Test background

In a wharf area in Dongguan City, the 2.4GHz frequency signal is used to carry the operation scheduling. Recently, the strong external interference signal caused the normal use of the scheduling operation, resulting in a large number of delays in the work. The relevant technical department of Dongguan Port conducted an internal self-examination to confirm that all the WIFI devices in the field have no malfunctions of their own. It is necessary to conduct field investigations on the sources of interference signals to ensure the safety of port production.

On February 3, 2021, a unified deployment was made in the Guangdong Provincial Department of Industry and Information Technology, and interference investigations were carried out in a range of nearly 10Km around Dongguan Port to ensure the normal operation of the company during the Spring Festival.

Test process one:

The frequency sweep of the terminal platform operation area found that there are indeed external interference signal characteristics. Since there are WIFI devices covering the same frequency in the field, the testers avoided the busy frequency of the channel, and observed the frequency after 2.48GHz when the channel was relatively idle, and captured the abnormality. The interference signal is shown in the figure below: spectrum analysis, spectrogram, and afterglow spectrum can be clearly seen.

Test process two:

The top (high) of the gantry pendant of the port terminal is also the installation place of the terminal WIFI equipment. Here, the waveform state that the entire 2.4GHz section is lifted and suppressed by the shield can be clearly captured, and the directivity points to the distant oil tank area. The power can reach -80dBm.

Test process three:

Take a boat from the wharf to Lisha Island in the oil tank farm. During the journey, the possibility of interference sources on the Nansha Bridge is ruled out. The interference level value has been maintained at about -80dBm during the whole process. Therefore, the location of the interference source may be considered It is high and the radiation direction is also high plane. It is suspected that there is a major possibility of suppressing emission sources in the oil tank farm on Lisha Island.

Test process four:

Landed on Lisha Island for investigation and testing, and finally located the most suspicious of Dongzhou Petroleum Company on the island. The highest power level has reached about -60dBm, and it was found that in addition to 2.4GHz, 5.8GHz was also suppressed.

Test process five:

On the roof of the oil company, by coordinating the installation of the drone suppression system on the roof, it can suppress 1.5GHz/2.4GHz/5GHz. After confirming that the interference waveform disappears after the shutdown, the port terminal WIFI dispatching system returns to normal.

More other interference search cases are as follows. If you need to know related cases, please contact our sales, thank you.

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