In 1966, the Chinese Academy of Sciences began to prepare for the construction of the short wave time service station, as the main task in building the Northwest Time Service Station (named Shaanxi Astronomy Observatory later). According to the requirement of "close to the mountain and live in the cave ", the station was located on Jinzhi Mountain, Pucheng, Shaanxi Province, coded as "326 project".
In 1970, the time service station was almost completed. Therefore Zhou Enlai, prime minister of China at that time, gave instructions to start the trial broadcast personally. The station, with “BPM” as its call sign, reached a millisecond-level timing accuracy, whose signal were transmitting at all these frequencies: 2.5 MHz, 5 MHz, 10 MHz and 15 MHz Since 1981, the short wave time service station of the Shaanxi Astronomy Observatory has been officially undertaking the task of short wave time service in China, replacing BPV time service station of Shanghai Observatory.
The Old Short Wave Time Service Station in Pucheng (Image Credit: National Time Service Center, CAS)