The positioning accuracy of the GPS module depends on many aspects. For example, the satellite clock difference and orbital difference from the GPS system, the number of visible GPS satellites and geometric distribution, solar radiation, atmosphere, multi -diameter effects, etc. In addition, the same GPS module will also produce different positioning errors due to antenna and feed quality, antenna location and direction, testing time period, open sky and direction, weather, PCB design and other reasons. Even when the same manufacturer of the same manufacturer is tested at the same time when different GPS modules are used to use an antennaer at the same time, the static drift volume will be different.

　　The GPS module is often used as the time benchmark in actual applications, supplemented by the RTC inside the module, which can obtain a very high -precision time reference, which provides a great convenience for product design. As for the GPS speed measuring, it is only an expansion application based on the basis of obtaining latitude.

　　The common antennas of GPS are ceramic flat antennas. This antenna costs low. There are large circuits on the outside, with a single signal direction and a relatively high gain, so the most adopted. But its disadvantage is that the volume is large, and it is easy to be affected by temperature and causes frequency. If the ceramic area is small, it will affect the receiving gain; if it is thin, it will affect the receiving bandwidth of the receiving antenna, and it will also be mostly affected by the source. At present, the effect of good use is 25 × 25 × 4mm3. The ceramic antenna is the best effect when placing vertically upward in actual use.

　　The signal transmission line of the GPS antenna is also very important, including external feedback lines and PCB wiring. The output power is only possible when the impedance matching. Therefore, the entire transmission line must ensure a 50Ω high -frequency impedance. For how to design RF wiring impedance on the PCB, some small software can help you calculate it easily.

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