem to connect to and communicate with the RF subsystem of any other P25 subscriber unit, or fixed base, regardless of the settings of the CAI, or the manufacturer. It also currently has the ability in Phase 1 to interface to analog signals.

The requirements of any vendors Inter-RF Subsystem will be the following:

¾ It shall support the following modes of operation o Conventional o Trunked o Mixed mode ¾ It shall support the following network configurations in any of the three modes of operation o Point-to-point o Multipoint ¾ It shall support bearer media Interconnection o T1, E1, and fractionals o Aggregation of these into higher bandwidths, such as SONET

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Network Management Interface (NMI)

The NMI is the brains and single point control behind a P25 system. It maintains the database listings of all equipment, settings, and functionality of the system. The NMI uses these database listings and settings to control how the subsystems, as well as subscriber units, function during operation. Is also includes all fixed encryption equipment in order to control the operation of any secure link. These listings fall under one of the five following categories:

1. Configuration Management—stores and allows access for changes to the system 2. Fault Management—tracks faults within the whole system 3. Security Management—controls security issues, such as encryption, as well as updating encryption of subscriber units on a recurring basis. This includes the key management facility (KMF). 4. Performance Management—tracks performance of all subsystems 5. Accounting Management—accounts for all equipment, including tracking of subscriber unit locations, if applicable.

Console Subsystem Interface (CSSI)

The CSSI is a multiple channel digital interface. It allows for the simultaneous connection to multiple subscriber units through the RFSS, as well as connection to multiple fixed stations.

The CSSI is an Ethernet 100 BaseT interconnection. It is used to interface users/subscribers and fixed station traffic with the dispatcher.

Phases of P25

APCO P25 was written to provide for a timely migration to an advanced, digital, narrowband radio system. This narrowband principle was to fulfill the Federal Communications Commission (FCC) mandated reduction of channel assignments from 25 KHz to 12.5 KHz to 6.25 KHz channel assignments. This would allow for four times the number of assigned users within an allowable band, otherwise known as spectrum efficiency.

Phase 1

P25 Phase 1 is the first step in the process. It allows for a migration to a 12.5 KHz digital channel, and is backward compatible and allowed to converse with analog radio systems.

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The equipment used for the digital traffic is continuous four-level frequency modulation (C4FM). In digital mode, it produces a baud rate of 9600 baud, or bits per second.

Phase 2

Phase 2 has a different modulation process, called finalized quadrature phase-shift keying (CQPSK). This is a technique in which the digitized signal is created at a rate of 4800 baud. This allows for two voice or data signals to be super-imposed into the 12.5 KHz channel, or, technically, 6.25 KHz per channel.

The final planned migration of Phase 2 is to convert to a time division multiple access (TDMA) technology. This technique “samples” each of two voice users alternately, and creates a composite signal of both. Two-slot TDMA allows for two voice users to be on the same radio, technically reducing the equipment needed per channel.

The advantage of this TDMA process is that one base station can now accept and process two voice or data users, thereby reducing infrastructure costs.

Conclusion

In the ever changing world of communications, it has, in the past, been the vendors that have controlled the technology of innovation. That control has created a quagmire of differing technologies, as well as incompatible systems. P25 has been designed and created to eliminate those incompatibilities. The catchword of today and tomorrow is “interoperability,” and P25 has been deemed the standard through which that interoperable breakthrough has been accomplished.

www.lrkimball.com