There are many types of GPS satellite receivers, according to the model is divided into geodesic type, total station type, timing type, handheld type, integrated type; according to the use of vehicle-mounted type, ship-mounted type, airborne type, star-carrying type, bullet-carrying type.
Categorized according to the use of the receiver
1. Navigation receiver
This type of receiver is mainly used for the movement of the carrier's navigation, which can give the carrier's position and speed in real time. This type of receiver generally use C / A code pseudo-distance measurement, single-point real-time positioning accuracy is low, generally ± 10m, with the influence of SA for ± 100m. this type of receiver is inexpensive, widely used. According to the different areas of application, such receivers can be further divided into:
vehicle-mounted type -- for vehicle navigation and positioning;
maritime type -- for ship navigation and positioning;
aeronautical type --Used for aircraft navigation and positioning. Due to the fast speed of aircraft operation, the receiver used in aviation requires to be able to adapt to high-speed movement.
Satellite - for satellite navigation and positioning. Since the speed of satellites is up to 7km/s or more, the requirements for receivers are higher.
2. Geodetic receiver
Geodetic receiver is mainly used for precision geodesy and precision engineering surveys. This type of instrument mainly uses the carrier phase observation value for relative positioning, high positioning accuracy. The structure of the instrument is complex and expensive.
3. Timing type receiver
This type of receiver mainly uses GPS satellites to provide high-precision time standards for timing, commonly used in observatories and radio communications in time synchronization.
According to the receiver's carrier frequency classification
Single-frequency receiver
Single-frequency receiver can only receive the L1 carrier signal, the determination of the carrier phase observation value for positioning. Because it can not effectively eliminate the ionospheric delay effect, single-frequency receiver is only suitable for short baseline (<15km) precision positioning.
Dual-frequency receiver
Dual-frequency receiver can simultaneously receive L1, L2 carrier signal. The use of dual-frequency to the ionosphere delay is not the same, you can eliminate the ionosphere on the delay of electromagnetic wave signals, so dual-frequency receivers can be used for up to several thousand kilometers of precision positioning.
By receiver channel number classification
GPS receiver can simultaneously receive multiple GPS satellite signals, in order to separate the signals received from different satellites, in order to achieve the satellite signal tracking, processing and measurement, with such a function of the device is called antenna signal channel. According to the receiver has the channel type can be divided into:
Multi-channel receiver
Sequence through the channel receiver
Multi-multi-channel receiver
By the receiver principle of operation classification
Code correlation receiver
Code correlation receiver is the use of code correlation technology to get pseudo-range observations.
Square type receiver
Square type receivers utilize the squaring technique of the carrier signal to remove the modulating signal to recover the complete carrier signal, and the pseudo-range observation is determined by measuring the phase difference between the carrier signal generated in the receiver and the received carrier signal by a phasor meter.
Hybrid receiver
This instrument is a synthesis of the advantages of the above two types of receivers, both code phase pseudorange can be obtained, as well as the carrier phase observations.
Interferometric receiver
This type of receiver is the GPS satellite as a radio source, the use of interferometric methods, the determination of the distance between the two stations.
After more than 20 years of practice has proved that the GPS system is a high-precision, all-weather and global radio navigation, positioning and timing multifunctional system. GPS technology has developed into a multi-discipline, multi-mode, multi-purpose, multi-model international high-tech industry. Similar to the car GPS terminal, there are positioning cell phones, personal locators, etc. GPS satellite positioning through a third-party positioning services, so you have to pay varying monthly/yearly service fees.
All GPS positioning terminals, there is no navigation function. The cost increases because of the need for additional hardware and software.
The car GPS ads we see on TV are totally different from the car GPS mentioned above. It is a GPS navigation product that first locates when navigation is needed, which is the starting point of navigation, but it cannot transmit the location information to third parties and holders because of the lack of external communication in the navigator. For example, if you put the navigator in your car, and your friend borrows the car and drives away, the navigator can continue to be used and continue to locate, but it can't send the information to you, and you can't find out the location of the vehicle. Academic positioning can only get your own location. The advertised positioning is actually location tracking, and this needs to be done on the premise of academic positioning to inform you of your location by means of communication.
You said I bought a navigation phone that works, think about it, you put the navigation phone in the car, the car is stolen, that phone will call and text you or a third party on its own? It needs to be operated by a human being. That's why navigation terminals don't even have a location function.
Navigation terminals can navigate routes so that you don't get lost in unfamiliar places, delineate routes so that you can reach your destination, tell you your current location, and the surrounding facilities and so on.
China has made a big market in GPS applications. There are a lot of companies that are navigators. But there are also in the GPS industry to do location management.
A variety of GPS/GIS/GSM/GPRS vehicle monitoring system software, GSM and GPRS mobile intelligent vehicle-mounted terminals, the system's secondary development of vehicle monitoring system to build the overall program. The system is widely used in public security, medical, fire, transportation, logistics and other fields. The program is based on NXP's PNX1090 Nexperia mobile multimedia processor hardware and software jointly developed by NXP and partner ALK Technologies. NXP claims that the program provides designers with the ability to build a low-cost, multimedia-rich portable media player with the ability to navigate all the multimedia features required, these multimedia features include: MP3 playback, standard and high-definition video playback and recording, FM radio, image storage, and gaming. nXP replaces a GPS baseband processor with its swGPS Personal software running on the PNX0190 for GPS calculations, which in turn reduces bill-of-materials (BOM) costs and supports field upgrades.
The range of applications associated with following GPS are designed with math and algorithms, and GIS systems, map projections, and coordinate system conversions!
Because of the satellite orbit, satellite clock error, the atmosphere troposphere, ionosphere on the signal, as well as man-made SA protection policy, so that the civil GPS positioning accuracy of only 100 meters. In order to improve the positioning accuracy, differential GPS (DGPS) technology is commonly used to establish a reference station (differential station) for GPS observation, and use the known precise coordinates of the reference station to compare with the observed value, so as to derive a correction number and release it to the public. After the receiver receives the correction number, it compares it with its own observation value, eliminates most of the errors, and obtains a more accurate position. Experiments have shown that using Differential GPS (DGPS), the positioning accuracy can be improved up to 5 meters. It is mainly composed of two main parts, namely; local monitoring center software management platform and remote GPS intelligent vehicle-mounted terminal. The remote GPS intelligent vehicle-mounted terminal transmits data such as location information, running speed, running track, etc. of the vehicle back to the monitoring center, which will immediately analyze and compare these data after receiving them and display the results in the form of normal information or alarm information in two categories to the administrators, who will decide whether or not necessary measures should be taken for the target vehicle.