BeiDou Satellite System. Development of the Chinese BeiDou satellite navigation system
20/12 /2013
Priorities 2014: serve society, benefit humanity - the system is developing!
Chengchi RenRan),
CEO Chinese
Satellite Navigation Bureau
TranslationarticlesDirections 2014: Serve the World, Benefit Mankind - A System Matures (GPS World, 1 December 2013) completedCompany « PRIN» V 2013 year.
Adhering to the principles of independence, openness, interoperability, and gradual development, China is progressively deploying its own BeiDou global navigation satellite system (BDS), following the planned three-stage development strategy.
By 2000, the BeiDou demonstration satellite navigation system of the first phase of development was created. By December 2012, the regional navigation satellite system was deployed: five geostationary geostationary orbit (GEO), five inclined geosynchronous orbit (IGSO) satellites, and four medium earth orbit (MEO) satellites were launched to form an operational constellation, and the provision of navigation services to Asia-Pacific officially began. Pacific region.
Chengchi RenRan is the Director General of the China Satellite Navigation Bureau and the Spokesperson of the Bei Navigation Satellite System.Dou. He graduated from Tsinghua University with a master's degree in industrial engineering and was previously director of the General Department of Technology at the China Satellite Navigation Project Center.
The contribution of BDS to users in China and around the world is widely recognized. The system will be fully functional and provide services to users around the world presumably by 2020.
Deploymentsystems
Taking this further, new satellites will be launched in 2014 to complement the existing constellation, while regional operational capabilities will be upgraded and expanded to international levels. In total, about 40 satellites should be launched by 2020.
Currentsystem performance
Determination accuracies from single-frequency observations in plan, height, and space were achieved at levels of less than 10 meters, 10 meters, and 14 meters, respectively. Time synchronization accuracy is less than 50 nanoseconds. The speed determination accuracy is less than 0.2 meters per second. The accuracy of the differential carrier phase solution is about 2-3 centimeters. Over the past year, the BDS system has been continuously improved and expanded, and its performance in some regions has significantly exceeded previous indicators.
Assistance in application
The use of BDS plays an important role in China, especially in the field of science and technology promotion. Chinese scientists and engineers have consciously and enthusiastically embraced the emergence of an independent navigation satellite system, and have made great strides in the research and development of navigation satellite technology, as well as new achievements in the production of navigation chips, antennas, terminals and integrated services.
In 2012, the total output of China's satellite navigation and location services industry reached 81 billion yuan (equivalent to $13.2 billion), accounting for 8 percent of the industry worldwide. At the end of 2012, the number of BDS devices for civilian use was 230,000 units, and the total output value of the BDS-related industry was close to 4 billion yuan ($652 million), accounting for about 5 percent of the total national product.
China's policy to expand the use of satellite navigation is under development. The mid- and long-term development plans for the national satellite navigation industry were issued. Satellite navigation has become one of the emerging industries of strategic importance. BDS is moving China's satellite navigation and location-related industry into a new era.
Distributionvisiblein orbitsatellitesBeiDou.
The international cooperation
China upholds and adheres to the concept of "BeiDou for China and for the world", advocating the compatibility and complementarity of all navigation satellite systems, and strives to promote the global application of navigation satellite systems. To provide users with more reliable and reliable satellite navigation services, BDS has joined the international GNSS monitoring and quality assessment community. Using tracking stations around the world, international exchange of observations, and collaborative assessment studies, BDS strives to offer reliable monitoring, assessment and data to users.
To more quickly achieve the intended BDS coverage area, campaigns have been initiated to implement, demonstrate and test the BeiDou system. "BeiDou Asia Pacific Tour" and "BeiDou ASEAN Tour" were launched to accelerate the application of satellite navigation systems in many countries. To popularize satellite navigation technology, particularly to increase its acceptance and application in developing countries, BDS provided academic education, short-term training and topical lectures with the support of the International GNSS Center for Exchange and Training.
China also holds an annual satellite navigation conference, actively participates in international exchange events in the field of satellite navigation, and promotes scientific exchange, high-level forums and knowledge popularization.
