Location is a basic and indispensable information of the Internet of Things, and higher-precision positioning information can bring higher benefits and value. Regarding location services, the application that ordinary people are most familiar with is navigation. For most car owners, it may be difficult to move without navigation, and autonomous driving puts forward higher requirements for positioning accuracy. High-precision positioning services and high-precision timing services are becoming new hot spots in the market. In the current location-based service market, the demand for space-time services in areas such as smart transportation, virtual reality, robotics, industrial interconnection, municipal IoT, and smart wearables is gradually increasing. On the whole, the positioning accuracy of outdoor location services is gradually approaching the demand for high-precision positioning such as 1 meter, sub-meter level, and centimeter level, and the timing accuracy of satellite timing services is also gradually approaching the time synchronously below 10 ns.
GPS (Global Positioning System) is a global positioning system. The principle is to achieve precise positioning by receiving signals of a certain frequency band transmitted by GPS. According to the classification of signals received in different frequency bands, it can be divided into dual-frequency GPS and single-frequency GPS. The main difference between frequency GPS and dual-frequency GPS is the number of frequencies they use. Dual-frequency GPS means that the dual-frequency receiver can receive L1, L2 or L5 frequency band signals at the same time, and single-frequency only receives L1 frequency band signals.
Single frequency GPS module
The single-frequency GPS module can only receive satellite signals in the GPS L1 frequency band. As long as the GPS positioning can receive the positioning signals of four satellites, it can perform positioning with an error within 5-10 meters. The GPS modules developed by SKYLAB all use MTK high-performance positioning chips, so they can receive more than 10 satellite positioning signals, so the positioning accuracy can reach 2.5-3 meters. The GPS module is equivalent to a satellite signal receiver in the driving recorder. By continuously capturing and tracking satellite signals, according to the standard specification of the NMEA-0183 protocol, the received satellite information data is transmitted to the driving recorder through the UART serial port. According to the data, the positioning calculation is carried out in a certain way, and finally the latitude and longitude, altitude, speed, time and other information required by the driving recorder are obtained.
Dual frequency GPS module
The dual-frequency GPS module can receive satellite signals in the GPS L1 and GPS L5 frequency bands at the same time, and can eliminate the influence of the ionosphere on the delay of the electromagnetic wave signal by using the difference in the delay of the ionosphere between the dual-frequency and GPS; in addition, the dual-frequency GPS module can also By observing at two frequencies, the resolution of the ambiguity of the entire circumference is accelerated. For example, SKG122S/SKG122Y/SKG123, a new dual-frequency multi-mode positioning module launched by SKYLAB, L1+L5 dual-frequency positioning makes positioning faster, higher precision, and more reliable product performance.
What are the differences between a single-frequency GPS module and a dual-frequency GPS module?
The difference between GPS dual-frequency and single-frequency is mainly reflected in parameters such as chips, frequency bands, positioning accuracy, and timing accuracy:
Chips are different: SKYLAB single-frequency GPS modules mostly use MediaTek chip solutions, MT3337 and MT3339, while SKYLAB dual-frequency GPS modules use Huada and Airoda AG3335 chip solutions;
The frequency bands are different: the single-frequency GPS module can only receive satellite signals in the GPS L1 frequency band, and the dual-frequency GPS module can simultaneously receive satellite signals in the GPS L1 and GPS L5 frequency bands;
Single-frequency GNSS module: refers to the positioning module that only supports the L1 frequency band. The L1 frequency bands include: GLONASS L1OF, GPS L1CA, QZSS L1CA, SBAS L1, QZSS L1 SAIF, Galileo E1(E1B+E1C), BeiDou B1l;
Dual frequency GNSS module: refers to the positioning module that supports L1+L5 dual frequency bands. The L1 frequency bands are: GLONASS L1OF, GPS L1CA, QZSS L1CA, SBAS L1, QZSS L1 SAIF, Galileo E1(E1B+E1C), BeiDou B1l; L5 The frequency bands are: GPS L5, QZSS L5, Galileo E5a, BeiDou B2a;
The positioning accuracy is different: the dual-frequency GPS module can receive satellite signals in the GPS L1 and GPS L5 frequency bands at the same time, and the delay of the ionosphere by using the dual-frequency is different, which can eliminate the influence of the ionosphere on the delay of electromagnetic wave signals; The high-frequency GPS module can also accelerate the resolution of the ambiguity of the entire channel by observing at two frequencies. For example, the positioning accuracy of the dual-frequency multi-mode positioning module SKG122S/SKG122Y/SKG123L/SKG123N/SKG8212 can reach about 1.5 meters. The L1+L5 dual-frequency positioning makes positioning faster, with higher precision and more reliable product performance.
The above is the main difference between single-frequency GPS and dual-frequency GPS. I hope it can help engineers in need. For more subtle needs, you can download the single-frequency GPS module and the dual-frequency GPS module specification for detailed comparison. Direction specification download: SKYLAB01's blog_CSDN blog-GPS positioning, wireless communication, UWB indoor positioning field blogger