Misplaced Pages

#263736

110-486: Starting around 2012, products became available with the newer phase 2 modulation protocol, the older protocol known as P25 became P25 phase 1. P25 phase 2 products use the more advanced AMBE2+ vocoder, which allows audio to pass through a more compressed bitstream and provides two TDMA voice channels in the same RF bandwidth (12.5 kHz), while phase 1 can provide only one voice channel. The two protocols are not compatible. However, P25 Phase 2 infrastructure can provide

220-441: A constellation diagram , showing the amplitude of the I signal at the x-axis, and the amplitude of the Q signal at the y-axis, for each symbol. PSK and ASK, and sometimes also FSK, are often generated and detected using the principle of QAM. The I and Q signals can be combined into a complex-valued signal I + jQ (where j is the imaginary unit ). The resulting so called equivalent lowpass signal or equivalent baseband signal

330-488: A digital signal consisting of a sequence of binary digits (bits), a bitstream , on the carrier, by means of mapping bits to elements from a discrete alphabet to be transmitted. This alphabet can consist of a set of real or complex numbers , or sequences, like oscillations of different frequencies, so-called frequency-shift keying (FSK) modulation. A more complicated digital modulation method that employs multiple carriers, orthogonal frequency-division multiplexing (OFDM),

440-506: A memorandum of understanding to collaborate on the United States Standards Strategy. The determinates of whether an NSB for a particular economy is a public or private sector body may include the historical and traditional roles that the private sector fills in public affairs in that economy or the development stage of that economy. A national standards body (NSB) generally refers to one standardization organization that

550-531: A "dynamic transcoder" feature that translates between Phase 1 and Phase 2 as needed. In addition to this, phase 2 radios are backwards compatible with phase 1 modulation and analog FM modulation, per the standard. The European Union has created the Terrestrial Trunked Radio (TETRA) and Digital mobile radio (DMR) protocol standards, which fill a similar role to Project 25. Public safety radios have been upgraded from analog FM to digital since

660-513: A challenging topic in telecommunication systems and computer engineering. Such systems have many civil and military applications. Moreover, blind recognition of modulation type is an important problem in commercial systems, especially in software-defined radio . Usually in such systems, there are some extra information for system configuration, but considering blind approaches in intelligent receivers, we can reduce information overload and increase transmission performance. Obviously, with no knowledge of

770-407: A company offers a product that is "compliant" with a standard. When an organization develops standards that may be used openly, it is common to have formal rules published regarding the process. This may include: Though it can be a tedious and lengthy process, formal standard setting is essential to developing new technologies. For example, since 1865, the telecommunications industry has depended on

880-534: A cosine waveform) and a quadrature phase signal (or Q, with an example being a sine wave) are amplitude modulated with a finite number of amplitudes and then summed. It can be seen as a two-channel system, each channel using ASK. The resulting signal is equivalent to a combination of PSK and ASK. In all of the above methods, each of these phases, frequencies or amplitudes are assigned a unique pattern of binary bits . Usually, each phase, frequency or amplitude encodes an equal number of bits. This number of bits comprises

990-406: A different television channel , are transported through a single cable to customers. Since each carrier occupies a different frequency, the channels do not interfere with each other. At the destination end, the carrier signal is demodulated to extract the information bearing modulation signal. A modulator is a device or circuit that performs modulation. A demodulator (sometimes detector )

1100-566: A disaster when basic infrastructure has failed. To meet the growing demands of public safety digital radio communication, the United States Federal Communications Commission (FCC) at the direction of the United States Congress initiated a 1988 inquiry for recommendations from users and manufacturers to improve existing communication systems. Based on the recommendations, to find solutions that best serve

1210-409: A feature of P25, referred to as "presence". The report's authors concluded by saying "It is reasonable to wonder why this protocol, which was developed over many years and is used for sensitive and critical applications, is so difficult to use and so vulnerable to attack." The authors separately issued a set of recommendations for P25 users to mitigate some of the problems found. These include disabling

SECTION 10

#1732872368264

1320-509: A hierarchical fashion in terms of national, regional and international scope; international organizations tend to have as members national organizations; and standards emerging at national level (such as BS 5750 ) can be adopted at regional levels (BS 5750 was adopted as EN 29000) and at international levels (BS 5750 was adopted as ISO 9000). Unless adopted by a government, standards carry no force in law. However, most jurisdictions have truth in advertising laws, and ambiguities can be reduced if

1430-418: A large antenna is not practical. In radio communication , the modulated carrier is transmitted through space as a radio wave to a radio receiver . Another purpose of modulation is to transmit multiple channels of information through a single communication medium , using frequency-division multiplexing (FDM). For example, in cable television (which uses FDM), many carrier signals, each modulated with

1540-840: A large variety of independent international standards organizations such as the ASME , ASTM International , the International Commission on Illumination (CIE) , the IEEE , the Internet Engineering Task Force (IETF), SAE International , TAPPI , the World Wide Web Consortium (W3C), and the Universal Postal Union (UPU) develop and publish standards for a variety of international uses. In many such cases, these international standards organizations are not based on

