Gps assisted


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Assisted GPS, A-GPS :: Radio-Electronics.Com

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- an overview, information or turorial about the basics of Assisted GPS (Global Positioning System) or A-GPS used to provide location based services used for cellualr technology and cellualr networks.

In recent years the importance of location services for mobile phone / cellular telecommunications has risen significantly. In particular Assisted GPS ( A-GPS ) has been chosen as the front runner of the possible location services to be used for cell phone applications where the E911 directive has mandated the accurate location of mobile phones by the emergency services.

A number of techniques are available by cell phone operators including TDOA (time difference of arrival), EOTD (Enhanced Observed Time Difference), AFLT (Advanced Forward Link Trilateration), and others. However it is assisted GPS ( A-GPS ) that has emerged as the front runner for cell phone applications.

Although the GPS or Global Positioning System is a particularly attractive option for providing accurate location, it requires some assistance in order to be able to provide the required service. As a result the Assisted GPS ( A-GPS ) technology has been developed, and in this way it is able to provide the required level of service for the mobile phone networks and operators.

GPS System

GPS is now widely used for gaining accurate positional information across the globe. Now low cost receivers and chips can be easily incorporated into many electronic items including mobile phones.

Note on GPS:

The GPS or Global Positioning System is a satellite based system that enables receivers or terminals on the Earth to gain accurate location information. The system uses a total of 24 active satellites which have been placed in six different equally spaced orbital planes with four satellites in each.

Click for a GPS tutorial

The satellites transmit signals that are received by the GPS receivers it and using this they are able to deduce their position. Each GPS satellite transmits data that includes information about its location and the current time. All GPS satellites synchronize operations so that these repeating signals are transmitted at effectively the same instant. The signals, moving at the speed of light, arrive at a GPS receiver at slightly different times because some satellites are further away than others. The distance to the GPS satellites can be determined by calculating the time it takes for the signals from the satellites to reach the receiver. When the receiver is able to calculate the distance from at least four GPS satellites, it is possible to determine the position of the GPS receiver in three dimensions.

The satellite transmits a variety of information. Some of the chief elements are known as ephemeris and almanac data. The ephemeris data is information that enables the precise orbit of the satellite to be calculated. The almanac data gives the approximate position of all the satellites in the constellation and from this the GPS receiver is able to discover which satellites are in view.

The problem with GPS for mobile phone applications is that signal levels are low, and the receiver needs to have a direct view of the satellite. This can cause problems when the phone is used in a building, or even in an urban area where a direct view of the satellite is masked. Additionally the time taken for the receiver to lock - Time To First Fix (TTFF) can be as much as ten minutes or more from switch on. This is not acceptable when emergency calls are being made as a much faster acquisition time is required. To achieve this assistance is required for the GPS receiver, thereby giving rise to the requirement for Assisted GPS.

Assisted GPS

The system known as Assisted GPS or A-GPS uses the mobile phone network to assist the GPS receiver in the mobile phone to overcome the problems associated with TTFF and the low signal levels that are encountered under some situations.

For A-GPS, the network provides the Ephemeris data to the cell phone GPS receiver and this improves the TTFF. This can be achieved by incorporating a GPS receiver into the base station itself, and as this is sufficiently close in position to the mobile the data received by the base station is sufficiently accurate to be transmitted on to the mobiles. The base station receiver is obviously on all the time, and will be located in a position where it can "see" the satellites.

The information provided can be either the Ephemeris data for visible satellites or, more helpfully the code phase and Doppler ranges over which the mobile has to search, i.e. 'acquisition data'. These ranges can be estimated as the position of the mobile is bounded because it must be within the cell served by the particular base station. This technique is able to improve the TTFF by many orders of magnitude.

Assisted GPS or A-GPS is also used to improve the performance within buildings where the GPS signals are by 20 dB or possibly more. Again by providing information to the GPS receiver in the mobile it is able to better correlate the signal being received from the satellite when the signal is low in strength. Using this technique it is possible to gain considerable increases in sensitivity and some manufacturers have claimed it is possible to receive signals down to power levels of around -159dBm. The base station supplies the receiver with navigation message bits - 'sensitivity data'.

Summary

It is anticipated that the location services now being implemented, particularly within the USA will enable the emergency call centres to provide a greatly improved services. With many millions of emergency calls being made each year from cell phones, this new technique will greatly assist in saving lives and providing swift support to exactly the correct location when it is needed.

By Ian Poole

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assisted gps - перевод - Английский-Русский Словарь

en In addition to real-time location and guide assisted GPS already offers unlimited opportunities for advertisers to target a local real need that goes much further than the search or that the ancient concept of yellow pages.

