Factors affecting the positioning accuracy of the GPS module

By sdga:NiceRF Wireless Technology Co., Ltd

The operation of GPS modules requires the reception of signals from navigation satellites, which are processed and fed back to devices such as vehicle navigation systems. This process is self-operating and cannot be intervened by personnel. Therefore, there are factors that may lead to insufficient GPS positioning accuracy.

Factors affecting the positioning accuracy of the GPS module

1. GPS module start time

Firstly, the GPS module needs to be powered on to obtain positioning data, which is referred to as a cold start. This process involves starting up the GPS in an unfamiliar environment until it establishes connection with surrounding satellites and calculates the coordinates. This includes scenarios such as initial usage, battery depletion leading to loss of ephemeris data, and it can drift more than 1,000 kilometers away when it's turned off.

GPS module working principle diagram

Cold start is a necessary hardware start-up process that prepares the GPS module to enter the working state. If the cold start time is too long, it can result in slow navigation positioning, which directly affects the time required to capture the positioning satellite. Additionally, hot startup is available when the GPS module is not displaced too much from the last shutdown location, resulting in a pure hardware boot time of approximately 1 second, with an additional 1 second required for pure hardware to capture the signal. The startup time directly impacts the efficiency of the GPS module's signal capture, making this parameter an important consideration.

GPS module GPS01-TD is applied to vehicle navigator

2. Satellite error

The GPS module plays a passive role in navigation positioning, as it is responsible only for receiving signals from positioning navigation satellites. Therefore, the problem of inadequate positioning can arise due to errors in the received signal, such as satellite errors, which cannot be corrected. In such cases, changing the location or time point during positioning may help to improve accuracy.

3. Communication error

The transmission of positioning navigation signals from satellites to receivers involves factors such as time and distance, which can cause delays and errors such as stream delay, multi-path errors, and relativity errors. It's important to note that these factors are not indicative of poor GPS module performance.

4. Signal receiving error

The accuracy of positioning can also be affected by the signal receiving environment. Factors such as noise, delay, and wireless phase center errors can hinder signal reception. To improve signal reception, it is recommended to check if the antenna is properly exposed and if the surrounding environment is relatively open. Re-obtaining positioning information may be necessary.

5. GPS module positioning accuracy

The GPS module's positioning accuracy comprises of three aspects: horizontal positioning accuracy, height positioning accuracy, and speed positioning accuracy. While higher accuracy is desirable in theory, it is not necessary to pursue extreme precision since the GPS/Galileo/BDS/Glonass satellite navigation system also has inherent errors. NiceRF's GPS module GPS01-TD boasts a horizontal positioning accuracy of less than 3 meters, height positioning accuracy of less than 4.5 meters, and speed measurement accuracy of less than 0.1 meters.

6. Sensitivityof GPS module

This mainly refers to the cold start sensitivity of signal capture and tracking, which indicates the minimum transmitting power of the satellite signal that can be detected after a cold start. Once the satellite signal is captured, the GPS signal can navigate with a minimum signal strength of -148dBm, and track with a sensitivity of -166dBm.

That’s all about the factors that affect the positioning accuracy of the GPS module and hope it’s helpful for everyone. For consultation, please contact NiceRF (Email: sales@nicerf.com).