1650-627: A message consisting of two digital bits in this example, the bit rate is twice the symbol rate, i.e. 2000 bits per second. According to one definition of digital signal , the modulated signal is a digital signal. According to another definition, the modulation is a form of digital-to-analog conversion . Most textbooks would consider digital modulation schemes as a form of digital transmission , synonymous to data transmission; very few would consider it as analog transmission . The most fundamental digital modulation techniques are based on keying : In QAM, an in-phase signal (or I, with one example being

1760-429: A narrowband analog signal over an analog baseband channel as a two-level signal by modulating a pulse wave . Some pulse modulation schemes also allow the narrowband analog signal to be transferred as a digital signal (i.e., as a quantized discrete-time signal ) with a fixed bit rate, which can be transferred over an underlying digital transmission system, for example, some line code . These are not modulation schemes in

1870-425: A number of reasons. 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 6.25 kHz "bandwidth equivalent" which satisfies an FCC requirement for voice transmissions to occupy less bandwidth. Voice traffic on a Phase 2 system transmits with

1980-470: A particular country, while others have been built from scratch by groups of experts who sit on various technical committees (TCs). These three organizations together comprise the World Standards Cooperation (WSC) alliance. ISO is composed of the national standards bodies (NSBs), one per member economy. The IEC is similarly composed of national committees, one per member economy. In some cases,

2090-589: A permanent agency of the United Nations , in which governments are the primary members, although other organizations (such as non-governmental organizations and individual companies) can also hold a form of direct membership status in the ITU as well. Another example of a treaty-based international standards organization with government membership is the Codex Alimentarius Commission . In addition to these,

2200-408: A product or process is safe for humans, animals, and the environment. The subject of their work can be narrow or broad. Another area of interest is in defining how the behavior and performance of products is measured and described in data sheets. Overlapping or competing standards bodies tend to cooperate purposefully, by seeking to define boundaries between the scope of their work, and by operating in

2310-594: A proper class. Another recent approach is based on feature extraction. Digital baseband modulation changes the characteristics of a baseband signal, i.e., one without a carrier at a higher frequency. This can be used as equivalent signal to be later frequency-converted to a carrier frequency, or for direct communication in baseband. The latter methods both involve relatively simple line codes , as often used in local buses, and complicated baseband signalling schemes such as used in DSL . Pulse modulation schemes aim at transferring

SECTION 20

#1732872368264

2420-1166: A proposal to form a new global standards body. In October 1946, ISA and UNSCC delegates from 25 countries met in London and agreed to join forces to create the new International Organization for Standardization ; the new organization officially began operations in February ;1947. Standards organizations can be classified by their role, position, and the extent of their influence on the local, national, regional, and global standardization arena. By geographic designation, there are international, regional, and national standards bodies (the latter often referred to as NSBs). By technology or industry designation, there are standards developing organizations (SDOs) and also standards setting organizations (SSOs) also known as consortia. Standards organizations may be governmental, quasi-governmental or non-governmental entities. Quasi- and non-governmental standards organizations are often non-profit organizations. Broadly, an international standards organization develops international standards (this does not necessarily restrict

2530-560: A radio) at the time. However P25 radio prices are rapidly approaching parity with TETRA radio prices through increased competition in the P25 market. 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. Some P25 networks also allow intelligent migration from

2640-427: A sequence of binary digits, a bitstream from a computer. This carrier wave usually has a much higher frequency than the message signal does. This is because it is impractical to transmit signals with low frequencies. Generally, to receive a radio wave one needs a radio antenna with length that is one-fourth of wavelength. For low frequency radio waves, wavelength is on the scale of kilometers and building such

2750-709: A synchronization source; therefore direct radio to radio communication resorts to conventional FDMA digital operation. Multi-band subscriber radios can also operate on narrow-band FM as a lowest common denominator between almost any two way radios. This makes analog narrow-band FM the de facto "interoperability" mode for some time. Originally the implementation of Phase 2 was planned to split the 12.5 kHz channel into two 6.25 kHz slots, or Frequency-Division Multiple Access (FDMA). However it proved more advantageous to use existing 12.5 kHz frequency allocations in Time Division Multiple Access (TDMA) mode for

2860-410: A technological baseline for future research and product development. Formal standard setting through standards organizations has numerous benefits for consumers including increased innovation, multiple market participants, reduced production costs, and the efficiency effects of product interchangeability. To support the standard development process, ISO published Good Standardization Practices (GSP) and

2970-538: A timely fashion. In some cases, radio communication systems are incompatible and inoperable not just within a jurisdiction but within departments or agencies in the same community. Non-operability occurs due to use of outdated equipment, limited availability of radio frequencies, isolated or independent planning, lack of coordination, and cooperation, between agencies, community priorities competing for resources, funding and ownership, and control of communications systems. Recognizing and understanding this need, Project 25 (P25)

