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.
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TransmitterThis 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. |
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ReceiverThis 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. |