A look into the future
BDS is actively interested in:
- establishing navigation satellite differential correction systems in the Asia-Pacific region and around the world, developing more efficient services to provide real-time decimeter-level accuracy and post-processing centimeter-level accuracy;
- creation of certification and testing centers for the quality of satellite navigation products;
- accelerating the development of rules and intellectual property rights;
- joining international organizations such as the International Civil Aviation Organization (ICAO), the International Maritime Organization (IMO), the consortium developing specifications for mobile telephony (3GPP);
- strengthening compatibility and interoperability with other navigation satellite systems;
- promoting the application of BDS/GNSS in transportation, energy, government, finance, telecommunications, disaster risk reduction, relief, etc., to realize the goals of BDS to serve peace and humanity.
BDS will take full advantage of the unique advantages of navigation, communications, and differential correction services to enhance its own Short Message Service (SMS), as well as provide operational positioning and timing capabilities. BDS effectively integrates satellite and terrestrial differential correction systems and insists on introducing compatibility and complementarity between different GNSS. This will ensure its seamless integration with mobile communications, positioning services, the Internet, high quality, reliable and efficient operation for environmental and social development, public safety, and individual users.
Modern Trimble GNSS receivers support the reception of BeiDou system satellite signals with the ability to post-process the received data and operate in RTK mode: , - as standard, R8s, R9s, and - optional. All PrinCe receivers support Beidou system satellites by default.
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In the description of the characteristics of navigation systems such as GPS and GLONASS used in mobile devices, one can recently come across one more. We will tell you what Beidou is and what it is used for in a smartphone.
What is Beidou
As mentioned above, Beidou is a Chinese satellite navigation system, an analogue of the American GPS and, as well as the European Galileo project, which has not yet reached the stage of active commercial use.It received its name in honor of the Chinese version of the name of the constellation Ursa Major.
The system consists of a satellite constellation and a network of ground stations, most of which are located in China. However, recently there has been intensive expansion: land bases have appeared in the following countries and regions:
- Russia.
- Pakistan.
- Singapore.
- Australia.
- Africa.
- Europe.
However, so far Beidou, in terms of the size of its coverage, cannot be considered a global system and is classified as regional, just like, for example, the Indian IRNSS.
What principle does Beidou work on?
As in any other modern navigation system, the location of the device is determined by measuring the speed of transmission of the radio signal to it from a transmitter located on a satellite or ground station.
Next, trivial geometry comes into play: since the speed of propagation of electromagnetic waves in the atmosphere is constant, having the coordinates of at least three sources, the system determines the point where the device is located with an error of less than 1 meter.
What devices support this system
First of all, these are gadgets from Chinese manufacturers intended for the Chinese market. For example, support for using Beidou is available in such an inexpensive (about 5 thousand rubles) smartphone as.At the same time, devices intended for other markets may not have this system. For example, for devices intended for sale to Russians, GLONASS may be installed instead of Beidou.
In addition, many other manufacturers in Southeast Asia equip their devices with this system. It is available in smartphones from brands such as, although not in every model.
But such well-known top gadgets as Google Pixel or iPhone X do not have the Beidou module, while they are capable of working with GLONASS.
How to Determine If Your Smartphone Supports Beidou
To do this, you can use the AndroiTS GPS Test application, which can be downloaded from. Among other tabs, it contains a list of satellites with which the smartphone can interact.
The nationality of each of them is indicated by the flag of the corresponding country. If there are red Chinese flags on the list, then Beidou is also on it.
However, the owner does not need to take any action to use this system. Chinese satellites will be used to improve the accuracy of position determination on a par with GLONASS and GPS satellites when accessing the navigation of corresponding applications.
As the creators of Beidou assure, by 2020 it should become a full-fledged global navigation system, in no way inferior to its American and Russian competitors. Whether this will actually happen, the future will show: we’ll wait and see.
When you're looking at a new smartphone to buy, you look not only at its appearance, but also at its characteristics. In the characteristics you can often see the following combination: GPS/GLONASS/BeiDou. If everything is clear with GPS and GLONASS, then what is BeiDou?
BeiDou (pronounced Beidou) is a Chinese satellite navigation system. It was launched into commercial operation in 2012, and will reach full capacity around 2020.
In fact, it is an analogue of GPS and GLONASS - these two systems are standardly supported by most new smartphones. Recently, the BeiDou navigation system was added to them, so you can often see in the “Satellite navigation” characteristics column support for three satellite navigation systems - GPS, GLONASS and BeiDou.
