Chen Ping, leader of the Huangyan Dao Amateur Radio DXpedition Team, recalled that international amateur radio enthusiasts carried out four DXpeditions to Huangyan Dao between 1994 and 2007. 

Before each expedition, they had to confirm that Huangyan Dao was not subject to a sovereignty dispute. Amateur radio operators from Germany and the United States obtained official letters from the Philippine Embassy in West Germany and the Philippine Department of Environment and Natural Resources, both confirming that Huangyan Dao did not belong to the Philippines. The documentary evidence leaves no room for doubt.