电波对时
来自Jack's Lab
目录 |
1 Station
1.1 China
Freq: 68.5KHz
Code: BPC
Ops: NTSC
https://en.wikipedia.org/wiki/BPC_(time_signal)
1.2 Japan
Freq: 40KHz/60KHz
Code: JJY
Ops: NICT
1.3 USA
Freq: 60KHz
Code: WWVB
Ops: NIST
- https://en.wikipedia.org/wiki/WWVB
- https://www.nist.gov/pml/time-and-frequency-division/radio-stations/wwvb
1.4 England
Freq: 60KHz
Code: MSF
Ops: NPL
- https://en.wikipedia.org/wiki/Time_from_NPL
- http://www.npl.co.uk/science-technology/time-frequency/products-and-services/time/msf-radio-time-signal
1.5 German
Freq: 77.5KHz
Code: DCF77
Ops: PTB
- https://www.ptb.de/cms/en/ptb/fachabteilungen/abt4/fb-44/ag-442/dissemination-of-legal-time/dcf77.html
- https://en.wikipedia.org/wiki/DCF77
- https://www.eecis.udel.edu/~mills/ntp/dcf77.html
1.6 Swiss
Freq: 75KHz
Code: HBG
Ops: METAS
2 Format
2.1 BPC
载波 68.5KHz,脉宽调制 (Pulse-Width Modulation,PWM),码率 1 Hz
每个编码脉冲宽度为 0.1s,0.2s,0.3s 或 0.4s,分别代表四进制的 0,1,2,3。一串四进制的数字是由播发时刻的秒、时、分、星期、日、月、年插入几个校验位组成,长度为 20s
2.2 JJY
载波 40KHz 和 60KHz,脉宽调制 (Pulse-Width Modulation,PWM),格式类似美国 WWVB 码: