On Sun, 15 Oct 2006 11:28:09 GMT, Torsten Krieger wrote: > Hi Uwe, > > I made a small c program which reads the serial port /dev/refclock-0 > character by character, ntpd switched off. Shall I see one character by > second (second = 1/60 minute) 0xf0 for low bit and 0x00 for high bit? If > this should be the case then something went wrong with my serial interface. > > Ciao, > Torsten > > Uwe wrote: >>http://www.eecis.udel.edu/~mills/ntp/dcf77.html >> >>The DCF Signals is 1 pulse every 1 second. the 59th pulse is omitted to >>mark the minute transition. >>AAdditonal information is coded into the pulselength of the second pulses. >>0.1 sec for a low bit, 0.2sec for a high bit. >> >>on a 50Baud (0.02s/bit) serial line with inverted sense this is received as >> >>HHHHLLLLLHHHHHHHH S=StartBit, s=StopBit(s) >>____S01234567s____ 0xf0 for a low bit >> >>and >> >>HHHHLLLLLLLLLHHH >>____S01234567s____ 0x00 for a high bit >> >>uwe > I dont think its that simple in practice. The DCF receivers I have used have some large jitter on both start and length of pulse. Add to that noise impulses. Try and print the bits and figure out what signal you get. /hjj
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