System Sensor AGILE Application And Installation Manuallines
CONTENTS
Radio Basics.................................1
The RF Waveband 1
The RF Network 1
RF Signal Characteristics 1
RF Signal Attenuation 2
Agile™ 200 Series RF Fire System ............... 3
The Concept of Mesh Hierarchy 3
Network Synchronisation 4
The Back-up Node 4
Site Survey ..................................4
What is a Site Survey 4
Why is it Necessary 4
How to Plan a Site Survey 4
What to Take to a Site Survey 5
Summary of Basic RF Site Survey Principles 5
Some Guidelines for using the Agile™ 200 Series
Radio System ................................6
Agile™ System Coverage 6
Measuring Wall Attenuation 7
Not Able to Generate a Network 7
How to Resolve a Poor Link Quality 7
RF Do’s and Don’ts 8
Do’s 8
Don’ts 9
AGILE™ RADIO FIRE DETECTION SYSTEM
APPLICATION and INSTALLATION GUIDELINES
RF BASICS
The RF Waveband
Radio frequency (RF) devices use radio waves to communicate
(transmit and receive data) in the form of coded radio signals. The
RF waveband (part of the electromagnetic spectrum) ranges from
a few kHz to hundreds of GHz and can be divided up into different
sections, with different radio characteristics and capabilities.
The Agile™ 200 Series RF re system uses a frequency range
based around 868MHz in the UHF region (the lower end of
microwaves); that is a wavelength of 346mm.
Short-range, low-power RF Systems are becoming more popular
for a wide range of applications; within re and security products
they are often used in temporary installations or situations where
building work and unsightly cabling cannot be tolerated.
The RF Network
Agile™ 200 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
10kHz
100kHz
1MHz
10MHz
100MHz
1GHz
10GHz
100GHz
1000GHz
System Sensor 200 Series RF
THF
Ring
Star
Fully
Connected
Line
Tree
Bus
Mesh
RF Signal Characteristics
Fundamentally radio signals, like light, travel in straight lines. And
in the same way as light they can be affected by objects in their
path. Forming part of the electromagnetic energy spectrum, they
are capable of transmission through some materials, absorption by
others and can be reected, refracted and diffracted. The effects
on radio waves caused by different materials are dependent upon
the material’s properties.
Metallic surfaces are excellent reectors of radio frequency
(RF) energy; water and wet areas may also be good reectors.
Refraction occurs when electromagnetic waves pass across
a boundary between materials of different densities (refractive
index) and diffraction can occur when signals pass close to large,
particularly sharp, objects. Attenuation in different materials
(resulting from energy absorption and high frequency scattering)
is caused by the material’s molecular characteristics, structure and
resonances at different wavelengths.
In an open space, the power reduction down a signal path is
proportional to the square of the distance from the transmitter (see
Figure 1 following).
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1
1
2
2
d
2xd
RF Signal Attenuation
In addition to this square law attenuation, signal strengths inside a
building will also vary from place to place owing to destructive and
constructive interference caused by signals arriving with different
phases, resulting from different path lengths (see Figure 2).
The Agile™ 200 Series RF devices have a typical transmission
range in free air of up to 500m, but within an ofce or factory
environment, signals can come into contact with many objects in
a range of materials such as ceilings, oors and walls at different
angles, desks, ling cabinets and a variety of plant and machinery.
There are numerous opportunities for reection, refraction and
absorption and all these things will probably reduce the effective
range, even in an open plan environment, to not much more than
about 100m.
Some common building materials are listed in Table 1 together
with typical energy loss gures 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-Power
SURFACE AT DISTANCE 2d
SURFACE AT DISTANCE d
SURFACE MEASURES 1M2 AT DISTANCE d
SURFACE MEASURES 4M2 AT DISTANCE 2d
WHEN THE DISTANCE IS DOUBLED, THE FIELD
STRENGTH IS REDUCED BY A FACTOR OF 4
RADIO GATEWAY
Figure 2: Different RF Signal Paths
Table 1: Energy Loss with Different Materials
Designing and installing an RF system in areas with large radio
eld absorption, e.g. with metallic lattice partitions, large metal
vessels or with tall metallic storage racks may be very challenging.
Material Type Energy Loss
Wood and plasterboard 0 – 10%
Solid brick 5 – 35%
Steel reinforced concrete 30 – 90%
Metal plates, under oor heating 90 – 100%
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AGILE™ RF FIRE SYSTEM
The Agile™ 200 Series RF re system is designed for use with
compatible intelligent re systems using the System Sensor
200/500 Series CLIP, Enhanced and Advanced communication
protocols. Devices signalling from the radio domain are translated
by the RF gateway into addressable loop communication signals
recognized by the Control and Indicating Equipment (CIE). Each
device has its own physical address on the loop, selected using
two rotary switches, which can be manually set in a range between
1 and 99 or 1 and 159 depending on the loop protocol used by the
panel.
The system architecture can be characterised as shown in Figure 3
following.
Figure 3: System Overview
WIRED FIRE SYSTEM
WIRELESS FIRE SYSTEM
CIE
DETECTOR
SOUNDER /
STROBE
GATEWAY
REPEATER
WIRELESS
DETECTOR
WIRELESS CALL
POINT
LAPTOP / PC
RUNNING
AgileIQ™
USB
INTERFACE
(DONGLE)
MODULE CALL POINT
The red and black lines show the wired loop; the dotted
blue lines represent the RF communication. A PC has
the ability to communicate with all the wireless devices
using a special software application (AgileIQ™) and
USB transmit/receive interface dongle.
Figure 4: Mesh Hierarchy
The Agile™ RF Mesh Network
When two devices in a network can communicate directly, they
are said to have a link. The devices at each end of a link are
known as nodes and a network is made up of a set of nodes and
links. For the 200 Series RF system, each RF device can receive
and transmit wireless information and hence each RF link has bidirectional 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 nodes are linked. Within the mesh there
are the concepts of ‘parents’ and ‘children’, and ‘ancestors’ and
‘descendants’, moving in the direction from the gateway to the
mesh boundary. So, whilst links have bi-directional communication,
there is also a concept of link directionality with respect to the order
or ranking of each of the devices. This is why links are shown with
directional arrows, establishing the hierarchy of the nodes.
In the Agile™ RF system, each node can have up to 6 active links
with its neighbours; 2 links going toward the gateway (one from
each of its 2 parents) and up to 4 links going toward the network
boundaries (i.e.to 4 children). A gateway is a special RF node and
can have up to 32 links.
Node
Directional
Link
Parent
Ancestor
Child
Descendant
4
1
3
5
2
6
Direction of Mesh Boundary
In general, to satisfy the Agile™ mesh protocol criteria in terms
of hierarchy and timings, all nodes should be descendents of the
gateway, (i.e. there must be a chain of primary links to/from the
gateway) and each device will have one primary link to a parent
and one secondary link to its other parent. All links from a gateway
will be primary links.
Note the unique and important Back-up Node #2; this has only one
parent – the gateway. Its importance in the network is described
below.
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