The interference source is that the radio signal (3887khz) received by Shandong daily is interfered. Using traditional portable equipment and mobile monitoring vehicle, the signal is located in the west of Jinan City. However, the signal strength will increase near any base station, resulting in the monitoring vehicle and portable equipment can not accurately give a signal direction. The UAV search process is as follows:

The above figure shows all the DF lines of this test. The red point is the take-off point, and the black Pentagram is the interference source position. The sequence of the tests is from the top to the bottom of the figure, four times in total. In the right figure, it can be seen that in the second DF, once the DF is in obvious reverse direction, and once the direction indicating line is in the north direction. The relative deviation of the two times is the biggest in the whole process.

The signal will be enhanced near the base station, which may lead to multiple direction finding and fail to meet a satisfactory point. Because there are only two batteries, the test method is used instead. When the aircraft rotates in the air, the maximum value is determined by observing the software interface, and the bellmouth direction is the maximum signal direction. Test these base stations one by one at a short distance from the aircraft near the base station, and eliminate these base stations as interference sources one by one. Finally, it is found that the interference source is installed on the base station, and the interference signal strength near the base station is significantly improved compared with that around other base stations. The interference device is shown in the figure below:

In the process of this search, our company's aircraft equipment has the advantage of always being able to give a unified direction and take off quickly to monitor and eliminate the base station (suspected interference source) that makes the signal rise. The traditional ground equipment can not give a unified direction because of the influence of the characteristic that the intensity of the signal will rise near the base station.

For the special search of satellite interference, the pitch angle of the antenna is adjusted by 10 degrees automatically for each turn of the aircraft in the air, so as to finally calculate a signal position. There are also applications in this search process. The test results are as follows:

The interference source is at the bottom left of the modified image, and the black mark is the take-off point. The red mark points in the figure are the algorithm positions given by two times of direction finding in the same place, the same height, the same number of rotations. There is a big difference.