Support for most of the commonly available radio and modem clocks is
included in the default configuration of the NTP daemon for Unix
xntpd. Individual clocks can be activated by configuration
file commands, specifically the server and
fudge commands described in the xntpd program manual page. The
following discussion presents Information on how to select and configure
the device drivers in a running Unix system.
Radio and modem clocks by convention have addresses in the form
127.127.t.u, where t is the clock type and
u is a unit number in the range 0-3 used to distinguish
multiple instances of clocks of the same type. Most of these clocks
require support in the form of a serial port or special bus peripheral.
The particular device is normally specified by adding a soft link
/dev/device%d to the particular hardware device involved,
where %d correspond to the unit number above.
Following is a list showing the type and title of each driver currently implemented. Click on a selected type for specific description and configuration documentation, including the clock address, reference ID, driver ID, serial port device name and speed, and features (line disciplines, etc.). For those drivers without specific documentation, please contact the author listed in the copyright page.
Type 1 Local Clock Driver
Type 2 Trak 8820 GPS Receiver
Type 3 PSTI/Traconex 1020 WWV/WWVH
Receiver
Type 4 Spectracom 8170 and Netclock/2
WWVB Receivers
Type 5 TrueTime GPS/GOES/OMEGA Receivers
Type 6 IRIG Audio Decoder
Type 7 Scratchbuilt CHU Receiver
Type 8 Generic Reference Driver
Type 9 Magnavox MX4200 GPS Receiver
Type 10 Austron 2200A/2201A GPS
Receivers
Type 11 * (old TrueTime OMEGA Receiver)
Type 12 KSI/Odetics TPRO/S IRIG
Interface
Type 13 Leitch CSD 5300 Master Clock Controller
Type 14 EES M201 MSF Receiver
Type 15 * (old TrueTime TM-TMD GPS
Receiver)
Type 16 Bancomm GPS/IRIG Receiver
Type 17 Datum Precision Time System
Type 18 NIST Modem Time Service
Type 19 Heath WWV/WWVH Receiver
Type 20 Generic NMEA GPS Receiver
Type 21 Motorola GPS Receiver
Type 22 PPS Clock Discipline
Type 23 PTB Modem Time Service
Type 24 USNO Modem Time Service
Type 25 * (old TrueTime generic)
Type 26 Hewlett Packard 58503A GPS
Receiver
* All TrueTime receivers are now supported by one driver, type 5. Types 11, 15 and 25 will be retained only for a limited time and may be reassigned in future.
Additional Information
Mitigation Rules and the prefer
Keyword
Debugging Hints for Reference Clock
Drivers
Line Disciplines and Streams Drivers
Pulse-per-second (PPS) Signal Interfacing
How To Write a Reference Clock Driver