BPM is the People's Republic of China's national time signal service, operated by the Chinese Academy of Sciences. It is located at 35°0′N 109°31′E / 35°N 109.517°E / 35; 109.517Coordinates: 35°0′N 109°31′E / 35°N 109.517°E / 35; 109.517.[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.
[edit] BPC low-frequency service
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:34°56′54″N 109°32′34″E / 34.94833°N 109.54278°E / 34.94833; 109.54278 (BPC Time Signal Transmitter)) [3] was cooperatively constructed by the National Time Service Center of the Chinese Academy of Sciences and Xi’an Gaohua Technology Co., Ltd.[2]
[edit] Transmission format
BPM transmits different signals on a half-hour schedule [3], modulated with 1 kHz audio tones to provide second and minute ticks:
BPM transmission schedule [4][5]
| 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.[6]
[edit] References
- ^ Time Signals, BIPM, p. 78, ftp://ftp2.bipm.org/pub/tai/scale/timesignals.pdf, retrieved 2011-04-20
- ^ Markus Kuhn, Low-frequency radio time signals, http://www.cl.cam.ac.uk/~mgk25/time/lf-clocks/, retrieved 2011-04-29
- ^ G-Shock: China Signal (BPC) Series, http://www.javys.com/casio/series.php?series_id=BP0001, retrieved 2011-04-29
- ^ http://maia.usno.navy.mil/ser7/finals.all Each line starts with yymmdd, DUT1 is third-last column.
- ^ Marco1971 (2007-01-23), Re: A question about Wave Ceptor frequency reception, http://forums.watchuseek.com/f17/question-about-wave-ceptor-frequency-reception-46487.html#post258489, retrieved 2011-04-29
- ^ Feng, Ping; Wu, Guichen; Bai, Yan; Ding, Xiaofeng (August 2010), Tan, Jiubin; Wen, Xianfang, eds., "Additional spread spectrum modulation timing method in BPC", Sixth International Symposium on Precision Engineering Measurements and Instrumentation. Proceedings of the SPIE, Proceedings of SPIE 7544: 75441X–75441X–6, Bibcode 2010SPIE.7544E..68F, doi:10.1117/12.885845
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![[4]](http://www.time.ac.cn/jianjie/1.jpg){kind=link}