overview what is wireless? how does it work? problems and limitations mounting locations paradox...
TRANSCRIPT
Overview
• What is Wireless?
• How Does it Work?
• Problems and Limitations
• Mounting Locations
• Paradox Wireless Technology
• Paradox Wireless Products
What is Wireless?
• A term used to describe telecommunications in which electromagnetic waves, rather than some form of wire, carry signals over the communication path
• Most wireless products use Radio Frequency (RF) signals to communicate
What is Wireless?
• RF waves occupy a large portion of the electromagnetic spectrum – from 9kHz to 300GHz
What is Wireless?
• The RF spectrum is divided into 8 bands• Paradox wireless products are in UHF band
Paradox Products
* Often referred to as the microwave spectrum.
10 mm – 1 mm30 GHz – 300 GHzEHFExtremely High Frequency*
100 mm – 10 mm3 GHz – 30 GHzSHFSuper High Frequency*
1 m – 100 mm300 MHz – 3 GHzUHFUltra High Frequency
10 m – 1 m30 MHz – 300 MHzVHFVery High Frequency
100 m – 10 m3 MHz – 30 MHzHFHigh Frequency
1 km – 100 m300 kHz – 3 MHzMFMedium Frequency
10 km – 1 km30 kHz – 300 kHzLFLow Frequency
33 km – 10 km9 kHz – 30 kHzVLFVery Low Frequency
Free-space WavelengthsFrequenciesAbbreviationDesignation
How Does it Work?
• A wireless system is made up of a receiver (Rx) and transmitters (Tx)
• When an RF current (AC) is supplied to an antenna, it generates an electromagnetic field (RF field) that is suitable for wireless broadcasting and/or communication
Example
• Example: A motion detector (Tx) has an open zone
– Detector (Tx) converts the digital signal (binary) into an RF signal
Example
Example
– The RF signal is sent from the detector to the receiver via the antenna
Example
– The receiver converts the RF signal back to a digital signal
Example
– The digital signal is then interpreted by either an outside source (i.e. control panel) or within the receiver itself (i.e. Magellan)
Problems and Limitations
• The main obstacle to wireless systems is interference, which can cause minor annoyances or prevent the system from functioning altogether
• Interference simplified:– Imagine you are in a room in front of 1000 people, who are all
talking at the same time, and you try to listen to only one person in the crowd. During this time, a police car goes by with its siren on and a dog is barking. Each person, the police siren and the dog represent different signals at different frequencies.
– The noisy people, police siren and barking dog are all sources of interference
Problems and Limitations
• Types of Interference– Radio Frequency (RF) Interference
• Multipath Interference
– Electrical Interference– Intermodulation
• RF Reflection and Attenuation
RF Interference
• RF Interference– Defined as an undesired signal received by a wireless
device that prevents it from receiving clear signal reception
– Any device that generates RF as part of its functionality can also cause RFI
– The interfering signal does not have to be on the same frequency. Signals that are near the receiver’s frequency can also interfere with the receiver
RF Interference
• Possible sources of RFI:– AM, short-wave, FM and TV broadcast transmitters– Ham radio and CB transmitters– Remote controls– Wireless phones– Cellular phones
RF Interference
– Commercial taxi, police and aircraft radios– Microwave ovens– Motion sensors– Radar systems– And many more medical and industrial devices
Multipath Interference
• Multipath Interference– A form of RF interference– Occurs when more than one RF wave from the same
transmitter reaches the receiver
Multipath Interference
– The RF signal moves between the transmitting and receiving antenna in the most direct path (A), but it also reflects (B) off metallic and other surfaces
Multipath Interference
– When the different RF waves combine they cause distortion to the desired RF wave, which makes the signal difficult to decode
Multipath Interference
– In extreme situations, the reflected RF wave (B) inverts and cancels out the direct path RF wave (A)
Multipath Interference
– To remedy this, simply move the transmitter or receiver a few inches
Electrical Interference
• Electrical Interference– Caused by the unintentional generation of RF due to
an electrical spark, arc or discharge– Any wiring connected to the spark source conducts
the RF and acts as a transmitting antenna– As a general rule, the noisier an electrical device is
the potential it has of generating RF noise
Electrical Interference
• Three types of electrical interference– RF noise from electrical equipment– RF noise generated by electronic devices– Interference from natural sources such as lightning
Electrical Interference
• Possible sources of electrical interference:– TV or computer cathode ray tube (CRT) displays– Electric welders– Air conditioners– Brush-type motors
Electrical Interference
– Relays and switches of all kinds– Arcing and corona discharge in power line insulators– Malfunctioning flourescent/neon lighting and
automobile spark plugs– Light dimmers
Intermodulation
• Intermodulation– Occurs when a strong signal (i.e. communications
tower), whose frequency is generally not near that of the wireless receiver, overloads some circuit in the receiver
– As a result, the circuit generates harmonics of the strong signal, which then combine in the receiver to create a new frequency
Intermodulation
– The newly created frequency, called an Intermodulation Product, interferes with the wireless system in much the same way as other sources of interference
– For example, mounting a transmitter too close to a receiver can cause intermodulation. The signal from the transmitter is too strong due to its proximity to the receiver
RF Reflection and Attenuation
• RF Reflection and Attenuation– Reflection: RF signals bounce off a reflective surface
such as a wall or the ground– Attenuation: When RF signals pass through solid
objects, some of the signal power is absorbed. This loss of RF energy is called Attenuation, which varies depending on the structure of the object
RF Reflection and Attenuation
– An installation site’s physical construction and the obstacles on the site affect RF signals
– Walls, doors, floors, elevator shafts, people and other obstacles offer varying degrees of attenuation and reflection
– This causes the RF radiation pattern to be irregular and unpredictable
RF Reflection and Attenuation
• When an RF wave meets an obstacle, one of the following three phenomena occur:– Reflection
• Reflection from walls, ceilings and floor surfaces can be partial or complete and cause multipath interference
RF Reflection and Attenuation
– Refraction• Occurs when an RF wave crosses a boundary from one
medium to another (i.e. from air to water). A wave entering a medium at an angle will change direction
RF Reflection and Attenuation
– Diffraction: It is the bending of RF waves around an object’s edge, such as a sharp corner or opening
RF Reflection and Attenuation
• Objects that reflect and attenuate RF signals include:– Metal objects– Objects with metal in them– Ground– Circuit breaker boxes– Trees: RF energy loss depends on the size and type
of tree. Large trees with dense foliage create greater loss
RF Reflection and Attenuation
– Walls: Interior walls create less RF energy loss and exterior walls, especially those with stucco, create greater loss
– Floors: Wood floors create less RF energy loss and concrete and steel floors create greater loss
– Mirrored walls have very high RF energy loss because the reflective coating is conductive
Mounting Locations
• Mounting locations affect the overall performance of the wireless system
• In order to ensure the best possible signal reception, the following list of criteria should be respected whenever possible
Mounting Locations
• Select an installation site that is free of obstacles that reflect and absorb RF signals (RF reflection and attenuation), and avoid installation near or in the path of strong RF fields (interference)– One of the most basic obstacles is the ground and its
relation to the receiver. The ground works as an RF noise generator, and also mirrors RF signals and sometimes even absorbs them
Mounting Locations
– Avoid mounting the receiver in the basement as the range of the receiver is reduced when mounted below ground level
– If it is absolutely necessary that the receiver be mounted in the basement, ensure that it is mounted as high and as close to the underside of the first floor as possible
Mounting Locations
• Select a site that is not susceptible to drastic temperature changes– Mounting the receiver or transmitter in an area with
drastic temperature changes can cause condensation and moisture to collect in the receiver or transmitter
– Common problem areas include:• Heater air duct• Exterior doors• Refrigerators and freezers• Garage
Mounting Locations
• Mount the wireless receiver as high and as central as possible to the proposed placement of the transmitters– Ideally, the perfect antenna spreads its signal like a
perfectly round circle. However, because of the transmitter’s physical construction (i.e. PCB, battery) it is more like a figure 8.
Mounting Locations
– The “dead spot”, or area where the RF signal is weak or non-existent, varies from one transmitter to the next
– Mounting the receiver as central as possible to the transmitters will help in avoiding the “dead spots”
Mounting Locations
• Do not mount the transmitters too close to each other. Do not mount the transmitters too far or too close to the receiver– When RF devices are too close, strong RF signals
can cause the devices to malfunction (Intermodulation)
– When a transmitter is mounted too far from the receiver, the RF signal is too weak to communicate effectively or at all
Mounting Locations
– As a general rule, when installing transmitters ensure that there is at least 30cm (1ft) between each transmitter, and at least 1.5m (5ft) between each transmitter and the receiver
– The maximum distance that a transmitter can be from the receiver is dependant on the transmitter’s transmission range
Paradox Wireless Technology
• Paradox wireless products– 433MHz and 868MHz– UHF band of the RF spectrum
Paradox Wireless Technology
• Reliable Data Transmission and Reception– Information is sent and received consistently and
without error– Cyclic Redundancy Check (CRC) Algorithm
• An error correction code that is used to catch errors in data• Verifies the integrity of the data to ensure that the signal
comes from the correct source
– Every message that is sent by a transmitter to the receiver is sent 8 times for increased reliability in noisy environments
• Only 1 of the 8 messages must be correct for the receiver to process the message
Paradox Wireless Technology
• Receiver Sensitivity– A receiver’s sensitivity is the ability to discriminate
between a good signal and the noise generated by the environment and the receiver circuit itself
– Low threshold for increased sensitivity• Can distinguish between the desired signal and noise that is
very close to the desired signal’s frequency
– A low-noise amplifier raises the power level of the received RF signal for increased sensitivity
– CRC algorithm checks for any errors in the data
Paradox Wireless Technology
– 4-Step Noise Filtering removes as much noise from the received signal as possible
• Surface Acoustic Wave (SAW) filter• Ceramic filter• Low-pass filter• Software filter
Paradox Wireless Technology
• Transmitters– Use a quartz crystal oscillator to stabilize the output
frequency and ensure that the signal frequency is always in the band of the receiver
Paradox Wireless Technology
• Antennas– Tuned specifically for 433MHz or 868MHz
• Antenna receives the strongest signals at 433MHz or 868MHz. Other signals at different frequencies are received but are weaker
– Receiver antenna tuned to receive the desired signal at its highest power level (1/4 wavelength)
Paradox Wireless Technology
– Spectra 1759MG• One 1/4-wavelength
ground plane monopole
Paradox Wireless Technology
– MG-RCV3• One 1/4-wavelength
monopole
Paradox Wireless Technology
– Magellan• 433MHz: One 1/4-wavelength
folded monopole
• 868Mhz: One helical
antenna
Paradox Wireless Technology
– Transmitters• One helical
• Except remotecontrols andMG-DCT2: One PCB-Printed
antenna
Paradox Wireless Technology
• Installation features– Save time when selecting mounting locations for the
receiver and transmitters– Signal Strength Test
• Used to verify the signal strength of each transmitter
– Noise Level Test• Used to verify the environment noise surrounding the
receiver
• Supervision features– Low-battery– Tamper– Check-in
Paradox Wireless Products
• Paradox wireless products are available in 433MHz and 868MHz
Paradox Wireless Products
• Spectra 1759MG– 15-zone wireless control
panel– Built-in wireless
receiver
Paradox Wireless Products
• Magellan (MG-6060)– Magellan all-in-one wireless console
Paradox Wireless Products
• MG-RCV3– Magellan wireless
expansion module
Paradox Wireless Products
• Transmitters– Motion Detectors
Wireless PIR Motion Detector with Built-in Pet Immunity (18kg/40lb Pet Immunity)
PMD2P
Digital Dual-Optic High Performance PIR
(40kg/90lbsTrue Pet Immunity)
MG-PMD75
Digital Dual-Optic High Performance Outdoor PIR (40kg/90lbs True Pet Immunity)
MG-PMD85
Paradox Wireless Products
– Door Contacts
Long-Range Door Contact
MG-DCT1
Ultra-Small Door Contact
MG-DCT2
Door Contact
MG-DCTXP
Paradox Wireless Products
– Remote Controls
Remote Control with Backlight Buttons
MG-REM1
2-Way Remote Control with Backlight Buttons
MG-REM2
Paradox Wireless Products
– Remote Controls
Magellan Remote Control with Magellan Remote Control with Integrated Access CardIntegrated Access Card
MG-RAC1MG-RAC1
Paradox Wireless Products
– Accessory
Smoke DetectorMade by EVERday (Taiwan)
SD738