BPM (time service)
{{Short description|People's Republic of China time signal}}
BPM is the call sign of the official short-wave time signal service of the People's Republic of China, operated by the Chinese Academy of Sciences, broadcasting from CAS's National Time Service Center in Pucheng County, Shaanxi at {{Coord| 34|56|55.96|N|109|32|34.93|E|type:landmark_region:CN-61|display=it}}, roughly 70 km northeast of Lintong,{{cite web
| url = http://english.ntsc.cas.cn/rs/fs/200909/t20090917_39104.html
| title = National Time Service Center: Facilities
}} along with NTSC's long-wave time signal BPL on 100 kHz.
BPM is broadcast at 2.5, 5.0, 10.0, and 15.0 MHz, the same frequencies as WWV and WWVH, following the schedule listed below:{{cite web
|title=短波授时台
|url=http://www.time.ac.cn/center/222.html
|website=National Time Service Center
|url-status=dead
|archive-url=https://web.archive.org/web/20150410130817/http://www.time.ac.cn/center/222.html
|archive-date=2015-04-10
}}
| class="wikitable" | ||
| MHz | UTC | CST |
|---|---|---|
| 2.5 | 7:30-1:00 | 15:30-9:00 |
| 5 | 0:00-24:00 | 0:00-24:00 |
| 10 | 0:00-24:00 | 0:00-24:00 |
| 15 | 1:00-9:00 | 9:00-17:00 |
Transmission format
{{Listen|filename=Bpm_cut.ogg|title=Sample of BPM time signal|description=The BPM time signal, recorded at 2007-01-07 in Beijing, {{Duration|m=5|s=21}}}}
{{Listen|filename=BPM_5_MHz_record,_start_at_21-07-58_18_Jul_2018.ogg|title=BPM time signal with 125 Hz sub-carrier|description=The BPM time signal, recorded at 2018-07-18 on WebSDR from Netherlands, {{Duration|m=1|s=4}}}}{{Listen
| filename = Bpmtm.wav
| title = BPM time signal with 100 Hz sub-carrier
| description = The BPM time signal, recorded at 2023-10-13 on KiwiSDR from Japan, 18:07
}}
{{Listen
| filename =
| title =
}}
BPM transmits different signals on a half-hour schedule, modulated with 1 kHz audio tones to provide second and minute ticks:
| style="text-align:center" class="wikitable"
|+BPM transmission schedule{{cite web | url = http://forums.watchuseek.com/f17/question-about-wave-ceptor-frequency-reception-46487.html#post258489 | title = Re: A question about Wave Ceptor frequency reception | author = Marco1971 | date = 2007-01-23 | access-date = 2011-04-29 }} ! colspan=2 | Minute !! Duration !! Transmission | |||
| 00 | 30 | 10 | align=left | UTC: 10 ms second ticks, 300 ms minute ticks, in advance by 20 ms.BIPM Annual Report on Time Activities – [https://web.archive.org/web/20211010023818/ftp://ftp2.bipm.org/pub/tai/scale/TIMESIGNALS/timesignals.pdf Time Signals], retrieved 2011 September 12. BCD time code on 100 Hz sub-carrier.[https://bbs.pku.edu.cn/attach/fc/ac/fcac420edd48d7bd/BPM%E7%9F%AD%E6%B3%A2%E6%97%B6%E7%A0%81%E6%8E%88%E6%97%B6%E5%8F%91%E6%92%AD%E6%8A%80%E6%9C%AF%E6%96%B9%E6%A1%88_%E8%92%99%E6%99%BA%E8%B0%8B.pdf Dissemination scheme of BPM shortwave time code time-service] (in chinese), retrieved 2018 August 20. |
| 10 | 40 | 5 | align=left | Carrier (no time code) |
| 15 | 45 | 10 | align=left | UTC: 10 ms second ticks, 300 ms minute ticks, in advance by 20 ms. BCD time code on 100 Hz sub-carrier. |
| 25 | 55 | 4 | align=left | UT1: 100 ms second ticks, 300 ms minute ticks. |
| 29 | 59 | 1 | align=left | Station identification: Morse call sign for 40 seconds, then voice announcement "BPM 标准时间标准频率发播台" ("BPM standard time, standard frequency transmission station") twice 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 especially when UT1 seconds are halfway between UTC seconds, close to a leap-second event.{{cite web
