Regardless the method for synchronization, clocks can be operated stand alone or in local networks.

A centralized time network has the advantage of offering many functions. Depending on the performance of the central time base, which is the heart of a time network, many time related controls can be handled, e.g. in building management, industrial processes, public communication and transports. In a time network it is also possible to supervise what is displayed on connected clocks, so that misinformation of time can be eliminated.

Signals used for the control of clocks and other connected units in a network are of two types. Either they are just a polarized reversing electric impulse or a coded signal including time information.

In an impulse operated system a master - Master Clock or Time Central – sends polarized reversing impulses. The frequency for sending impulses can vary. If the clocks display seconds then the impulses have to be sent every second.

A coded time signal includes data of time and date. There is no universal definition for the format of a coded time signal. A common format in time measuring is the IRIG-B code family. This standard (includes several versions) was initially set to facilitate interchange of data between various test laboratories which require time synchronization. IRIG-B is a serial time code BCD (Binary Coded Decimal).

The DCF-77 signal is the most used signal for time synchronisation by radio. DCF-format could also be used in wire-bound systems, e.g.Westerstrand TC-system.

There are also code formats developed for a specific industries or businesses. An example of that is the SMPTE/EBU code used in radio- and television companies and entertainment industry.

Time code messages can also be integrated into modern bus-technology, such as LonWorks, Profibus, etc.

Some manufacturers of time equipment have developed their own format for time distribution, which of course limits the use of other manufacturers equipment in such nets.