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A05-0473-010

Measuring Wall Attenuation

The following method can be used to record the actual RF signal 

attenuation caused by a wall.
1)  In the room containing the wall to be measured, take a 

Link 

Quality

 measurement across an open part of a room. Set up 

the two measuring devices with device #2 nearest to the wall to 

be checked. The dongle should be within range (a few metres) 

of device #1. 

2)  When  satisfied  that  the  measurement  is  stable, 

STOP

 the 

recording and make a note of the attenuation value.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3)  Move device #2 to the other side of the wall, ensure it is in the 

same orientation as before and take a second measurement, 

again noting the attenuation value.

4)  Subtract the first attenuation value from the second attenuation 

value; the result is the attenuation in signal strength resulting 

from the wall. This figure can be used for the wall attenuation in 

the design simulation and should be entered into the 

Edit Wall

 

information box as a 

Custom

 value.

Not able to generate a Network

If the mesh wizard cannot simulate a reliable RF network from the 

data it has, the 

Not possible to create a mesh

 message appears. 

The wizard will give a brief reason for the failure where possible.
The design layout and/or RF criteria will need to be amended to 

realise an acceptable system. Some possible changes that may 

help to find a suitable network include:

 

● Move the gateway to provide wider connectivity with the Agile™ 

RF devices

 

● Re-arrange the Agile™ RF devices to minimise link lengths

 

● Allow longer links or repeaters to be used

 

● Add a repeater (or another Agile™ RF device) to a marginal or 

poor link

 

● Consider if the wall attenuation is set too high and can be 

reduced

How to Resolve a Poor Link Quality in General

Where possible, re-position RF devices to improve the line-of-sight 

between two linked devices which have a poor link signal. If this is 

not possible consider the use of a repeater.

How to Resolve a Poor Link Quality in a Long Corridor

To provide a resilient RF system, the mesh is designed to have 

multiple communication paths back to the gateway. Each device 

must have at least two links to other devices. In a long corridor this 

is sometimes difficult to achieve and some long links may suffer 

from poor signal strength. The solution may be to include one or 

more repeaters in, or adjacent to, the corridor.

How to Resolve a Poor Link Quality through Walls

Walls can significantly reduce RF signal strength and hence the 

link quality between nodes. If the link quality through a wall is poor, 

the solution may be to include one or two repeaters on either or 

both sides of the wall between the nodes in question. (See also 

Measuring Wall Attenuation

.)

In all these suggestions, any Agile™ RF device can be substituted 

to act as a repeater.

Summary of Contents for AGILE

Page 1: ... Series RF devices can transmit and receive they are transceivers When two devices communicate directly with one another they have set up a link the devices at each end of a link are known as nodes A set of devices or nodes communicating together is called a network There can be a wide range of network topologies as shown in the examples following VLF LF MF HF VHF UHF SHF EHF IR Visible light 10kH...

Page 2: ...bout 100m Some common building materials are listed in Table 1 together with typical energy loss figures which can be expected A normal double brick wall for example can reduce a signal s strength by up to a third or more All these factors will contribute to the occurrence in a building of areas of varying signal strengths and reception characteristics Figure 1 Relationship Between Distance and RF...

Page 3: ... and hence each RF link has bi directional communication As every RF device is a transceiver the network can be organized to minimize the use of repeaters This is achieved by allowing each device to receive and re transmit information from its neighbours on to the master device the gateway The Concept of Mesh Hierarchy When there is a direct path between nodes say from device 1 to device 2 the two...

Page 4: ...scans and RF link quality checks The RF energy scan identifies any channel frequencies that are unsuitable and the link quality check ensures that RF communications between nodes is acceptable Why is it Necessary A site RF survey is a critical element in the process of designing and installing a wireless communications network in an office or building The survey will determine the best placement o...

Page 5: ...e a facility diagram or floor plan drawing that depicts the location of walls walkways etc 2 Visual inspection Walk through the facility to verify the accuracy of the facility diagram Add any potential barriers that may affect the propagation of RF signals such as metal racks and partitions items that are not shown on the floor plan 3 Device positions Determine the preliminary location of devices ...

Page 6: ...structions Therefore a system design should take into account obstructions and the level of signal attenuation caused by Wall type and thickness Structural supporting beams Tall metal cabinets such as those that are from floor to ceiling and IT equipment in tall metal enclosures A system design should also consider the site operating conditions like Strong local interferences such as from certain ...

Page 7: ...e system Some possible changes that may help to find a suitable network include Move the gateway to provide wider connectivity with the Agile RF devices Re arrange the Agile RF devices to minimise link lengths Allow longer links or repeaters to be used Add a repeater or another Agile RF device to a marginal or poor link Consider if the wall attenuation is set too high and can be reduced How to Res...

Page 8: ...ic obstructions exist such as near lifts and escalators Do ensure that gateways are accessible for maintenance Do ensure where possible the RF devices are positioned in a line of sight A simple way to check is just to look from a device and see if the other devices are in view Figure 8 Example of Using the Line of Sight Technique In this arrangement the sounder strobe could have been located on th...

Page 9: ...e simulated with a test magnet on an Agile detector see device installation instructions for details and a fault can be created in a system by removing a device from its base Tamper Fault Don ts Don t locate RF devices behind obstructions that can weaken RF signal and cause poor link quality Don t locate Agile RF devices back to back where there is little or no attenuation as 1m separation is requ...

Page 10: ...10 A05 0473 010 SYSTEM SENSOR EUROPE Pittway Tecnologica S r l Via Caboto 19 3 34147 TRIESTE Italy www systemsensoreurope com ...

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