|url = http://tufi.alphalink.com.au/time/time_hf.html
|title = HF (SW) Radio - Time NZ & A
|access-date = 2011-04-25
|archive-url = https://archive.today/20121230125806/http://tufi.alphalink.com.au/time/time_hf.html
|archive-date = 2012-12-30
|url-status = dead
}}
| class=wikitable style="text-align:center;"
! Bit | Weight | Meaning | Ex
|rowspan=21| ! Bit | Weight | Meaning | Ex
|rowspan=21| ! Bit | Weight | Meaning | Ex |
| bgcolor=lightblue| :00 | bgcolor=lightblue colspan=3| No 125 Hz (minute mark)
| :20 | 1 | rowspan=7 | Day of month Example: 28 | 0
| :40 | 1 | rowspan=9| Year Example: 06 | 0 | ||
| :01 | 1 | rowspan=8| Minutes Example: 23 | 1
| :21 | 2 | 0
| :41 | 2 | 1 | ||
| :02 | 2 | 1
| :22 | 4 | 0
| :42 | 4 | 1 | |||
| :03 | 4 | 0
| :23 | 8 | 1
| :43 | 8 | 0 | |||
| :04 | 8 | 0
|bgcolor=lightgrey| :24 | bgcolor=lightgrey| 0 | bgcolor=lightgrey| 0
|bgcolor=lightgrey| :44 | bgcolor=lightgrey| 0 | bgcolor=lightgrey| 0 | |||
| bgcolor=lightgrey| :05 | bgcolor=lightgrey| 0 | bgcolor=lightgrey| 0
| :25 | 10 | 0
| :45 | 10 | 0 | |||
| :06 | 10 | 0
| :26 | 20 | 1
| :46 | 20 | 0 | |||
| :07 | 20 | 1
|bgcolor=lightgrey| :27 | bgcolor=lightgrey| 0 | rowspan=2 bgcolor=lightgrey| Reserved, always 0. | bgcolor=lightgrey| 0
| :47 | 40 | 0 | ||
| :08 | 40 | 0
|bgcolor=lightgrey| :28 | bgcolor=lightgrey| 0 | bgcolor=lightgrey| 0
| :48 | 80 | 0 | |||
| bgcolor=lightpink
| :09 | P1 | Marker | M
| :29 | P3 | Marker | M
| :49 | P5 | Marker | M |
| :10 | 1 | rowspan=7| Hours Example: 19 | 1
| :30 | 1 | rowspan=6 | Month Example: 02 | 0
| :50 | + | DUT1 sign (1=positive) | 1 |
| :11 | 2 | 0
| :31 | 2 | 1
| :51 | 0.1 | rowspan=4| DUT1 magnitude (0 to 0.9 s) DUT1 = UT1−UTC Example: +0.5 s | 1 | ||
| :12 | 4 | 0
| :32 | 4 | 0
| :52 | 0.2 | 0 | |||
| :13 | 8 | 1
| :33 | 8 | 0
| :53 | 0.4 | 1 | |||
| bgcolor=lightgrey| :14 | bgcolor=lightgrey| 0 | bgcolor=lightgrey| 0
|bgcolor=lightgrey| :34 | bgcolor=lightgrey| 0 | bgcolor=lightgrey| 0
| :54 | 0.8 | 0 | |||
| :15 | 10 | 1
| :35 | 10 | 0
|bgcolor=lightgrey| :55 | bgcolor=lightgrey| 0 | rowspan=2 bgcolor=lightgrey| Reserved, always 0. | bgcolor=lightgrey| 0 | ||
| :16 | 20 | 0
|bgcolor=lightgrey| :36 | bgcolor=lightgrey| 0 | rowspan=3 bgcolor=lightgrey| Reserved, always 0. | bgcolor=lightgrey| 0
|bgcolor=lightgrey| :56 | bgcolor=lightgrey| 0 | bgcolor=lightgrey| 0 | ||
| bgcolor=lightgrey| :17 | bgcolor=lightgrey| 0 | rowspan=2 bgcolor=lightgrey| Reserved, always 0. | bgcolor=lightgrey| 0
|bgcolor=lightgrey| :37 | bgcolor=lightgrey| 0 | bgcolor=lightgrey| 0
| :57 | LS | Leap second | 0 | |
| bgcolor=lightgrey| :18 | bgcolor=lightgrey| 0 | bgcolor=lightgrey| 0
|bgcolor=lightgrey| :38 | bgcolor=lightgrey| 0 | bgcolor=lightgrey| 0
|bgcolor=lightgrey| :58 | bgcolor=lightgrey| 0 | bgcolor=lightgrey| Reserved, always 0. | bgcolor=lightgrey| 0 | ||
| bgcolor=lightpink
| :19 | P2 | Marker | M
| :39 | P4 | Marker | M
| :59 | P0 | Marker | M |
References
{{reflist}}
External links
- {{YouTube|id=yuQPjgK6hjc|title=Recorded video of the broadcast BPM time signal}}
- [http://english.ntsc.cas.cn National Time Service Center]
- [https://web.archive.org/web/20150410130817/http://www.time.ac.cn/center/222.html 短波授时台(Shortwave time signal station)], from the National Time Service Center, Chinese Academy of Sciences https://www.sigidwiki.com/wiki/BPM
{{Time signal stations}}
{{Time signal authorities}}
{{DEFAULTSORT:Bpm (Time Service)}}
Category:Time signal radio stations
Category:Radio stations in China
Category:Shortwave radio stations
{{Measurement-stub}}
{{PRChina-stub}}