Many smartphones have already received BeiDou support, but not all yet. This is primarily done by Chinese companies, but there are also companies from other countries, such as Samsung, which has enabled BeiDou support on many of its devices.
What is the benefit of all this to the user, you ask? In fact, the user of the device wins. Look, each navigation system has its pros and cons, but be that as it may, together they allow you to more accurately position the device on satellites. And don’t forget that when the Internet is turned on, positioning also occurs via it. The more sources, the more accurately the location of the user with the device is indicated. Of course, there is nothing bad here, all pluses.
In the future, BeiDou will probably be supported by almost all smartphones, as was the case with GPS or GLONASS.
Lecture on the anatomy of mobile devicesV. Navigation (GPS, GLONASS, etc.) in smartphones and tablets. Sources of errors. Testing methods.
Until recently, it was possible to buy devices called “Navigators” in retail chains. The main function of these devices fully corresponded to their name, and they usually performed it well.
At that time, practically the only normally functioning navigation system in the world was the American GPS (Global Positioning System), and it was enough for all needs. Actually, the words “navigation” (navigator) and GPS were synonymous at that time.
Everything changed when manufacturers of PDAs (handheld computers), and then smartphones and tablets, began to build navigation support into their devices. Physically, it was implemented in the form of built-in receivers of navigation signals. Sometimes navigation support could be found even in push-button phones.
From that moment on, everything changed. Navigators, as separate devices, have almost disappeared from both production and sale. Consumers have switched en masse to using smartphones and tablets as navigators.
In the meantime, two more navigation systems were successfully put into operation - the Russian GLONASS and the Chinese Beidou (Beidou, BDS).
But this does not mean that the quality of navigation has improved. The navigation function in these devices (smartphones and tablets) has no longer become the main one, but one of many.
As a result, many users began to notice that not all smartphones are “equally useful” for navigation purposes.
This is where we come to the problem of identifying the sources of errors in navigation, including the question of the role of dishonesty of device manufacturers in this matter. Sad but true.
But before blaming manufacturers for all their sins, let’s first look at the sources of errors in navigation. For producers, as we will find out later, are not to blame for all sins, but only for half. :)
Navigation errors can be divided into two main classes: caused by reasons external to the navigation device, and internal.
Let's start with external reasons. They arise mainly due to the unevenness of the atmosphere and the natural technical error of measuring instruments.
Their approximate contributions are:
Signal refraction in the ionosphere ± 5 meters;
- Satellite orbit fluctuations ± 2.5 meters;
- Satellite clock error ± 2 meters;
- Tropospheric unevenness ± 0.5 meters;
- The influence of reflections from objects± 1 meter;
- Measurement errors in the receiver ± 1 meter.
These errors have a random sign and direction, so the final error is calculated in accordance with probability theory as the root of the sum of squares and is 6.12 meters. This does not mean that the error will always be this way. It depends on the number of visible satellites, their relative position, and most of all, on the level of reflections from surrounding objects and the influence of obstacles on the weakening of satellite signals. As a result, the error may be either higher or lower than the given “averaged” value.
Signals from satellites may weaken, for example, in the following cases:
- when indoors;
- when located between closely spaced high objects (between high-rise buildings, in a narrow mountain gorge, etc.);
- while in the forest. Experience shows that dense, tall forest can make navigation significantly more difficult.
These problems are due to the fact that high-frequency radio signals travel like light - that is, only within a line of sight.
Sometimes navigation, albeit with errors, can also work on signals reflected from obstacles; but when repeatedly reflected, they become so weak that navigation stops working with them.
Now let's move on to the "internal" causes of errors in navigation; those. which are created by the smartphone or tablet itself.
Actually, there are only two problems here. Firstly, poor sensitivity of the navigation receiver (or problems with the antenna); secondly, the “crooked” software of a smartphone or tablet.
Before looking at specific examples, let's talk about ways to check the quality of navigation.
Navigation testing methods.
1. Testing navigation in “static” mode (with the smartphone/tablet in a stationary position).
This check allows you to determine the following parameters:
- speed of initial determination of coordinates during a “cold start” (measured by the clock);
- a list of navigation systems that this smartphone/tablet works with (GPS, GLONASS, etc.);
- estimated accuracy of coordinate determination;
- speed of determining coordinates during a “hot start”.
