The Difference Between GNSS and GPS

The GPS navigation module is an integrated circuit chip equipped with RFRFRF processing chip, wifi chip, core CPU and related peripheral circuits. The more common GPS positioning module is called the user part, which accepts and modulates the live C/A code signal of the communication satellite like a "recorder", and the center frequency is 1575.42MHz. The GPS module does not transmit a signal and is in passive positioning. Measure and calculate the pseudo-range of each communication satellite, and use the distance intersection method to calculate the four main parameters of the receiver's latitude and longitude, layer, relative height, and time calibration. The characteristic is that the positioning point is faster, but the deviation is large. The GPS module uses the serial port communication to continuously export the NMEA format positioning information and auxiliary information, allowing the recipient to choose the APP to use.

1. GPS module classification

GPS modules can be divided into single-module and multi-channel components, and can also be divided into smart wearable device GPS modules, vehicle business-scale GPS modules, unmanned aircraft GPS modules and extensive industrial production GPS modules according to their main uses.

 

2. Cognition of the manual

GPS/BDS/GLONASS/GALILEO multi-system navigation and positioning module is a series of high-quality multi-system GNSS modules released by Skylab for vehicle-mounted, engineering projects, consumer applications, etc., with high positioning accuracy, low power consumption, and compact

This series of modules maximizes sensitivity while minimizing loss of system software functionality. The internal structure Flash can update the program flow to adapt to various APP application software. There is an additional front LNA to improve the RF characteristics, which is beneficial to the integration with the wireless antenna, and the front SAW filter improves the anti-interference ability.

 

3. Model selection of GPS module

The performance parameters of the GS module mainly include receiving sensitivity, positioning time, position accuracy, function loss, time accuracy, etc.

 

1. Receiving sensitivity; receiving sensitivity is the minimum signal receiving output power at which the receiver can properly remove the effective signal.

The receiving sensitivity of wireless data transmission is similar to the English listening after communication. By improving the receiving sensitivity of signals, wireless communication equipment can capture weak signals more strongly. In that way, with the increase of the transmission distance and the weakening of the received signal, the highly sensitive wireless communication equipment can still obtain data, maintain a stable connection, and greatly increase the transmission distance.

 

2. Positioning time; positioning time refers to the time for GPS equipment to automatically and gradually position itself, generally based on seconds. By this time, the GPS device will send signals to the GPS positioning communication satellites, gradually clarifying its location. In addition, it also includes the first run, cold start, hot (warm) start positioning time.

 

The operating positioning time of the module differs depending on the startup mode. Generally speaking, the cold start time refers to the situation when the internal structure of the module does not store all information that is conducive to positioning, including the ephemeris, time, etc., and the general standard is within 1 minute; the hot start time refers to the internal structure of the module. There is a new communication satellite calendar (generally less than 2 hours), but the time error is relatively large, and the general nominal pressure is within 45 seconds; the hot start time means that the standby time is within 20 minutes, and the RTC time deviation is relatively small. . The general nominal pressure is within 10 seconds; the recapture time is the same as recapturing the communication satellite when the vehicle passes through the tunnel and leaves the tunnel for construction. The general nominal pressure is within 4 seconds.

 

If the module is placed very long after positioning, or the module is transported hundreds of kilometers away after positioning, there is an ephemeris inside the module, but the ephemeris is likely to be incorrect, and it may not be possible to refer to it . Under various conditions, the positioning time may be more than three to five minutes. Therefore, the most typical GPS module will delete relevant information such as the ephemeris inside the module when it leaves the factory, so that customers can quickly locate it according to the cold start method after obtaining the module.

 

3. Position accuracy; position accuracy refers to the degree of consistency between the acquired plane coordinates of a spatial point and its real plane coordinates.

The positioning accuracy can also be understood under the premise of static and dynamic, and the actual effect of dynamic positioning is better than that of static data positioning. The positioning parameters in the GS module are tested in a completely open sky with high-quality satellite signals. Therefore, it is difficult to achieve standard positioning time and positioning accuracy for basic detection.

 

4. Electricity consumption; in other words, the loss of power consumption refers to the difference between equipment, equipment, etc. input power and output power.

 

With the rapid development of electronic information technology and microelectronics technology, the application scope of embedded operating system is becoming more and more common. Environmental protection and energy saving are the trend of economic globalization. For example, many processing chips of computers used to use 5V power distribution, but now they use 3.3V, 1.8 V, gives the concept of emerald green system. Many manufacturers pay special attention to the low power consumption problem of GPS modules. The low power consumption design of the power supply circuit and system has always been the key factor to be considered by microelectronics technical engineers when designing. The GPS module function loss value developed and manufactured by Beitian is all tens of mA, which are all low energy consumption modules. Technical engineers You can choose with confidence.

 

5. Time accuracy; time accuracy is to screen the time measurement according to the needs of each customer, and it is mainly a method for detection. Time accuracy can be divided into nanosecond (ns), picosecond laser (ps), minute second (us), ms (ms), second), min (min), time (h).