3080-496: A university may have copies of technical standards on hand. Major libraries in large cities may also have access to many technical standards. Some users of standards mistakenly assume that all standards are in the public domain . This assumption is correct only for standards produced by the central governments whose publications are not amenable to copyright or to organizations that issue their standard under an open license. Any standards produced by non-governmental entities remain

3190-565: A vendor to claim a product is "P25 CAP compliant" or "P25 compliant with the Statement of Requirements (P25 SOR)" At the Securecomm 2011 conference in London, security researcher Steve Glass presented a paper, written by himself and co-author Matt Ames, that explained how DES-OFB and Motorola's proprietary ADP (RC4 based) ciphers were vulnerable to brute force key recovery. This research was the result of

3300-559: A voluntary program, allows suppliers to publicly attest to their products' compliance. Independent, accredited labs test vendor's P25 radios for compliance to P25 Standards, derived from TIA-102 Standards and following TIA-TR8 testing procedures. Only approved products may be purchased using US federal grant dollars. Generally, non-approved products should not be trusted to be meet P25 standards for performance, conformance, and interoperability. P25 product labeling varies. "P25" and "P25 compliant" mean nothing while high standards apply for

3410-425: Is synchronous modulation . The most common digital modulation techniques are: MSK and GMSK are particular cases of continuous phase modulation. Indeed, MSK is a particular case of the sub-family of CPM known as continuous-phase frequency-shift keying (CPFSK) which is defined by a rectangular frequency pulse (i.e. a linearly increasing phase pulse) of one-symbol-time duration (total response signaling). OFDM

Project 25 - Misplaced Pages Continue

3520-526: Is "impressed" on the carrier. Examples are amplitude modulation (AM) in which the amplitude (strength) of the carrier wave is varied by the modulation signal, and frequency modulation (FM) in which the frequency of the carrier wave is varied by the modulation signal. These were the earliest types of modulation , and are used to transmit an audio signal representing sound in AM and FM radio broadcasting . More recent systems use digital modulation , which impresses

3630-417: Is a circuit that performs demodulation , the inverse of modulation. A modem (from mod ulator– dem odulator), used in bidirectional communication, can perform both operations. The lower frequency band occupied by the modulation signal is called the baseband , while the higher frequency band occupied by the modulated carrier is called the passband . In analog modulation , an analog modulation signal

3740-444: Is a complex-valued representation of the real-valued modulated physical signal (the so-called passband signal or RF signal ). These are the general steps used by the modulator to transmit data: At the receiver side, the demodulator typically performs: As is common to all digital communication systems, the design of both the modulator and demodulator must be done simultaneously. Digital modulation schemes are possible because

3850-596: Is also being used in other countries worldwide including Australia, New Zealand, Brazil, Canada, India and Russia. As of mid-2004 there were 660 networks with P25 deployed in 54 countries. At the same time, in 2005, the European Terrestrial Trunked Radio (TETRA) was deployed in sixty countries, and it is the preferred choice in Europe, China, and other countries. This was largely based on TETRA systems being many times cheaper than P25 systems ($ 900 vs $ 6,000 for

3960-434: Is automatically assigned to one or more voice channels by a Repeater or Base Station. The protocol supports the use of Data Encryption Standard (DES) encryption (56 bit), 2-key Triple-DES encryption, three-key Triple-DES encryption, Advanced Encryption Standard (AES) encryption at up to 256 bits keylength, RC4 ( 40 bits , sold by Motorola as Advanced Digital Privacy ), or no encryption. The protocol also supports

4070-425: Is based on the idea of frequency-division multiplexing (FDM), but the multiplexed streams are all parts of a single original stream. The bit stream is split into several parallel data streams, each transferred over its own sub-carrier using some conventional digital modulation scheme. The modulated sub-carriers are summed to form an OFDM signal. This dividing and recombining help with handling channel impairments. OFDM

4180-410: Is called a Network Access Code (NAC) which is included outside of the digital voice frame. This is a 12-bit code that prefixes every packet of data sent, including those carrying voice transmissions. The NAC is a feature similar to CTCSS or DCS for analog radios. 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

4290-407: Is considered as a modulation technique rather than a multiplex technique since it transfers one bit stream over one communication channel using one sequence of so-called OFDM symbols. OFDM can be extended to multi-user channel access method in the orthogonal frequency-division multiple access (OFDMA) and multi-carrier code-division multiple access (MC-CDMA) schemes, allowing several users to share

4400-469: Is inherently jam-resistant. An optimal spread spectrum system can require an effective jammer to use 1,000 times as much power (30 dB more) as the individual communicators. According to the report, a P25 jammer could effectively operate at 1/25th the power (14 dB less) than the communicating radios. The authors developed a proof-of-concept jammer using a Texas Instruments CC1110 single chip radio, found in an inexpensive toy. Certain metadata fields in