These parameters can be determined using both regular navigation programs and special test programs (which is more convenient).
The rules for static testing are very simple: testing must be done in open space(wide street, square, field, etc.) and when the Internet is turned off. If the last requirement is violated, the “cold start” time can be significantly accelerated due to direct downloading of satellite orbits from the Internet (A-GPS, assisted GPS) instead of determining them from signals from the satellites themselves; but it will no longer be “fair”, since this will no longer be the pure work of the navigation system itself.
Let's look at an example of how the AndroiTS navigation testing program works (there are analogues):
(click to enlarge)
The picture just presented shows that the smartphone works with three navigation systems: American GPS, Russian GLONASS and Chinese Beidou (BDS).
At the bottom of the screenshot you can see the successfully determined coordinates of the current location. The value of one degree in latitude is approximately 100 km; accordingly, the price of a unit of the lowest rank is 10 cm.
The value of one degree in longitude is different for different geographical locations. At the equator it is also about 100 km, and near the poles it decreases to 0 (at the poles the meridians come closer together).
To the right of the column indicating the nationality of the satellites is a column with satellite numbers. These numbers are strictly attached to them and do not change.
Next come columns with colored bars. The size of the bars indicates the signal level, and the color indicates whether or not they are being used by the navigation system. Unused satellites are indicated by gray bars. The color of those used depends on their signal level.
The next column is also the signal level from navigation satellites, but in numbers (“conventional units”).
Then there is a column with green checkmarks and red dashes - this is a repetition of information about whether the satellite is being used or not.
In the top line, the word "ON" indicates the status of the navigation state; in this case, this means that the determination of coordinates is allowed in the smartphone settings and they are determined. If the status is “WAIT”, then determination of coordinates is allowed, but the required number of satellites has not yet been found. The "OFF" status means that coordinate determination is prohibited in the smartphone settings.
Then, a circle with concentric circles and the number 5 indicates the estimated accuracy of determining the coordinates at the moment - 5 m. This value is calculated based on the number and “quality” of satellites used and assumes that the processing of data from satellites in a smartphone is done without errors; but, as we will see later, this is not always the case.
As the satellites move, all this data should change, but the coordinates (in the bottom line) should change slightly.
Unfortunately, this application does not show the time spent on the initial determination of coordinates (“cold start”), and neither do other similar applications. This time must be “timed” manually. If the “cold start” time was less than a minute, then this is an excellent result; up to 5 minutes – good; up to 15 minutes – average; more than 15 minutes – bad.
To determine the “hot start” speed, just exit the testing program and log in again after a few minutes. As a rule, during the launch of the test program, it manages to determine the coordinates and immediately presents them to the user. If the delay in presenting coordinates during a “hot start” exceeds 10 seconds, then this is already suspiciously long.
The effect of quickly determining coordinates during a “hot start” is due to the fact that the navigation system remembers the last calculated satellite orbits and does not need to determine them again.
So, we’ve sorted out testing navigation in “static” mode.
Let's move on to the 2nd point of testing navigation - in motion.
The main purpose of navigation is to lead us to the right place while moving, and without testing while moving, the test would be incomplete.
In the process of movement, from a navigation point of view, there are three types of terrain: open terrain, urban areas and forest.
Open areas are ideal navigation conditions; there are no problems here (except for very “sucky” devices).
Urban development in most cases is characterized by the presence of a high level of reflections and a slight decrease in the signal level.
The forest “works” the other way around – a significant weakening of the signal and a low level of reflections.
First, let's look at a sample of an almost "ideal" track:
The picture shows two tracks: there/back (this will continue to be the case in almost all pictures). Such pictures allow you to make a reliable conclusion about the quality of navigation, since you can compare two almost identical tracks with each other and with the road. Everything is fine in this picture - the track vibrations are within the limits of natural error. In the upper part, the passage on different sides of the roundabout is adequately drawn. In some places, there is a noticeable discrepancy between the tracks, probably caused by signal reflections from the water surface and from the metal structures of the bridge over the river. And in some - an almost perfect coincidence.
Now let's look at several typical cases of "problem" tracks.
Let's look at the GPS track of a smartphone, which was affected by a decrease in signal level in a high forest:
The divergence of the tracks from each other and from the road is noticeable, but far from catastrophic. In this case, the accuracy of smartphone navigation decreased within the limits of “natural decline” for such conditions. Such a smartphone must be considered suitable for navigation purposes.
