Wireless Clocks Explained
The Bodet DHF wireless clocks and wireless bell systems can synchronise clock networks in one or several buildings without any cables.
A secured time message is transmitted from the Master Clock to the slave clocks via HF radio waves. Slave clocks pick up the message and automatically synchronise time. The radio frequency is part of the licence free ISM band (Industrial Scientific and Medical) according to ETS 300-220 European standard.
Reduce Maintenance (Automatic GMT/BST changeover).
Suitable for existing buildings (No cabling).
Easy installation (No business interruption).
Always on time (Radio or GPS synchronised system).
Industrial or public premise refurbishment.
Multi site installations.
University campus, major production sites, locations separated by roads or highways.
Wired or POE Clocks
A master clock synchronises the slave clocks and keeps precise and accurate time to all clocks. The master clock is usually connected to a Radio or a GPS antenna. In a wired network, slave clocks can be synchronised either by current impulses or by a digital signal coming from the master clock.
Time Distribution: Impulse
A signal is sent through polarised impulses every minute, half minute or second.
Time Distribution: Digital AFNOR
The AFNOR (Time Code) signal provides an accurate and secured time transmission. This type of distribution is mainly used in large installations (Airports, Railways) with a long length distance between the Slave Clocks.
Advantage : Perfect for very large installations including digital clocks in new buildings.
Time Distribution: NTP
NTP (Network Time Protocol) is a protocol designed to synchronise clocks or equipment (computers…) over a network.
For simplicity of operation, the clocks can be Power-over-Ethernet (PoE) devices. No mains socket is required, the device is powered from the network jack plug. Installation is therefore very straightforward, and the units can be easily moved, making it a very portable system. Analogue or digital clocks utilise ntp over ethernet to continuously display an accurate synchronised time.
Advantage : Permits the automatic synchronisation of all equipment connected. The protocol is used worldwide.
The main transmitters in europe are located in: United Kingdom (MSF), France (France Inter) and Germany (DCF). Slave clock receives the time message, checks it, and compares it to its internal clock. If there is a difference, it automatically resets the time. The clock operates on the internal time base in case of radio signal interruption. The radio synchronisation provides absolute accuracy and automatic summer/winter changeovers. Today, most of the clock systems are equipped with a radio antenna.
All over the world, time synchronisation can be ensured via a network of 24 satellites part of the GPS system. The GPS antenna receives the time message every second, decodes it and sends it to the master clock.