There are many difficulties in creating real satellite reception conditions in the laboratory environment. GPS simulator can simulate satellite signals instead of satellite receivers. The advantage of GPS simulator in replacing the satellite receiver is analyzed theoretically.

The GPS position simulator can simulate the output of satellite signals in different environments and geographical locations, in principle, it can replace real satellite signals. Using the theoretical analysis method, using different time synchronization output signals (1PPS second pulse, B code and PTP precise time message) as the benchmark, we explore whether the GPS position simulator can replace the satellite receiver to complete the detection of the time synchronization system in the power system.

The GPS position simulator simulates the whole working process of satellite signal reception from 3 aspects: space satellite to track link and user reception, and even considers the earth rotation and Doppler effect. Compared with the satellite receiver, the GPS position simulator still has obvious advantages in the experimental test.

Reproducible test. Researchers can conduct experiments repeatedly under the constant test conditions to improve the accuracy of measurement results.

Accuracy test. The simulator can adjust various parameters such as satellite signal power to meet different experimental requirements.

Scene customization. Different weather conditions and atmospheric parameters can be simulated according to experimental needs. The orbit satellite has a high precision time reference with a precision of 10-13, and the satellite signal emitted has a very high quality of time.

The SYN5203 satellite simulator itself has a crystal clock with a time accuracy of 10-9, which is inferior to the real time accuracy of the real signal, but it still meets most of the experimental detection requirements. If a higher precision time benchmark is needed, an external clock reference source with high precision frequency output function can be configured for the simulator.

The principle of the test is similar to that of using the satellite receiver as the reference source, and the satellite simulator is used instead of the satellite receiver to repeat the experiment process.

The SYN5203 satellite simulator gradually reduces the number of visible satellites to more than 5 of the tracking star group of the time receiver, and gradually increases the pseudo range of one of the satellites. By means of the receiver maintenance terminal, it can observe whether the receiver can detect this change in time, and exclude the star which can not be tracked from the star. This scenario can be used to test the self timer of the time receiver. Integrity monitoring function. Similarly, for dual-mode receiver, we can use satellite simulator to set up a single star group with fewer than 4 visible stars, and the total number of stars can be at least 4. The satellite simulator gradually reduces the number of visible stars of a certain constellation until it is completely invisible, and does not operate on another star cluster. This scenario can be used to test the alarm function of dual mode timing receiver to maintain terminal.

The receiver automatically switches capability and changes in output performance when switching. Although the mode of operation can be forced through the receiver network management, the output performance of the time receiver is measured when the working mode changes, and this method is not more reliable than using the satellite simulator operation, because the use of the satellite simulator completely cuts off the receiver's ability to track and use another navigation star cluster from the signal source.

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