BSF (time service)
BSF is the callsign of the time signal transmitter for Taiwan, which transmits time information on 77.5 kHz in the longwave range, and 5 MHz & 15 MHz in the shortwave range from Chung-Li. The transmitter, which uses a T-antenna is situated at 25°0′20″N 121°21′54″E / 25.00556°N 121.36500°E / 25.00556; 121.36500 (BSF Time Signal Transmitter).
Longwave transmitter
The longwave transmitter of the station uses 1 kW of power, achieving an effective radiated power of 460 W. 120 bits of information are transmitted each minute using amplitude-shift keying, whereby five basic states can be transmitted, encoding either pair of bits or a special synchronization mark:
- 200 ms low and 800 ms high means 00
- 400 ms low and 600 ms high means 01
- 600 ms low and 400 ms high means 11
- 800 ms low and 200 ms high means 10
- 1000 ms high means SYNCH
Shortwave transmitter
The shortwave transmitter on 5 MHz operates continuously, while that on 15 MHz has an interruption between 35 and 40 minutes after the hour. The shortwave transmitters transmit during the five-minute intervals, with odd-count second pulses of 5 ms duration and 1 kHz modulation, and even-count second pulses of 5 ms without modulation. For 40 ms before and after the pulse, there is no modulation with the 1 kHz tone. Minute pulses have a length of 300 ms.
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