RF Pulse Bridge

An RF Pulse Bridge conveys one or more pulse counts from one point to another using a Radio Frequency link.  Typically this will be from a meter or transducer to an SHM data logger. 

The use of an RF Pulse Bridge avoids using a direct cable connection in cases where this would be inconvenient or expensive.  The most typical scenario is taking a pulse from a water meter situated in a pit outside the main building to a data logger inside the building.

Even though the transmitter is below ground beneath a metal manhole cover, it is possible to receive a signal at distances up to 100 metres away, or further if a repeater is used.

If several pulse bridges are required, it is generally more cost-effective to use the RL32 Radio Frequency logger which provides up to 24 pulse-bridge channels and has a single receiver.

Transmitter This picture shows the totally encapsulated blue "lollipop transmitter" inside a meter pit and connected to a water meter fitted with a pulse output probe. The transmitter has in integral battery with a life of 7 to 10 years.  It transmits the pulse count every few minutes. Certified intrinsically-safe transmitters are available that can be used to form a pulse bridge for gas meters, avoiding the use of an isolating relay and associated cabling.

Receiver This picture shows the receiver unit (upper box) connected to the UL8 logger below (the blue box). In this case the receiver is connected to an external aerial, although  a simple  'whip' antenna is all that is normally required. The pulse receiver is also available like the transmitter in the totally encapsulated "lollipop" format. The receiver is either powered from a separate DC supply or from the logger itself.