4510-598: Is that country's member of the ISO . A standards developing organization (SDO) is one of the thousands of industry- or sector-based standards organizations that develop and publish industry specific standards. Some economies feature only an NSB with no other SDOs. Large economies like the United States and Japan have several hundred SDOs, many of which are coordinated by the central NSBs of each country (ANSI and JISC in this case). In some cases, international industry-based SDOs such as

Project 25 - Misplaced Pages Continue

4620-421: Is the process of varying one or more properties of a periodic waveform , called the carrier signal , with a separate signal called the modulation signal that typically contains information to be transmitted. For example, the modulation signal might be an audio signal representing sound from a microphone , a video signal representing moving images from a video camera , or a digital signal representing

4730-621: Is transmitted along with the digital signal being transmitted. Since the NAC is a three-hexadecimal-digit number (12 bits), there are 4,096 possible NACs for programming, far more than all analog methods combined. Three of the possible NACs have special functions: 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 25. It

4840-465: Is used in WiFi networks, digital radio stations and digital cable television transmission. In analog modulation, the modulation is applied continuously in response to the analog information signal. Common analog modulation techniques include: In digital modulation, an analog carrier signal is modulated by a discrete signal. Digital modulation methods can be considered as digital-to-analog conversion and

4950-697: Is voice data generated by the IMBE codec, 2,800 is forward error correction, and 2,400 is signalling and other control functions. Receivers designed for the C4FM standard can also demodulate the "Compatible quadrature phase shift keying " (CQPSK) standard, as the parameters of the CQPSK signal were chosen to yield the same signal deviation at symbol time as C4FM. 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

5060-830: The African Organisation for Standardisation (ARSO), the Arabic industrial development and mining organization (AIDMO), and others. In the European Union, only standards created by CEN, CENELEC, and ETSI are recognized as European standards (according to Regulation (EU) No 1025/2012 ), and member states are required to notify the European Commission and each other about all the draft technical regulations concerning ICT products and services before they are adopted in national law. These rules were laid down in Directive 98/34/EC with

5170-705: The CIE , the IEEE and the Audio Engineering Society (AES) may have direct liaisons with international standards organizations, having input to international standards without going through a national standards body. SDOs are differentiated from standards setting organizations (SSOs) in that SDOs may be accredited to develop standards using open and transparent processes. Developers of technical standards are generally concerned with interface standards , which detail how products interconnect with each other, and safety standards , which established characteristics ensure that

5280-685: The GCC Standardization Organization (GSO) for Arab States of the Persian Gulf . In general, each country or economy has a single recognized national standards body (NSB). A national standards body is likely the sole member from that economy in ISO; ISO currently has 161 members. National standards bodies usually do not prepare the technical content of standards, which instead is developed by national technical societies. NSBs may be either public or private sector organizations, or combinations of

5390-537: The Hayes command set developed by Hayes , Apple 's TrueType font design and the PCL protocol used by Hewlett-Packard in the computer printers they produced. Normally, the term standards organization is not used to refer to the individual parties participating within the standards developing organization in the capacity of founders, benefactors , stakeholders , members or contributors, who themselves may function as or lead

5500-513: The ITU to establish the telecommunications standards that have been adopted worldwide. The ITU has created numerous telecommunications standards including telegraph specifications, allocation of telephone numbers, interference protection, and protocols for a variety of communications technologies. The standards that are created through standards organizations lead to improved product quality, ensured interoperability of competitors' products, and they provide

5610-624: The WTO Technical Barriers to Trade (TBT) Committee published the "Six Principles" guiding members in the development of international standards. Some standards – such as the SIF Specification in K12 education – are managed by a non-profit organizations composed of public entities and private entities working in cooperation that then publish the standards under an open license at no charge and requiring no registration. A technical library at

SECTION 50

#1732872368264

5720-689: The World Health Organization Guidelines in health, or ITU Recommendations in ICT and being publicly funded, are freely available for consideration and use worldwide. In 1904, Crompton represented Britain at the Louisiana Purchase Exposition in St. Louis , Missouri , as part of a delegation by the Institute of Electrical Engineers . He presented a paper on standardization, which

5830-462: The World Wide Web Consortium (W3C), whose standards for HTML , CSS , and XML are used universally. There are also community-driven associations such as the Internet Engineering Task Force (IETF), a worldwide network of volunteers who collaborate to set standards for internet protocols. Some industry-driven standards development efforts don't even have a formal organizational structure. They are projects funded by large corporations. Among them are

5940-406: The intellectual property of their developers (unless specifically designed otherwise) and are protected, just like any other publications , by copyright laws and international treaties . However, the intellectual property extends only to the standard itself and not to its use. For instance if a company sells a device that is compliant with a given standard, it is not liable for further payment to

6050-411: The symbol that is represented by the particular phase, frequency or amplitude. If the alphabet consists of M = 2 N {\displaystyle M=2^{N}} alternative symbols, each symbol represents a message consisting of N bits. If the symbol rate (also known as the baud rate ) is f S {\displaystyle f_{S}} symbols/second (or baud ),

