Is it the gospel or invasion of privacy? Advanced positioning technology for accurate position determination

Location, location, or location! It is a decisive factor, whether it involves real estate or simply indicates where you are standing now. Determining location by technology is not a new concept. For many years, a variety of receivers (or radiolocations) with directional antennas and triangulation have been used to track any object that emits radio waves. And since the Second World War, radar has been indispensable in military operations. At the moment, things are reversed. What happens when your technology can determine your own location? Some of these electronic methods have existed for many years, such as remote navigation systems for ship positioning (Loran, Roland Systems). And the Global Positioning System (GPS) of 24 satellites that have also been in operation for some time. First, GPS was created for military purposes. However, there are currently hundreds of civilian devices and they are becoming the core of many new commercial positioning technology systems.

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GPS 101

In fact, GPS is a huge positioning technology. Its 24 satellites operate in an orbital plane at six dips and 55 degrees from the equator. The satellite is located at 20,000 km, or about 11,000 miles, with a period of nearly 12 hours. Each satellite broadcast signal is in the microwave L-band (1.57542 and 1.2276 GHz), which contains code and time information, all of which can be obtained by receivers located anywhere on the earth.

At any time, four to six airborne satellites allow the receiver to select three to four signals for calculation, which in turn produces latitude, longitude, altitude, and velocity information. Because the signal is synchronized to the atomic clock loaded on the satellite, they provide ultra-precise time information.

The level of positioning accuracy varies with the exact position and receiver, but is typically in the range of 10 to 50 meters. The GPS system was maintained through the 2nd Space Operations Squadron of the US Air Force's 50th Combat Battalion at Schriever Air Force Base (AFB) in Colorado. Military GPS is used for navigation, search and rescue, as well as precise targeting of bombs and missiles. Civil use includes navigation, measurement, and mobile phone positioning.

The US Coast Guard's NAVCEN is responsible for the Coast Guard Offshore Differential GPS (DGPS) service, which consists of two control centers and more than 60 remote broadcast sites. It broadcasts a correction signal at the maritime radio beacon frequency to improve the accuracy of the GPS derived position. It claims to have an accuracy of 10m in all confirmed coverage. However, the positioning error of the DGPS position is usually 1 to 3 meters, which greatly enhances the port entrance and inbound navigation. In addition, the use of DGPS requires a dedicated receiver.

A new version of GPS is assisted or assisted by GPS (A-GPS). Initiated by Qualcomm, it improves the ability of GPS receivers to generate high-precision positioning information, even when it is not available in satellites. In general, most GPS receivers cannot acquire indoor signals or acquire signals in the city's "canyon."

A-GPS is used in many new phones with the features required by the Enhanced 911 Act. A dedicated fixed GPS receiver near the local handset carrier requires satellite data and sends it over the network to a mobile phone that can use GPS. This ultimately speeds up capture and calculation time. At first, these complex GPS receivers cost thousands of dollars each. Currently, you can purchase a basic satellite receiver for less than $200. Moreover, semiconductor manufacturers can now offer on-chip GPS receivers for less than $10, making it possible to embed GPS functionality into other projects. This has enabled the use of GPS to be extended to a wide range of location services.

Dozens of different handheld GPS receivers provide latitude and longitude information, and their number is currently growing rapidly. But who will carry a map with coordinates? Therefore, receiver manufacturers provide maps that rely on satellite data. The receiver's LCD screen displays a map of the current area of ​​your location.

These receivers from Garmin, TomTom, and other manufacturers cost more than $1,000, but they are absolutely necessary if you have to know where you are going. Some receivers allow you to draw a path to your destination, and the receiver provides directions step by step. This feature is currently being installed in the latest high-end luxury cars.

Some mobile phone companies also offer GPS map location services. Verizon's VZ navigation service is priced at $10/month. Use your phone as a GPS receiver and display your route on the map of the screen. Sprint Nextel offers similar services at essentially the same price. All operators offer high-end handsets with GPS receiver functionality as required by the Federal Communications Commission Enhanced 911 Act. You can also install navigation software like ALK CoPilot LIVE, Destinator SP and TomTom Navigator 5 on your own smartphone.

Some operators even offer similar services to help parents locate their children. First, the children need to have a GPS-enabled cdma2000 phone from Sprint Nextel or Verizon. Sprint's Family Locator service costs about $10/month for more than four phones. Parents use their own mobile phone to customize the service, which uses the address and ground sign near the child's mobile phone to report the child's location. It can also send text messages to the phone to indicate the location of the tracked phone, a similar unrestricted service offered by Nextel each month. Disney's mobile home locator service also operates in a similar manner.

The driving force of positioning technology

In 1996, the FCC required all mobile phones to include technology that could locate their location by dialing the National Emergency Service 911. The bill is called Enhanced 911 (E911), which became necessary after the phone dialed the 911 number. The 911 Public Safety Answering Point (PSAP) makes it easy to locate alarms from fixed telephones whose addresses are automatically located. Of course, an alarm call may come from anywhere.

The FCC is preparing to correct this problem in 2001. However, due to the reasons of operators and mobile phone manufacturers, the deadline was extended to December 31, 2005. However, despite this, not all of them met the requirements, which led many operators to give up and be fined.

