BPM (time service)

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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[1] in Pucheng County, Shaanxi at 34°56′55.96″N 109°32′34.93″E / 34.9488778°N 109.5430361°E / 34.9488778; 109.5430361Coordinates: 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,[2] 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:

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[edit]

The BPM time signal, recorded at 2007-01-07 in Beijing

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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 "BPM 标准时间标准频率发波台" ("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.[6]

References[edit]

External links[edit]