Pages on this website

  • rpi_gpio_ntp
    A PPS driver for Linux systems with GPIO pins (e.g. Raspberry Pi), requiring no kernel patches.
  • Lindy Precision Clock driver
    I'm developing a driver for the NTP daemon reference implementation for the Lindy Precision Clock.
  • lingo
    All that time keeping lingo explained.
  • Jans
    Jans is an unusual NTP server: it can return the systemclock time (and just that) but it can also return blatantly incorrect time.
  • nmea-ntp-dev-4.2.5p158.diff.gz
    Patch against ntp 4.2.5p158 to enable NMEA-PPS.
  • my setup
    My servers are part of the NTP pool project. One can see here what my network consists of.
  • ntp - be on time, always
    For the "deb-a-day"-website I wrote an article trying to convince people to become part of the NTP pool.
  • NTP monitor
    One can let his/hers NTP server be monitored via this page.
  • OmniSync
    OmniSync is a driver for NTPd for people who are firewall-challenged. It allows you to sync against the daytime service (port 13 tcp/udp), time (port 37 tcp/udp), http and https (both also via proxy server).
  • Query NTP server
    At this page one can check if their NTP server is reachable over the internet.
  • ppsldisc.patch.bz2
    Patch to make ppsldisc (Linux PPS patch) behave like a more UNIX-like daemon (forks itself into the background and writes pid to a file).

Links on the net


  • Cesium: also known as atomic clock
  • DCF77: German time signal
  • GPS: Global Positioning System, also emits a time signal
  • HBG: Swiss time signal (uses DCF-77 protocol)
  • MSF: time signal from NPL (UK)
  • NTP: Network Time Protocol, a method for distributing the current time across a network
  • OCXO: a crystal in controlled-temperature environment
  • PPS: Pulse Per Second
  • Rubidium: also known as atomic clock
  • TCXO: a crystal oscillator
  • TDF: French time signal
  • VCO: voltage controlled oscillator
  • WWVB: NIST time signal (US)
Alzatex  *          
American Time & Signal company  *          
Arktime  *  *      *
Beagle software  *  *      *
Beagle software  *          
Brandywine communications *****      *
CNS systems  *  *** *   
Chicago Communications  *  *       
Chronos technology*    *       
ESE precision timing  *  *       
Elproma Electronics***  ** *    
Endrun technologies  *  *       
Franklin instrument company  *         *
Galleon  *  *      *
Gorgy timing  *  **  **  
Gude * *         
Harris/Leitch ** *     *  
Hopf **          
Lindy    *        
Masterclock  *  *   *   
Meinberg **  *       
Moba time *** *       
Noller & Breining software *           
Oscilloquartz* *  ***     
Primex wireless  *  *       
Quancom *           
Sapling Inc  *  *       
Spectracom  *  *****   
Spectratime* *     *    
Spectrum instruments, inc.  *   **     
Symmetricom* *  *       
Time & frequency solutions ** **   *  *
Timetools.co.uk ** **       
Transko      *  * * 
Veracity  *  *       
Wharton precision time systems ** **       
World Time Solutions Limited  *  * * *   


what platform license sync against output
Atomic clock serviceWin32CommercialNTP
Atomic clock time synchronizerWin32FreewareSNTP/RFC868
Atomic time syncWin32Freeware/SharewareNTP
Chronos atomic clock synchronizerWin32?NTP
Clock SyncWin32FreewareNTP
Dimension 4Win32Shareware/CommercialSNTP/RFC868/OtherSNTP/RFC868
Emsa time synchronizerWin32Freeware?
JCOM Clock SynchronizerWin32SharewareNTPNTP?
LS timesyncWin32Freeware
NTP digital wall clockWin32FreewareNTP
Network time server/clientWin32CommercialNTP
On-Time atomic clock syncWin32SharewareNTP
PTP daemonPosixBSDPTP (IEEE 1588)PTP (IEEE 1588)
SP TimeSyncWin32Freeware/CommercialNTP
Simple network time syncPosixBSDSNTS
TimeTools GPS ClockWin32FreewareGPS


  • Linux PPS
    Rodolfo Giometti is developing a PPS implementation for the Linux kernel.
  • atomic-clocks.com
    This company has atomic clock watches/clocks/etc. Only for US!
  • how atomic clocks work
    Web-page describing how atomic clocks work.
  • radio clocks for pcs
    Building your own radio-clock. Describes hardware for a DCF-77 as well as an MSF receiver.
  • RFC868
    Describes the 'time'-protocol which can be retrieved via port 37 (TCP and UDP).
  • RFC1305
    Describes the 'network time protocol' (port 123 UDP). This one is preferred over 'time' (port 37) as it also handles delays and jitters correctly.
  • Time @ wikipedia
    Document in Wikipedia which describes time.
  • PIC NTP server
    A microcontroller based NTP server, synchronized to a GPS receiver.
  • IEEE 1588
    A precision clock synchronization protocol for networked measurement and control systems.