BPM is the People's Republic of China's national time signal service, operated by the Chinese Academy of Sciences. It is located at .[1]
It is broadcast from the National Time Service Center in Pucheng county about 70 km northeast of Lintong.[1] (Along with an intermittent long-wave time code BPL on 100 kHz).
It broadcasts at 2.5, 5.0, 10.0, and 15.0 MHz, the same frequencies as WWV and WWVH.
There is also a low-frequency time code broadcast at 68.5 kHz.[2] BPC Shangqiu Low-Frequency Time-Code Radio Station (Shangqiu City, Henan Province, coordinates:) [3] was cooperatively constructed by the National Time Service Center of the Chinese Academy of Sciences and Xi’an Gaohua Technology Co., Ltd.[2]
BPM transmits different signals on a half-hour schedule [3], modulated with 1 kHz audio tones to provide second and minute ticks:
| Minute | Duration | Transmission | |
|---|---|---|---|
| 00 | 30 | 10 | UTC: 10 ms second ticks, 300 ms minute ticks. |
| 10 | 40 | 5 | Carrier (no time code) |
| 15 | 45 | 10 | UTC: 10 ms second ticks, 300 ms minute ticks. |
| 25 | 55 | 4 | UT1: 100 ms second ticks, 300 ms minute ticks. |
| 29 | 59 | 1 | Station identification: Morse call sign for 40 seconds, then voice announcement for 20 seconds. |
BPM is idiosyncratic in that it transmits UT1 time between minutes 25 through to 29 and 55 through to 59, which creates an odd click-beep effect when heard below a stronger time signal station such as WWV.[5]
BPC includes both a conventional amplitude modulated time code and an additional spread-spectrum time code, about which little is known.[5]
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![[4]](http://www.time.ac.cn/jianjie/1.jpg){kind=link}