6160-466: The 1990s because of an increased use of data on radio systems for such features as GPS location, trunking , text messaging, metering, and encryption. Various user protocols and different public safety radio spectrum made it difficult for Public Safety agencies to achieve interoperability and widespread acceptance. However, lessons learned during disasters the United States faced in the past decades have forced agencies to assess their requirements during

6270-727: The ACCORDION 1.3, BATON , Firefly , MAYFLY and SAVILLE Type 1 ciphers. P25's Suite of Standards specify eight open interfaces between the various components of a land mobile radio system. These interfaces are: P25-compliant technology has been deployed over two main phases with future phases yet to be finalized. Phase 1 radio systems operate in 12.5 kHz digital mode using a single user per channel access method. Phase 1 radios use Continuous 4 level FM (C4FM) modulation—a special type of 4 FSK modulation—for digital transmissions at 4,800 baud and 2 bits per symbol, yielding 9,600 bits per second total channel throughput. Of this 9,600, 4,400

6380-968: The AMBE voice coder that uses half the rate of the Phase 1 IMBE voice coders. From 2000 to 2009, the European Telecommunications Standards Institute (ETSI) and TIA were working collaboratively on the Public Safety Partnership Project or Project MESA (Mobility for Emergency and Safety Applications), which sought to define a unified set of requirements for a next-generation aeronautical and terrestrial digital wideband/broadband radio standard that could be used to transmit and receive voice, video, and high-speed data in wide-area, multiple-agency networks deployed by public safety agencies. The final functional and technical requirements have been released by ETSI and were expected to shape

6490-696: The ARINC Standards. Regional standards bodies also exist, such as the European Committee for Standardization (CEN), the European Committee for Electrotechnical Standardization (CENELEC), the European Telecommunications Standards Institute (ETSI), and the Institute for Reference Materials and Measurements (IRMM) in Europe, the Pacific Area Standards Congress (PASC), the Pan American Standards Commission (COPANT),

6600-871: The National Communications System (NCS), and standardized under the Telecommunications Industry Association (TIA)... The P25 suite of standards involves digital Land Mobile Radio ( LMR ) services for local, state/provincial and national (federal) public safety organizations and agencies... P25 is applicable to LMR equipment authorized or licensed, in the U.S., under NTIA or FCC rules and regulations. 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. P25-compliant systems are being increasingly adopted and deployed throughout

6710-707: The OP25 project which uses GNU Radio and the Ettus Universal Software Radio Peripheral (USRP) to implement an open source P25 packet sniffer and analyzer. The OP25 project was founded by Steve Glass in early 2008 while he was performing research into wireless networks as part of his PhD thesis. The paper is available for download from the NICTA website. In 2011, the Wall Street Journal published an article describing research into security flaws of

SECTION 60

#1732872368264

6820-457: The Project 25 protocol are not encrypted, allowing an attacker to perform traffic analysis to identify users. Because Project 25 radios respond to bad data packets addressed to them with a retransmission request, an attacker can deliberately send bad packets forcing a specific radio to transmit even if the user is attempting to maintain radio silence . Such tracking by authorized users is considered

6930-401: The Project 25 system, some specific to the way it has been implemented and some inherent in the security design. The report did not find any breaks in the P25 encryption; however, they observed large amounts of sensitive traffic being sent in the clear due to implementations problems. They found switch markings for secure and clear modes difficult to distinguish (∅ vs. o). This is exacerbated by

7040-517: The QAM modulation principle are used to drive switching amplifiers with these FM and other waveforms, and sometimes QAM demodulators are used to receive the signals put out by these switching amplifiers. Automatic digital modulation recognition in intelligent communication systems is one of the most important issues in software-defined radio and cognitive radio . According to incremental expanse of intelligent receivers, automatic modulation recognition becomes

7150-580: The TIA-102 series of documents, which now include 49 separate parts on Land Mobile Radio and TDMA implementations of the technology for public safety. Project 25 (P25) is a set of standards produced through the joint efforts of the Association of Public Safety Communications Officials International (APCO), the National Association of State Telecommunications Directors (NASTD), selected federal agencies and

7260-503: The United States, as well as other countries. Radios can communicate in analog mode with legacy radios, and in either digital or analog mode with other P25 radios. Additionally, the deployment of P25-compliant systems will allow for a high degree of equipment interoperability and compatibility. P25 standards use the proprietary Improved Multi-Band Excitation (IMBE) and Advanced Multi-Band Excitation (AMBE+2) voice codecs which were designed by Digital Voice Systems, Inc. to encode/decode

7370-426: The analog audio signals. 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 may be used in "talk around" mode without any intervening equipment between two radios, in conventional mode where two radios communicate through a repeater or base station without trunking or in a trunked mode where traffic

7480-797: The analog radios to digital radios operating within the same network. 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. In practice, interoperable communications isn't achievable without effective governance, standardized operating procedures, effective training and exercises, and inter-jurisdictional coordination. The difficulties inherent in developing P25 networks using features such as digital voice, encryption, or trunking sometimes result in feature-backlash and organizational retreat to minimal "feature-free" P25 implementations which fulfill

7590-493: The body's first President. The International Federation of the National Standardizing Associations (ISA) was founded in 1926 with a broader remit to enhance international cooperation for all technical standards and specifications. The body was suspended in 1942 during World War II . After the war, ISA was approached by the recently formed United Nations Standards Coordinating Committee (UNSCC) with

7700-504: The contributions of other engineers, accomplished a modest amount of industry standardization; some companies' in-house standards also began to spread more widely within their industries. Joseph Whitworth 's screw thread measurements were adopted as the first (unofficial) national standard by companies around Britain in 1841. It came to be known as the British Standard Whitworth , and was widely adopted in other countries. By

7810-510: The conventional sense since they are not channel coding schemes, but should be considered as source coding schemes, and in some cases analog-to-digital conversion techniques. Standards organization A standards organization , standards body , standards developing organization ( SDO ), or standards setting organization ( SSO ) is an organization whose primary function is developing, coordinating, promulgating, revising, amending, reissuing, interpreting, or otherwise contributing to

7920-442: The corresponding demodulation or detection as analog-to-digital conversion. The changes in the carrier signal are chosen from a finite number of M alternative symbols (the modulation alphabet ). A simple example: A telephone line is designed for transferring audible sounds, for example, tones, and not digital bits (zeros and ones). Computers may, however, communicate over a telephone line by means of modems, which are representing

8030-797: The country, and enabled the markets to act more rationally and efficiently, with an increased level of cooperation. After the First World War , similar national bodies were established in other countries. The Deutsches Institut für Normung was set up in Germany in 1917, followed by its counterparts, the American National Standard Institute and the French Commission Permanente de Standardisation , both in 1918. Several international organizations create international standards , such as Codex Alimentarius in food,

8140-407: The data rate is N f S {\displaystyle Nf_{S}} bit/second. For example, with an alphabet consisting of 16 alternative symbols, each symbol represents 4 bits. Thus, the data rate is four times the baud rate. In the case of PSK, ASK or QAM, where the carrier frequency of the modulated signal is constant, the modulation alphabet is often conveniently represented on

8250-439: The digital bits by tones, called symbols. If there are four alternative symbols (corresponding to a musical instrument that can generate four different tones, one at a time), the first symbol may represent the bit sequence 00, the second 01, the third 10 and the fourth 11. If the modem plays a melody consisting of 1000 tones per second, the symbol rate is 1000 symbols/second, or 1000 baud . Since each tone (i.e., symbol) represents

8360-510: The end of the 19th century differences in standards between companies was making trade increasingly difficult and strained. For instance, in 1895 an iron and steel dealer recorded his displeasure in The Times : "Architects and engineers generally specify such unnecessarily diverse types of sectional material or given work that anything like economical and continuous manufacture becomes impossible. In this country no two professional men are agreed upon

8470-413: The entire frame. As a result, an attacker can effectively jam Project 25 signals with average power levels much lower than the power levels used for communication. Such attacks can be targeted at encrypted transmissions only, forcing users to transmit in the clear. Because Project 25 radios are designed to work in existing two-way radio frequency channels, they cannot use spread spectrum modulation, which

8580-411: The fact that P25 radios when set to secure mode continue to operate without issuing a warning if another party switches to clear mode. In addition, the report authors said many P25 systems change keys too often, increasing the risk that an individual radio on a net may not be properly keyed, forcing all users on the net to transmit in the clear to maintain communications with that radio. One design choice

8690-480: The foreword with a statement like the following: "Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights". If the standards organization is aware that parts of a given standard fall under patent protection, it will often require the patent holder to agree to Reasonable and non-discriminatory licensing before including it in

8800-407: The full 12.5 kHz per frequency allocation, as a Phase 1 system does, however it does so at a faster data rate of 12 kbit/s allowing two simultaneous voice transmissions. As such subscriber radios also transmit with the full 12.5 kHz, but in an on/off repeating fashion resulting in half the transmission and thus an equivalent of 6.25 kHz per each radio. This is accomplished using

8910-619: The goal of providing transparency and control with regard to technical regulations. Sub-regional standards organizations also exist such as the MERCOSUR Standardization Association (AMN), the CARICOM Regional Organisation for Standards and Quality (CROSQ), and the ASEAN Consultative Committee for Standards and Quality (ACCSQ), EAC East Africa Standards Committee www.eac-quality.net , and

9020-401: The inability of their developers to keep abreast with the technological innovation. As a result, a new class of standards setters appeared on the standardization arena: the industry consortia or standards setting organizations (SSOs), which are also referred to as private standards . Despite having limited financial resources, some of them enjoy truly international acceptance. One example is