Common crawlru Кроме того в реальном времени и месте руководства Assisted GPS уже предлагает неограниченные возможности для рекламодателей целевую местных реальной необходимости, что идет гораздо дальше, чем поиск или что древняя концепция Yellow Pages.

en Support for high-speed HSDPA protocol further extends the functionality of Apple iPhone 3G. GPS-module of the phone uses A-GPS (Assisted GPS).

Common crawlru Основное отличие от других моделей заключается в наличии QWERTY-клавиатуры и большого (2.36") экрана.

en Personal digital assistants and GPS were also successfully used in the Brazilian agricultural census.

UN-2ru Персональные цифровые секретари и ГСОК также успешно использовались при проведении сельскохозяйственной переписи в Бразилии.

en After laboratory results are ready, GP assistant informs you by phone call and you schedule an appointment for extended consultation to discuss your treatment plan if needed.

Common crawlru После получения результатов обследования ассистент врача общей практики позвонит Вам и согласует дату расширенной консультации для обсуждения результатов и составления плана лечения, если это необходимо.

en The IACD was abolished and replaced by a new department whose latest initiatives involve, apart from the e-GP, assistance to national authorities with implementing legislative measures for the protection and development of SMEs through inter alia promoting their participation in public procurement by setting margins of preferences and set aside programs

MultiUnru МАСР было распущено и уступило место новому ведомству, чьи последние инициативы кроме ЭПЗ охватывают содействие национальным органам в осуществлении законодательных мер по защите и развитию МСП, в частности, путем содействия их участию в публичных закупках с помощью установления льготных преференций и самостоятельных программ

en GP assistant will make a remind call about check up.

Common crawlru Накануне прохождения обследования, ассистент врача общей практики позвонит Вам и напомнит дату и условия прохождения обследования.

en The IACD was abolished and replaced by a new department whose latest initiatives involve, apart from the e-GP, assistance to national authorities with implementing legislative measures for the protection and development of SMEs through inter alia promoting their participation in public procurement by setting margins of preferences and set aside programs.

UN-2ru МАСР было распущено и уступило место новому ведомству, чьи последние инициативы кроме ЭПЗ охватывают содействие национальным органам в осуществлении законодательных мер по защите и развитию МСП, в частности, путем содействия их участию в публичных закупках с помощью установления льготных преференций и самостоятельных программ.

en Her assistant tracked the GPS on her car.

opensubtitles2017ru Ее помощник отследил навигатор в ее машине.

en Client Service Manager will schedule your check up through GP assistant.

Common crawlru Менеджер Отдела по работе с клиентами проводит Вас к ассистенту Врача общей практики. Ассистент врача согласует с Вами дату прохождения обследования.

en Field GPS campaigns will assist in linking individual networks to the regional datum

MultiUnru Кампании GPS на местах будут содействовать привязке индивидуальных сетей к региональным исходным данным

en This procedure allowed rural establishments (farms, schools, etc.) to be georeferenced, as personal digital assistant devices were equipped with GPS.

UN-2ru Эта процедура позволила обеспечить географическую привязку сельских объектов (ферм, школ и т.д.), поскольку персональные электронные помощники были оснащены системой определения географических координат.

en GPS and computer assisted personal interviews were successfully used in conducting an agricultural census in Mozambique, with the preliminary results having been made available in fewer than six months.

UN-2ru при проведении сельскохозяйственной переписи в Мозамбике успешно использовались ГСОК и компьютеризированные персональные собеседования, при этом предварительные результаты переписи были готовы через менее чем шесть месяцев.

en Assistance was required by many countries with new technologies for scanning, GPS/GIS, online mapping tools, using personal digital assistants, hand-held mobile technology, using phones for monitoring and control, and e‐census.

UN-2ru Многие страны нуждаются в помощи по вопросам новых технологий сканирования, GPS/ГИС, онлайновых инструментов картирования, использования персональных цифровых компьютеров, применения портативных устройств мобильной связи и использования телефонов для мониторинга и контроля, а также системы электронной переписи.

en Denmark assisted the Institute in establishing the basic GPS network starting in 1992.

UN-2ru С 1992 года Дания помогает Институту в создании базовой сети GPS.

en Denmark assisted the Institute in establishing the basic GPS network starting in

MultiUnru С # года Дания помогает Институту в создании базовой сети GPS

en GPS and GIS systems are greatly assisting in survey and post clearance documentation.

