GPS Test Introduction

GPS test schematic diagram

GPS testing needs to be conducted in an electromagnetic shielding room, using the E4438C\N5182B vector signal source to simulate satellite transmission signals, using a multi-probe test system, omnidirectional scanning of the strength of GPS signals received by GPS receivers at different locations. In order to ensure effective communication between the mobile phone and the computer, the computer and the mobile phone need to be connected to the same local area network through a wireless router (tested via WIFI). This solution provides the following five test modes for customers to choose from:

1. Multi Satellites (multi-satellite sensitivity test)

The signal source simulates eight satellite signals and transmits at a fixed power. The situation of the mobile phone receiving this GPS signal from different directions is collected to obtain the mobile phone's ability to receive GPS signals in various directions. In the direction where the mobile phone receives the strongest signal, the power of the signal source is reduced to find the critical point power that the mobile phone can locate. Based on the comparison between the critical point power obtained and the mobile phone's ability to receive signals in various directions, the GPS sensitivity and 3D directional map of the mobile phone can be calculated.

2. Multi Satellites Estimate

It is assumed that the mobile phone can achieve positioning after the received GPS signal reaches a certain threshold. The signal source simulates eight satellite signals and transmits at a fixed power. The GPS sensitivity and 3D direction map of the mobile phone are estimated based on the GPS CN0 received by the mobile phone in various directions.

3. Single Satellites Estimate

The algorithm is similar to multi-star estimation. Single-star estimation simulates the signal of a single star for testing. The signal source power is adjusted so that the effective readings are within the linear range of the signal. This makes the readings more reflective of the ability to receive signals at that point. Finally, the sensitivity and 3D direction diagram of the mobile phone receiving GPS signals are calculated based on the CN0 values ​​received by a single star in each direction.

4. CN0 Measurement (single star CN0 test)

Compared with Single Satellites, this mode does not need to detect whether the current point result is in the linear region. The test result is the arithmetic mean of CN0 when the signal power is -130dB.

5. MSCN0 Measurement (multi-satellite CN0 test)

After the scanning is completed and the receiver's ability to receive GPS signals in all directions is obtained, the points that are not in the linear region and NAN are found and re-measured until all points are in the linear region, and then the arithmetic mean of CN0 is calculated.

Comparison of various modes:

· Multi-star sensitivity test is a standard method for measuring the sensitivity of mobile phones. However, finding the critical point of sensitivity takes a long time in situations where high precision is required. This method is a standard and reliable method.

The multi-satellite estimation test mode saves the step of finding sensitivity, and the test time is short. As long as the CN0 data reported by the mobile phone is accurate, the test result is close to the actual value of the mobile phone. The test is very stable and suitable for antenna factories to conduct horizontal comparison tests.

The single-satellite estimation test mode takes longer to test than the multi-satellite estimation test mode because the single-satellite estimation mode requires the results of all points to be within the linear region. It can better reflect the strength of the mobile phone's signal reception ability. The test is very stable and suitable for antenna manufacturers to conduct horizontal comparison tests.

Comparison of GPS test stability in various modes

The above methods and data are based on the multi-probe test system and GPS test software provided by Shenzhen Sunyield Technologies Co., Ltd. In order to provide a solution that can truly and accurately reflect the performance of GPS receivers in actual use, Sunyield Technologies has invested a lot of manpower and material resources in the research and development of GPS testing. After a large number of experiments and repeated verifications, a GPS test solution that can be repeatedly executed and accurately measured has been obtained. The solution provides four test modes for customers to choose from, which can display the distribution and direction map of the strength of the mobile phone GPS signal.