9130-456: The letter of any Project 25 migration requirement without realizing the benefits thereof. Additionally, while not a technical issue per se, frictions often result from the unwieldy bureaucratic inter-agency processes that tend to develop in order to coordinate interoperability decisions. The United States DHS 's Project 25 Compliance Assessment Program (P25 CAP) aims for interoperability among different vendors by testing to P25 Standards. P25 CAP,

9240-518: The location of a radio's user. With other systems, jammers have to expend a lot of power to block communications, but the P25 radios allow jamming at relatively low power, enabling the researchers to prevent reception using a $ 30 toy pager designed for pre-teens." The report was presented at the 20th USENIX Security Symposium in San Francisco in August 2011. The report noted a number of security flaws in

9350-406: The messages sent over the radios are sent in segments, and blocking just a portion of these segments can result in the entire message being jammed. "Their research also shows that the radios can be effectively jammed (single radio, short range) using a highly modified pink electronic child's toy and that the standard used by the radios 'provides a convenient means for an attacker' to continuously track

9460-466: The national committee to the IEC of an economy may also be the ISO member from that country or economy. ISO and IEC are private international organizations that are not established by any international treaty. Their members may be non-governmental organizations or governmental agencies, as selected by ISO and IEC (which are privately established organizations). The ITU is a treaty-based organization established as

9570-495: The needs of public safety management, in October 1989 APCO Project 25 came into existence in a coalition with: A steering committee consisting of representatives from the above-mentioned agencies along with FPIC ( Department of Homeland Security Federal Partnership for Interoperable Communication), Coast Guard and the Department of Commerce 's National Institute of Standards and Technology (NIST), Office of Law Enforcement Standards

9680-838: The next phases of American Project 25 and European DMR, dPMR , and TETRA, but no interest from the industry followed, since the requirements could not be met by available commercial off-the-shelf technology, and the project was closed in 2010. During the United States 2008 wireless spectrum auction , the FCC allocated 20 MHz of the 700 MHz UHF radio band spectrum freed in the digital TV transition to public safety networks. The FCC expects providers to employ LTE for high-speed data and video applications. P25 systems do not have to resort to using in band signaling such as Continuous Tone-Coded Squelch System (CTCSS) tone or Digital-Coded Squelch (DCS) codes for access control. Instead they use what

9790-472: The principle of one member per country. Rather, membership in such organizations is open to those interested in joining and willing to agree to the organization's by-laws – having either organizational/corporate or individual technical experts as members. The Airlines Electronic Engineering Committee (AEEC) was formed in 1949 to prepare avionics system engineering standards with other aviation organizations RTCA, EUROCAE, and ICAO. The standards are widely known as

9900-790: The purpose of safety or for consumer protection act from deceitful practices. The term formal standard refers specifically to a specification that has been approved by a standards setting organization. The term de jure standard refers to a standard mandated by legal requirements or refers generally to any formal standard. In contrast, the term de facto standard refers to a specification (or protocol or technology) that has achieved widespread use and acceptance – often without being approved by any standards organization (or receiving such approval only after it already has achieved widespread use). Examples of de facto standards that were not approved by any standards organizations (or at least not approved until after they were in widespread de facto use) include

10010-541: The same physical medium by giving different sub-carriers or spreading codes to different users. Of the two kinds of RF power amplifier , switching amplifiers ( Class D amplifiers ) cost less and use less battery power than linear amplifiers of the same output power. However, they only work with relatively constant-amplitude-modulation signals such as angle modulation (FSK or PSK) and CDMA , but not with QAM and OFDM. Nevertheless, even though switching amplifiers are completely unsuitable for normal QAM constellations, often

10120-448: The same with Company C's sphygmomanometer as it does with Company D's, or that all shirts that should not be ironed have the same icon (a clothes iron crossed out with an X) on the label. Most standards are voluntary in the sense that they are offered for adoption by people or industry without being mandated in law. Some standards become mandatory when they are adopted by regulators as legal requirements in particular domains, often for

10230-436: The secure/clear switch, using Network Access Codes to segregate clear and encrypted traffic, and compensating for the unreliability of P25 over-the-air rekeying by extending key life. P25 and TETRA are used in more than 53 countries worldwide for both public safety and private sector radio networks. There are some differences in features and capacities: Modulation In electronics and telecommunications , modulation

10340-399: 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. To improve spectrum use, P25 Phase 2

10450-541: The size and weight of a girder to employ for given work". The Engineering Standards Committee was established in London in 1901 as the world's first national standards body. It subsequently extended its standardization work and became the British Engineering Standards Association in 1918, adopting the name British Standards Institution in 1931 after receiving its Royal Charter in 1929. The national standards were adopted universally throughout

10560-454: The standard. Such an agreement is regarded as a legally binding contract, as in the 2012 case Microsoft v. Motorola . The ever-quickening pace of technology evolution is now more than ever affecting the way new standards are proposed, developed and implemented. Since traditional, widely respected standards organizations tend to operate at a slower pace than technology evolves, many standards they develop are becoming less relevant because of