On the right side of the screenshot, the discrepancies between the tracks and the road are clearly visible. Such discrepancies in the conditions of such a “well-shaped” development are almost inevitable, and in this case they do not in any way indicate against the smartphone being tested.
Theoretically, the more navigation systems a smartphone (tablet) supports, the more satellites it uses for navigation and the smaller the error should be.
In practice, this is not always the case. Quite often, due to crooked software, a smartphone cannot correctly connect data from different systems and, as a result, abnormal errors occur. Let's look at a few examples.
Take, for example, this track:
The screenshot just shown shows a needle-shaped ejection, which could not be the result of any interference: the path passed through a low-rise building without dense forested plantings. This release is entirely on the conscience of the “crooked” software.
But these were still “flowers”. There are smartphones where abnormal navigation errors are no longer flowers, but berries:
When recording this track, anomalous errors in the “crooked” software were combined with weakening of the signals in the high forest. The result is a track from which it is simply impossible to guess that the path there and back was taken along the same path by a sober person. :)
And the thick bunch of lines at the top is the “path” of a motionless smartphone during a rest stop. :)
There is another type of anomalous error associated with a pause in the data flow coming from the navigation receiver to the computing part of the smartphone:
This picture shows that part of the path (about 300 m) passed in a straight line, and partly directly through the water. :)
In this case, the smartphone simply connected the points where the coordinate stream disappeared and appeared with a straight line. Their loss could be associated either with a decrease in the number of visible satellites below a critical number, or with “crooked” software and even hardware problems (although the latter is unlikely).
In the event of a complete loss of signals from satellites, navigation programs usually do not connect the points of loss and appearance with straight lines, but simply leave an “empty space” (this results in a gap in the track):
This picture shows a break in the track in the place where part of the path passed through an underground passage with a complete loss of visibility of all satellites.
After studying the causes and typical navigation errors, it’s time go to conclusions.
The best navigation, as you would expect, is found in smartphones and tablets of “high” brands. Problems in the form of anomalous errors have not yet been detected with them. And, of course, the more navigation systems a device supports, the better. True, support for the Chinese Beidou still makes sense when using the device in regions and countries located near the Middle Kingdom. The Chinese navigation system is not global, but “local” (for now). So support for GPS and GLONASS will be quite enough.
If a smartphone or tablet is not of very “renowned” origin, then there may or may not be problems with navigation. Before using it in combat, it is recommended to test it both statically and in motion in different environments, so that later it does not present any unpleasant surprise. In most cases, mobile devices with only GPS support cause fewer problems, although they are less accurate than multi-system ones.
Unfortunately, when choosing a smartphone (tablet) with good navigation, it is quite difficult to navigate through reviews of devices on the Internet. The overwhelming number of IT portals ignore checking navigation on the move and in difficult conditions. This check is done only on this portal () and literally on a couple of others.
Finally It must be said that not only smartphones and tablets, but also many other devices are now equipped with navigation aids. They are installed, for example, in cameras, video cameras, GPS trackers, car video recorders, smart watches, some specialized types of devices, and even in the electronic tax system for drivers of Russian heavy trucks "Platon".
Your Doctor.
20.01.2017
Beidou Navigation System or Beidou Satellite Navigation System (abbreviated as BD) is a Chinese satellite navigation system. As of October 26, 2012, it included 16 satellites located in geostationary orbit and provided the determination of geographic coordinates in China and neighboring territories. It is planned that the space segment of the Beidou navigation satellite system will consist of 5 satellites in GEO and 30 satellites in non-GEO orbits.
The system was launched into commercial operation on December 27, 2012 as a regional positioning system, with a satellite constellation of 16 satellites. It is planned that the system will reach full capacity by 2020. Chinese representatives also noted that issues regarding frequency ranges have yet to be resolved with the Russian, American and European parties, which also own satellite navigation constellations. In the meantime, the Chinese system operates on the B1 signal frequency, also designated by the European Union as E2, with a frequency of 1559.052-1591.788 MHz. The two sides have still not reached a final agreement on the compatibility of their future satellite navigation systems, despite ongoing negotiations since 2009 on the issue of overlaying the special signals of the Compass system with the special PRS signals of the Galileo system (L1 band, center frequency 1575.42 MHz).
