BPM time signal in waterfall

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 34°56′55.96″N 109°32′34.93″E / 34.9488778°N 109.5430361°E / 34.9488778; 109.5430361, roughly 70 km northeast of Lintong,[1] 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:[2]

MHzUTCCST
2.57:30-1:0015:30-9:00
50:00-24:000:00-24:00
100:00-24:000:00-24:00
151:00-9:009:00-17:00

Transmission format

BPM transmits different signals on a half-hour schedule, modulated with 1 kHz audio tones to provide second and minute ticks:

BPM transmission schedule[2][3]
MinuteDurationTransmission
003010UTC: 10 ms second ticks, 300 ms minute ticks, in advance by 20 ms.[4]
BCD time code on 100 Hz sub-carrier.[5]
10405Carrier (no time code)
154510UTC: 10 ms second ticks, 300 ms minute ticks, in advance by 20 ms.[4]
BCD time code on 100 Hz sub-carrier.[5]
25554UT1: 100 ms second ticks, 300 ms minute ticks.
29591Station 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.[6]

BPM time code[5]
BitWeightMeaningEx BitWeightMeaningEx BitWeightMeaningEx
:00No 125 Hz (minute mark) :201Day of month
Example: 28		0 :401Year
Example: 06		0
:011Minutes
Example: 23		1 :2120 :4121
:0221 :2240 :4241
:0340 :2381 :4380
:0480 :2400 :4400
:0500 :25100 :45100
:06100 :26201 :46200
:07201 :270Reserved, always 0.0 :47400
:08400 :2800 :48800
:09P1MarkerM :29P3MarkerM :49P5MarkerM
:101Hours
Example: 19		1 :301Month
Example: 02		0 :50+DUT1 sign (1=positive)1
:1120 :3121 :510.1DUT1 magnitude (0 to 0.9 s)
DUT1 = UT1−UTC
Example: +0.5 s		1
:1240 :3240 :520.20
:1381 :3380 :530.41
:1400 :3400 :540.80
:15101 :35100 :550Reserved, always 0.0
:16200 :360Reserved, always 0.0 :5600
:170Reserved, always 0.0 :3700 :57LSLeap second0
:1800 :3800 :580Reserved, always 0.0
:19P2MarkerM :39P4MarkerM :59P0MarkerM

References

  1. ↑ "National Time Service Center: Facilities".
  2. 1 2 "短波授时台". National Time Service Center. Archived from the original on 2015-04-10.
  3. ↑ Marco1971 (2007-01-23). "Re: A question about Wave Ceptor frequency reception". Retrieved 2011-04-29.{{cite web}}: CS1 maint: numeric names: authors list (link)
  4. 1 2 BIPM Annual Report on Time Activities – Time Signals, retrieved 2011 September 12.
  5. 1 2 3 Dissemination scheme of BPM shortwave time code time-service (in chinese), retrieved 2018 August 20.
  6. ↑ "HF (SW) Radio - Time NZ & A". Archived from the original on 2012-12-30. Retrieved 2011-04-25.


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