10670-455: The standards organization except in the special case when the organization holds patent rights or some other ownership of the intellectual property described in the standard. It is, however, liable for any patent infringement by its implementation, just as with any other implementation of technology. The standards organizations give no guarantees that patents relevant to a given standard have been identified. ISO standards draw attention to this in

10780-501: The standards organizations. The implementation of standards in industry and commerce became highly important with the onset of the Industrial Revolution and the need for high-precision machine tools and interchangeable parts . Henry Maudslay developed the first industrially practical screw-cutting lathe in 1800, which allowed for the standardization of screw thread sizes for the first time. Maudslay's work, as well as

10890-494: The system, including a user interface that makes it difficult for users to recognize when transceivers are operating in secure mode. According to the article, "(R)esearchers from the University of Pennsylvania overheard conversations that included descriptions of undercover agents and confidential informants , plans for forthcoming arrests and information on the technology used in surveillance operations." The researchers found that

11000-496: The transmitted data and many unknown parameters at the receiver, such as the signal power, carrier frequency and phase offsets, timing information, etc., blind identification of the modulation is made fairly difficult. This becomes even more challenging in real-world scenarios with multipath fading, frequency-selective and time-varying channels. There are two main approaches to automatic modulation recognition. The first approach uses likelihood-based methods to assign an input signal to

11110-549: The transmitter-receiver pair has prior knowledge of how data is encoded and represented in the communications system. In all digital communication systems, both the modulator at the transmitter and the demodulator at the receiver are structured so that they perform inverse operations. Asynchronous methods do not require a receiver reference clock signal that is phase synchronized with the sender carrier signal . In this case, modulation symbols (rather than bits, characters, or data packets) are asynchronously transferred. The opposite

11220-538: The two. For example, the Standards Council of Canada is a Canadian Crown Corporation , Dirección General de Normas is a governmental agency within the Mexican Ministry of Economy, and ANSI is a 501(c)(3) non-profit U.S. organization with members from both the private and public sectors. The National Institute of Standards and Technology (NIST), the U.S. government's standards agency, cooperates with ANSI under

11330-1056: The use of other published standards internationally). There are many international standards organizations. The three largest and most well-established such organizations are the International Organization for Standardization (ISO), the International Electrotechnical Commission (IEC), and the International Telecommunication Union (ITU), which have each existed for more than 50 years (founded in 1947, 1906, and 1865, respectively) and are all based in Geneva , Switzerland . They have established tens of thousands of standards covering almost every conceivable topic. Many of these are then adopted worldwide replacing various incompatible "homegrown" standards. Many of these standards are naturally evolved from those designed in-house within an industry, or by

11440-440: The usefulness of technical standards to those who employ them. Such an organization works to create uniformity across producers, consumers, government agencies, and other relevant parties regarding terminology, product specifications (e.g. size, including units of measure), protocols, and more. Its goals could include ensuring that Company A's external hard drive works on Company B's computer, an individual's blood pressure measures

11550-657: Was developed for trunking systems using a 2-slot TDMA scheme and is now required for all new trunking systems in the 700 MHz band. Phase 2 uses the AMBE+2 voice codec to reduce the needed bitrate so that one voice channel will only require 6,000 bits per second (including error correction and signalling). Phase 2 is not backwards compatible with Phase 1 (due to the TDMA operation), although multi-mode TDMA radios and systems are capable of operating in Phase 1 mode when required, if enabled. A subscriber radio cannot use TDMA transmission without

11660-406: Was established to address the need for common digital public safety radio communications standards for first-responders and homeland security/emergency response professionals. The Telecommunications Industry Association 's TR-8 engineering committee facilitates such work through its role as an ANSI-accredited standards development organization (SDO) and has published the P25 suite of standards as

11770-439: Was established to decide the priorities and scope of technical development of P25. 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 transmit important information in

11880-428: Was initiated collaboratively by public safety agencies and manufacturers to address the issue with emergency communication systems . 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

11990-406: Was so well received that he was asked to look into the formation of a commission to oversee the process. By 1906, his work was complete and he drew up a permanent terms for the International Electrotechnical Commission . The body held its first meeting that year in London, with representatives from 14 countries. In honour of his contribution to electrical standardization, Lord Kelvin was elected as

12100-718: Was to use lower levels of error correction for portions of the encoded voice data that are deemed less critical for intelligibility. As a result, bit errors may be expected in typical transmissions, and while harmless for voice communication, the presence of such errors force the use of stream ciphers , which can tolerate bit errors, and prevents the use of a standard technique, message authentication codes (MACs), to protect message integrity from stream cipher attacks . The varying levels of error correction are implemented by breaking P25 message frames into subframes. This allows an attacker to jam entire messages by transmitting only during certain short subframes that are critical to reception of

#263736