BPC (time signal)

BPC is the callsign of a time signal broadcasting from the BPC Shangqiu Low-Frequency Time-Code Radio Station, cooperatively constructed by the National Time Service Center of the Chinese Academy of Sciences and Xi’an Gaohua Technology Co., Ltd., since April 25, 2002.

BPC transmits a time signal on 68.5 kHz, which can be used for synchronizing radio controlled clocks. As opposed to other time signal transmitters, the signal format is not published openly; a special license is required. The transmission site is situated near Shangqiu, Henan Province[1] at 34.457°N 115.837°E / 34.457; 115.837.[2]

BPC broadcasts at 90 kW for 20 hours per day, with a 4-hour break from 05:00–09:00 (China Standard Time) daily (21:00–1:00 UTC).[3] BPC includes both conventional amplitude modulated time code and additional spread-spectrum time code, about which little is known.[4]

Time code
BPC bit coding
DurationBit 1
Bit 2
100 ms0
0
200 ms0
1
300 ms1
0
400 ms1
1
BPC time code[5]
SecondWeight Bit 1
Weight Bit 2		MeaningSecondWeight Bit 1
Weight Bit 2		Meaning
00-blank1012
P1		Hour (0=AM 1=PM)
Even parity over 01-09
0140
20		Second (00, 20 or 40)110
16		Day of month
020
0		Unused128
4
038
4		Hour (00 - 11)132
1
042
1		148
4		Month
0532
16		Minute152
1
068
4		1632
16		Year (from 2000)
072
1		178
4
080
4		Day of week
1=Monday
7=Sunday		182
1
092
1		1964
P2		Year MSB
Even parity over 11-18

References
  1. "Low-frequency radio time signals". Cl.cam.ac.uk. Retrieved 2011-10-20.
  2. "::时间服务::". Archived from the original on 2012-06-17. Retrieved 2013-03-16.
  3. 西安高华科技有限公司 (2020-01-10). "河南商丘BPC电波塔发播时间公布" (in Chinese).
  4. 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..1XF, doi:10.1117/12.885845, S2CID 110865336
  5. Description (in Chiness)
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