Estimated future frequencies B2: 1166.22 - 1217.37 MHz, B3: 1250.618 - 1286.423 MHz.
The word “Beidou” (Chinese –k“l) translated means “Northern Dipper”, this is the Chinese name for the constellation Ursa Major. The name "Beidou" is used for both the "Beidou-1" system and the second generation "Beidou-2" system. The chief designer of both systems is Sun Jiadong.
The China National Space Administration plans to deploy the BeiDou navigation system in three stages.
- 1) 2000--2003: Beidou experimental system of three satellites.
- 2) by 2012: Regional system to cover the territory of China and surrounding areas.
- 3) by 2020: Global navigation system.
The first satellite, Beidou-1A, was launched on October 30, 2000. The second, Beidou-1B, was launched on December 20, 2000. The third satellite, Beidou-1C, was sent into orbit on May 25, 2003 as a backup satellite. The system was considered operational with the successful launch of the third satellite.
- On November 2, 2006, China announced that Beidou will offer open services with a location accuracy of 10 meters from 2008. BeiDou system frequency: 2491.75 MHz.
- On February 27, 2007, a fourth satellite within Beidou-1, sometimes called Beidou-D and sometimes called Beidou-2A, was also launched. It serves as a safety net. It was reported that the satellite had problems with its control system, but they were subsequently fixed.
In April 2007, the first satellite of the Beidou-2 constellation, named Compass-M1, was successfully launched into orbit. This satellite is a tuning satellite for Beidou-2 frequencies. The second satellite “Compass-G2” was launched on April 15, 2009. The third (“Compass-G1”) was launched into orbit by the LM-3C carrier on January 17, 2010. The fourth satellite was launched on June 2, 2010. The LM-3I carrier launched the fourth satellite from the satellite site in Xichang August 1, 2010.
- On January 15, 2010, the official website of the Beidou satellite navigation system was launched.
- On February 24, 2011, 6 operational satellites were deployed, 4 of them are visible in Moscow: COMPASS-G3, COMPASS-IGSO1, COMPASS-IGSO2 and COMPASS-M1.
- On December 27, 2011, Beidou was launched in test mode, covering the territory of China and adjacent areas.
- On December 27, 2012, the system was launched into commercial operation as a regional positioning system, with a satellite constellation of 16 satellites.
According to some sources, at the beginning of 2011, the State Council of the People's Republic of China reviewed the system architecture and made adjustments to the spacecraft launch plan. It was decided to complete the formation of an orbital constellation to serve the regional consumer by the beginning of 2013.
I. According to the adjusted schedule, the Compass/Beidou system constellation by the beginning of 2013 will include 14 spacecraft, including: 5 spacecraft in the geostationary GEO orbit (58.5 ? E, 80 ? E, 110, 5 ?E, 140?E, 160?E); 5 spacecraft in inclined geosynchronous orbit IGSO (altitude 36000 km, inclination 55°, 118° East); 4 spacecraft in medium-Earth orbit MEO (altitude 21500 km, inclination 55?).
II. Deployment of a global navigation system with a constellation of 36 spacecraft in 2020 (according to other sources - 35 spacecraft, according to third sources - 37 spacecraft), including: 5 spacecraft in geostationary orbit; 5 spacecraft in inclined geosynchronous orbit; 24 spacecraft in medium-Earth orbit 3 spacecraft (location to be specified, possibly orbital reserve).
The tracking stations are equipped with dual-frequency UR240 receivers and UA240 antennas, developed by the Chinese company UNICORE and capable of receiving GPS and Compass signals. 7 of them are located in China: Chengdu (CHDU), Harbin (HRBN), Hong Kong (HKTU), Lhasa (LASA), Shanghai (SHA1), Wuhan (CENT) and Xi'an (XIAN); and 5 more in Singapore (SIGP), Australia (PETH), UAE (DHAB), Europe (LEID) and Africa (JOHA).
The navigator in the Chinese system is not only a receiver, but also a signal transmitter. The monitoring station sends a signal to the user via two satellites. The user's device, after receiving the signal, sends a response signal through both satellites. Based on the signal delay, the ground station calculates the user’s geographic coordinates, determines the altitude from the existing database and transmits signals to the user segment device.