UN-2ru Использование систем GPS и GIS оказывает немалую помощь в подготовке документации обследований и документации после проведения операций по расчистке.

en electronic driving assistance (ITS) and radio and telematic information to drivers (GPS, UMTS

MultiUnru электронной поддержки процесса управления транспортным средством (ИТС) и передачи радио- и телематической информации водителям (GPS, UMTS

en Automatic driving system consists of GPS receiver, direction indicator unit and steering assistance device. The system is presumed to be optionally installed on grain combines VECTOR, ACROS and TORUM.

Common crawlru В этом году аномально жаркое лето поставило под угрозу труд сотен российских аграриев: ожидалось, что по сравнению с прошлым гордом урожайность понизится на 20-25%.

en Grain combine with autopilot may work on the field on a desired route with minimal operator's involvement. Automatic driving system consists of GPS receiver, direction indicator unit and steering assistance device.

Common crawlru В рамках выставки «Золотая осень» подведены итоги конкурса на лучшую сельскохозяйственную машину 2009 года, проведенного по инициативе Минсельхоза РФ.

en The competence of GPs includes knowledge of the principles of family planning, psychology and assistance during menopause, as well as skills to control the use of contraceptives.

UN-2ru Квалификация СВ подразумевает знание основ планирования семьи, психологии и оказания помощи в период менопаузы, а также навыки контроля за использованием контрацептивов.

en The competence of GPs includes knowledge of the principles of family planning, psychology and assistance during menopause, as well as skills to control the use of contraceptives

MultiUnru Квалификация СВ подразумевает знание основ планирования семьи, психологии и оказания помощи в период менопаузы, а также навыки контроля за использованием контрацептивов

en Belarus reported that its formal request for assistance had been for a limited number of mine detectors, radios and global positioning systems (GPS) equipment.

UN-2ru Беларусь сообщила, что ее официальный запрос о помощи касался ограниченного числа миноискателей, радиостанций и приборов Глобальной системы определения местоположения (GPS).

en Reception is staffed by three social workers, two doctors (a GP and a psycho-neurologist) and a member of staff who writes letters of assistance.

Common crawlru В приеме участвуют три социальных работника, два врача - терапевт и психоневролог, сотрудник, составляющий "охранные грамоты".

en The main achievement was the installation, extensive testing and utilization of a multibeam echosounder with a combined GPS/inertial system for positioning and attitude, with the survey data being transferred to the computer-assisted cartography system CARIS.

UN-2ru Главным достижением были установка, тщательные испытания и ввод в эксплуатацию многолучевого эхолота с комбинированной ГСОК/инерциальной системой для определения координат и угловой ориентации с переводом данных в компьютерную картографическую систему КАРИС.

ru.glosbe.com

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Assisted GPS explained

Assisted GPS (abbreviated generally as A-GPS and less commonly as aGPS) is a system that often significantly improves the startup performance—i.e., time-to-first-fix (TTFF)—of a GPS satellite-based positioning system. A-GPS is extensively used with GPS-capable cellular phones, as its development was accelerated by the U.S. FCC's 911 requirement to make cell phone location data available to emergency call dispatchers.[1]

Description

Standalone/self-ruling GPS devices depend solely on information from satellites. A-GPS augments that by using cell tower data to enhance quality and precision when in poor satellite signal conditions. In exceptionally poor signal conditions, for example in urban areas, satellite signals may exhibit multipath propagation where signals skip off structures, or are weakened by meteorological conditions or tree canopy. Some standalone GPS navigators used in poor conditions can't fix a position because of satellite signal fracture and must wait for better satellite reception. A GPS unit may need as long as 12.5 minutes (the time needed to download the GPS almanac and ephemerides) to resolve the problem and be able to provide a correct location.[2]

An assisted GPS system can address these problems by using external data. Utilizing this system can come at a cost to the user. For billing purposes, network providers often count this as a data access, which can cost money, depending on the plan.

To be precise, A-GPS features depend mostly on an internet network or connection to an ISP (or CNP, in the case of CP/mobile-phone device linked to a cellular network provider data service). A mobile (cell phone, smart phone) device with just an L1 front-end radio receiver and no GPS acquisition, tracking, and positioning engine only works when it has an internet connection to an ISP/CNP, where the position fix is calculated offboard the device itself. It doesn't work in areas with no coverage or internet link (or nearby BTS towers, in the case on CNP service coverage area). Without one of those resources, it can't connect to the A-GPS servers usually provided by CNPs. On the other hand, a mobile device with a GPS chipset requires no data connection to capture and process GPS data into a position solution, since it receives data directly from the GPS satellites and is able to calculate a position fix itself. However, the availability of a data connection can provide assistance to improve the performance of the GPS chip on the mobile device.

Assistance falls into two categories:

  1. Mobile Station Based (MSB): Information used to acquire satellites more quickly.
    • It can supply orbital data or almanac for the GPS satellites to the GPS receiver, enabling the GPS receiver to lock to the satellites more rapidly in some cases.
    • The network can provide precise time.
  2. Mobile Station Assisted (MSA): Calculation of position by the server using information from the GPS receiver.
    • The device captures a snapshot of the GPS signal, with approximate time, for the server to later process into a position.
    • The assistance server has a good satellite signal and plentiful computation power, so it can compare fragmentary signals relayed to it.
    • Accurate, surveyed coordinates for the cell site towers allow better knowledge of local ionospheric conditions and other conditions affecting the GPS signal than the GPS receiver alone, enabling more precise calculation of position.

As an additional benefit, in mobile station assisted implementations, the amount of processing and software required for a GPS receiver can be reduced by offloading most of the work onto the assistance server.

A typical A-GPS-enabled receiver uses a data connection (Internet or other) to contact the assistance server for aGPS information. If it also has functioning autonomous GPS, it may use standalone GPS, which is sometimes slower on time to first fix, but does not depend on the network, and therefore can work beyond network range and without incurring data-usage fees.[3] Some A-GPS devices do not have the option of falling back to standalone or autonomous GPS.

Many mobile phones combine A-GPS and other location services, including Wi-Fi Positioning System and cell-site multilateration and sometimes a hybrid positioning system.[4]

High-Sensitivity GPS is an allied technology that addresses some of these issues in a way that does not require additional infrastructure. However, unlike some forms of A-GPS, high-sensitivity GPS cannot provide a fix instantaneously when the GPS receiver has been off for some time.

Basic concepts

Standalone GPS provides first position in approximately 30–40 seconds. A standalone GPS needs orbital information of the satellites to calculate the current position. The data rate of the satellite signal is only 50 bit/s, so downloading orbital information like ephemerides and the almanac directly from satellites typically takes a long time, and if the satellite signals are lost during the acquisition of this information, it is discarded and the standalone system has to start from scratch. In A-GPS, the network operator deploys an A-GPS server, a cache server for GPS data. These A-GPS servers download the orbital information from the satellite and store it in the database. An A-GPS-capable device can connect to these servers and download this information using mobile-network radio bearers such as GSM, CDMA, WCDMA, LTE or even using other radio bearers such as Wi-Fi. Usually the data rate of these bearers is high, hence downloading orbital information takes less time.

Modes of operation

A-GPS has two modes of operation:

Mobile Station Assisted (MSA): In MSA mode A-GPS operation, the A-GPS capable device receives acquisition assistance, reference time and other optional assistance data from a mobile service provider. The mobile service provider continuously logs GPS information (mainly the almanac) from the GPS satellites using an A-GPS server in its system. With the help of the above data (the data received from the mobile device and the data already present in A-GPS server) the A-GPS server calculates the position and sends it back to the A-GPS device.
  • Mobile Station Based (MSB): In MSB mode A-GPS operation, the A-GPS device receives ephemeris, reference location, reference time and other optional assistance data from the A-GPS server. With the help of the above data, the A-GPS device receives signals from the visible satellites and calculates the position.[5]

    Standards

    A-GPS protocols are part of Positioning Protocol defined by two different standardization bodies, 3GPP and Open Mobile Alliance (OMA).

    Control Plane Protocol: It is defined by 3GPP for various generations of mobile phone system. These protocols are defined for Circuit Switched Networks. Following positioning protocol has been defined.
    • RRLP – 3GPP defined RRLP or Radio resource location protocol to support positioning protocol on GSM networks.
    • TIA 801 – CDMA2000 family defined this protocol for CDMA 2000 networks.
    • RRC position protocol – 3GPP defined this protocol as part of the RRC standard for UMTS network.
    • LPP – 3GPP defined LPP or LTE positioning protocol for LTE Networks.
    User Plane Protocol:

    It is defined by OMA to support positioning protocols in Packet Switched Networks. Two generations of User plane Protocol have evolved.

    See also

    External links

    GPS assisted with Indoor Location Technologies

    Notes and References

    1. Web site: Assisted GPS: A Low-Infrastructure Approach. GPS World. March 1, 2002. 11 June 2008.
    2. Web site: NavCen GPS User. 3.5.3 Almanac Collection. PDF. Navcen.uscvg.gov. 2017-04-02.
    3. Web site: Low. Aloysius. Phones. CNET. 2017-04-02.
    4. Web site: iPhone Secrets and iPad Secrets and iPod Touch Secrets. Edepot.com. 2010-09-30. 2017-04-02.
    5. Web site: GPS vs. aGPS: A Quick Tutorial | Windows Central. Wpcentral.com. 2009-01-03. 2017-04-02.
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