The positioning accuracy of the GPS module depends on many aspects, such as the satellite clock error and orbit error from the GPS system, the number and Geometric distribution of visible GPS satellites, solar radiation, atmosphere, multipath effect, etc. In addition, the same GPS module will produce different positioning errors due to antenna and feeder quality, antenna position and direction, test time period, Open skies range and direction, weather, PCB design and other reasons. Even when different GPS modules of the same manufacturer and model are tested using antenna diversity simultaneously, there may be differences in static drift.

　　GPS modules are often used as time benchmarks in practical applications, supplemented by the internal RTC of the module, which can obtain highly accurate time references and provide great convenience for product design. As for GPS speed measurement, it is only an extended application that is achieved through simple calculations based on obtaining longitude and latitude.

　　The common antenna for GPS is a ceramic flat antenna, which has low cost, an external active amplification circuit, a single direction of receiving signal, and high gain, so it is most commonly used. But its disadvantage is its large volume and susceptibility to frequency drift caused by temperature. If the ceramic area is reduced, it will affect the reception gain; If made thin, it will affect the receiving bandwidth of the receiving antenna and also be affected by the active amplification part. The currently effective size is 25 × twenty-five × 4mm3. The ceramic antenna performs best when placed vertically upwards in practical use.

　　The signal transmission line of the GPS antenna is also very important, including external feeder lines and PCB routing. The maximum output power is only possible when impedance matching occurs. Therefore, the entire transmission line needs to ensure a high-frequency impedance of 50 Ω. Some small software can help you conveniently calculate how to design RF wiring impedance on a PCB

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