These projects may be dams and highways or can be training programs and health care systems. The idea of this economic accounting originated with Jules Dupuit, a French engineer whose article is still worth reading. This act required that the U.
Interoperable emergency communication is integral to initial response, public health, community safety, national security and economic stability. Of all the problems experienced during disaster events, one of the most serious, is poor communication due to lack of appropriate and efficient means to collect, process and timely transmit important information.
In some cases, radio communication systems are incompatible and inoperable not just within a jurisdiction but within departments or agencies in the same community. P25 is a collaborative project to ensure that two-way radios are interoperable. The goal of P25 is to enable public safety responders to communicate with each other and, thus, achieve enhanced coordination, timely response, and efficient and effective use of communications equipment.
P25 is applicable to LMR equipment authorized or licensed, in the U.
Although developed primarily for North American public safety services, P25 technology and products are not limited to public safety alone and have also been selected and deployed in other private system application, worldwide. Additionally, the deployment of Pcompliant systems will allow for a high degree of equipment interoperability and compatibility.
It is rumored that the licensing cost for the voice-codecs that are used in P25 standard devices is the main reason that the cost of P25 compatible devices is so high.
P25 open interfaces[ edit ] P25's Suite of Standards specify eight open interfaces between the various components of a land mobile radio system.
Common Air Interface CAI — standard specifies the type and content of signals transmitted by compliant radios. Pcompliant technology has been deployed over two main phases with future phases yet to be finalized. Phase 1[ edit ] Phase 1 radio systems operate in Phase 1 radios use Continuous 4 level FM C4FM modulation—a special type of 4 FSK modulation  —for digital transmissions at 4, baud and 2 bits per symbol, yielding 9, bits per second total channel throughput.
Of this 9, 4, is voice data generated by the IMBE codec, 2, is forward error correction, and 2, is signalling and other control functions. Phase 1 uses the IMBE voice codec. These systems involve standardized service and facility specifications, ensuring that any manufacturers' compliant subscriber radio has access to the services described in such specifications.
Abilities include backward compatibility and interoperability with other systems, across system boundaries, and regardless of system infrastructure.
In addition, the P25 suite of standards provides an open interface to the radio frequency RF subsystem to facilitate interlinking of different vendors' systems. Phase 2[ edit ] To improve spectrum use, P25 Phase 2 was developed for trunking systems using a 2-slot TDMA scheme and is now required for all new trunking systems in the MHz band.
And subscriber radios can also resort to narrow-band FM being the least common denominator between almost any two way radio. This could make analog narrow-band FM the de facto "interoperability" mode for some time. Originally the implementation of Phase 2 was planned to use 6. However it proved more advantageous to use existing First it eliminated a huge administrative process of reallocating frequency assignments at the FCC for existing Phase 1 users.
Second it reduced the amount of base station transmitters as only one transmitter is needed to broadcast two voice slots.
And third it allowed subscriber radios to save battery life by only transmitting half the time which also yields the ability for the subscriber radio to listen and respond to system requests between transmissions.
Phase 2 is what is known as 6. Voice traffic on a Phase 2 system transmits with the full As such subscriber radios also transmit with the full This is a 12 bit code that prefixes every packet of data sent, including those carrying voice transmissions.
That is, radios can be programmed to only pass audio when receiving the correct NAC. NACs are programmed as a three-hexadecimal-digit code that is transmitted along with the digital signal being transmitted. Since the NAC is a three-hexadecimal-digit number 12 bitsthere are 4, possible NACs for programming, far more than all analog methods combined.
Three of the possible NACs have special functions: Adoption[ edit ] Adoption of these standards has been slowed by budget problems in the US; however, funding for communications upgrades from the Department of Homeland Security usually requires migrating to Project The majority of P25 networks are based in Northern America where it has the advantage that a P25 system has the same coverage and frequency bandwidth as the earlier analog systems that were in use so that channels can be easily upgraded one by one.
Both P25 and TETRA can offer varying degrees of functionality, depending on available radio spectrum, terrain and project budget.
While interoperability is a major goal of P25, many P25 features present interoperability challenges. In theory, all P25 compliant equipment is interoperable.Lecture #1 - Introduction to Information System 1. INFORMATION SYSTEM 2. A combination of Hardware Software Infrastructure and Trained personnelorganized to facilitate Planning Control Coordination and Decision Makingin an organization.
If you're curious about more governance details, we have description of Apache style governance. The Apache Community Development project is also here to help newcomers find their way around..
This page will give you an overview of everything you always wanted to know about the Apache Software Foundation but were afraid to ask.
This web site will educate the public about indoor environmental issues, including health risks and the means by which human exposures can be reduced. Introduction to NAICS. The North American Industry Classification System (NAICS) is the standard used by Federal statistical agencies in classifying business establishments for the purpose of collecting, analyzing, and publishing statistical data related to the U.S.
business economy. In the Software Development Project course, small student teams collaborate with community-based organizations to develop useful information system solutions to meet real management needs.
Each project team proposes, defines, designs and implements a working information system or application with the project client. An introduction is the first paragraph of a written research paper, or the first thing you say in an oral presentation, or the first thing people see, hear, or experience about your project.