table of contents
RADIOCLKD(1) | Network Time Protocol Daemon | RADIOCLKD(1) |
NAME¶
radioclkd - decode time from radio clock(s) attached to serial portSYNOPSIS¶
radioclkd [ -tphv ] deviceDESCRIPTION¶
radioclkd is a simple daemon that decodes the time from a radio clock device attached to the DCD and/or CTS and/or DSR status lines of serial port of a computer. It is able to decode the DCF77, MSF and WWVB time signals. The received time is then sent to ntpd using the shared memory reference clock driver. The type of time signal being received is automatically determined. If you have problems getting the program to work using interrupts, the following command is known to help in many instances. If this fails you can always fall back to the polling method.- stty crtscts < /dev/ttyS0
OPTIONS¶
- -p, --poll
- Poll the serial port for changes of status in the DCD, CTS and DSR lines rather than use interrupts
- -t, --test
- Enter test mode printing the length of each pulse and the decoded time at the end of each minute on stdout. The time is not sent to ntpd using the shared memory reference clock driver in this mode.
- -h, --help
- Print a short synopsis of the command line arguments.
- -v, --version
- Print the version number and then exit.
CONFIGURATION¶
Configuration is very simple. Use server 127.127.28.0 in your ntp.conf file for a clock attached to the DCD line, server 127.127.28.1 for a clock attached to the CTS line, and server 127.127.28.2 for a clock attached to the DSR line. You will also want to use a fudge line on the server to change the displayed refid.CALIBRATION¶
Due to delays in the propogation of the radio signal, it's processing by the receiver board and the latency of the operating system the time decoded by the receiver will be slightly offset from actual UTC. Typically this delay will be less than 20ms, so unless you are very fussy about the time, or are using more than one time source, such as a GPS unit, other radio clock or NTP server on the internet you can ignore this section.statsdir /var/log/ntpstats/
statistics loopstats peerstats clockstats
filegen peerstats file peerstats type day enable
IN USE¶
The version of ntpd that comes with most Linux distributions does not have the shared memory reference clock driver compiled in by default. This can be identified by checking the logs after ntpd is started. If the shared memory reference clock driver is not compiled in then the logs will contain warnings about the reference clock driver not being recognized. To compile ntpd with the shared memory reference clock driver you must specify the --enable-SHM option when running configure.BUGS¶
If you are running a kernel with the PPS kit and have a clock attached to the DCD line you may experience lockups. If you encounter this problem the currently recomended solution is to move the clock to either the CTS or DSR lines.AUTHOR¶
This program was written by Jonathan Buzzard <jonathan@buzzard.org.uk> and may be freely distributed under the terms of the GNU General Public License. There is ABSOLUTELY NO WARRANTY for this program.19 Jan 2003 | Version 1.0 |