Operators may have two solutions, either through a mobile phone or a network. The mobile phone solution uses an internal GPS receiver to return location information to the network, which provides the information to the PSAP. For example, Verizon and Sprint Nextel, operators offer cdma2000 technology, which uses Qualcomm chips to implement this approach. These cores also contain A-GPS features. The biggest problem is convincing customers to give up their old-fashioned phones and buy new phones with new technology.

Cingular and T-Mobile chose their GSM network as their network solution. They employ a system called uplink time difference of arrival (UTDOA). Developed by TruePosition, the system uses a dedicated receiver called a Position Measurement Unit (LMU) on each cell phone base station and also includes an existing antenna.

The U-TDOA system uses a method similar to radio direction finding triangulation (see figure). It locates the location of the handset by measuring the difference in signal arrival times at different receiver base stations. The LMU detects the signal time, which is a function of the distance of the transmission path between the handset and each LMU. Accurate time information must be used to achieve the desired accuracy.

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Most LMUs combine the high precision clocks obtained by the GPS receiver at each cell phone base station. With the DSP, the system matches the LMU's signal and determines the difference in reception time. The measurements of the three LMUs allow the system to calculate the latitude and accuracy of the handset with an accuracy of more than 50 m. The information is then submitted to the PSAP.

One of the benefits of the U-TDOA system is that it does not require any hand-held add-ons. It can also be used for GSM phones, as older analog and TDMA phones are the same as newer WCDMA 3G phones. The system currently has more than 50,000 mobile base stations nationwide, but more than 44,000 will be installed next year.

The FCC's goal is to enable operators to locate 67% of the alarm calls made by 911 phones within 50m using a handheld solution and locate 95% of all alarm calls within 150m. In the network solution, the operator should locate 67% of the 911 alarm calls within 100m, and within 95m is 95% of all alarm calls.

Other wireless technologies

If you use mobile technology to locate your phone or other device, you can use other wireless technologies to achieve it very well. For example, radio frequency identification (RFID) is rapidly replacing barcodes. Most RFID tags are passive and do not have their own power supply. However, when the RFID reader or interrogator unit sends an interrogation signal, the tag uses the signal to provide power and transmits a unique electronic product code (EPC) stored in its memory to the reader. For most tags, the reading distance is very short, from just a few inches to hundreds of feet of new UHF tags. Active RFID tags use internal batteries to provide power to send their code and location to readers hundreds of feet away.

The high cost of tags hinders the development of RFID. But at present, the price of passive tags is declining, and at the same time, the reading distance is constantly increasing. Active tags are more expensive, but they are still worthy of adoption on larger and more expensive projects. RFID is primarily used for cargo tracking, asset management, and shipping and transportation applications. It tracks animals and people, automatically charges them, and charges the added gasoline on the pumps that they are allowed to use.

Due to its short reading distance, RFID is a difficult positioning technology. With a network of readers in an ideal location, a triangulation scheme can be used to achieve reasonable accuracy in determining the person or target within the coverage area. Active RFID tags improve positioning accuracy, allowing the system to cover a wider range due to its longer reading distance and fewer readers.

This technology with Wi-Fi capability is more effective. It can also be used to track laptops or other devices when designing 802.11 wireless local area network (WLAN) standards for wireless access to the LAN and connection to the Internet via hotspots. Organizations with many Wi-Fi entry points can use it to find a particular laptop, PC, PDA or cell phone. If a Wi-Fi device appears in any hotspot, it can be identified.

There are already tens of thousands of hotspots connected at airports, hotels and other public places, and the location has become extremely precise. Since many municipal Wi-Fi mesh networks have been installed in many cities across the country, the possibility of location has been further improved. G2 Microsystems has developed a chip that combines a low-power 802.11b transceiver with a new 900MHz RFID circuit with 125kHz and a new active tag for positioning applications.

Positioning technology can take many new forms. The system from eTelemetry consists of hardware and software that identifies the Switch Port, department, physical address, and the number of phones assigned to each IP address. It can use network management feedback to locate network failures, determine who will use the maximum bandwidth, and handle other monitoring applications.

In fact, the development of positioning technology has produced a new industry called Real Time Location System (RTLS). It uses RFID and Wi-Fi or other technologies to create wireless systems that can be used to locate small electronic devices on people or objects at any time. By employing an RFID reader array and Wi-Fi access points, it is possible to cover a defined area by location range.

Possible locations include hospitals, theme parks, parking lots, factories and warehouses, as well as post offices or other shipping facilities. Research firm IDTechEx predicts that the industry will increase to $2.71 billion in 2016. The core of the technology includes not only wireless hardware, but also software that collects and clarifies the meaning of all tags and other data collected by the reader.

Location-based information service (LBS)

With such a large positioning system placed in place, operators have considered how they can get a commercial return on their mandatory investments. Mobile operators have great interest in ways to compensate for the huge investment required by E911. But what about these LBS? The “gatekeeper” service will be identified in restaurants, malls or wherever. It allows consumers to find service facilities at any time. It can even broadcast advertisements when you go through a restaurant or store, but this can cause problems. The LBS industry has not yet been fully established, but once the E911 service is nearly fully implemented, it will begin to act immediately.

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