This type of system is frequently installed in environments with very high-tech requirement on time distribution, e.g. railways and airports.

This system is characterized by serial time code BCD (Binary Coded Decimal) control and operation of connected clocks (both analogue and digital) distributed from a Master Clock or Time Central with an IRIG-B output. The time code is modulated on a 1 kHz signal. Each movement in connected clocks has its own microprocessor to receive the time code, detecting the position of the hands and thereafter automatically set the hands to correct time.

Westerstrand clocks for IRIG-B system require mains supply 230V AC and are connected to IRIG-B code using 2-polar screw terminal. When connected analogue clocks have received and accepted the IRIG-B signal, they will automatically step forward to correct time by rapid impulses. Digital clocks are automatically set to correct time within 2 minutes after connection. In case the IRIG-B would disappear, a built-in quartz crystal will take over control of correct time.

In case of power failure the clocks are temporarily stopped. When power returns the hands (analogue and clocks) will automatically, and rapidly, be set to 12-position and thereafter to correct time. With the option running reserve, the clocks will continue to work during the power failure for 12 hours. Digital clocks are automatically set to correct time within 2 minutes after power has returned.