RF Basics by Raoul van Bergen Field Application Engineer Embedded Digi International GmbH Dortmund...
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Transcript of RF Basics by Raoul van Bergen Field Application Engineer Embedded Digi International GmbH Dortmund...
![Page 1: RF Basics by Raoul van Bergen Field Application Engineer Embedded Digi International GmbH Dortmund raoul.van.bergen@digi.com.](https://reader035.fdocuments.in/reader035/viewer/2022062305/56649f4d5503460f94c6dc81/html5/thumbnails/1.jpg)
RF Basicsby
Raoul van BergenField Application Engineer EmbeddedDigi International GmbH Dortmund
![Page 2: RF Basics by Raoul van Bergen Field Application Engineer Embedded Digi International GmbH Dortmund raoul.van.bergen@digi.com.](https://reader035.fdocuments.in/reader035/viewer/2022062305/56649f4d5503460f94c6dc81/html5/thumbnails/2.jpg)
Wireless Communication Basics
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RF Basics• Basic Communication System
– Transmitter and Receiver
Transmitter Receiver
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RF BasicsBasic Communication System
– Transmitter and Receiver– Transmitting Antenna
Transmitter ReceiverAntenna 1
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RF BasicsBasic Communication System
– Transmitter and Receiver– Transmitting Antenna– Receiving Antenna
Transmitter ReceiverAntenna 1 Antenna 2
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RF BasicsBasic Communication System
– Transmitter and Receiver– Transmitting Antenna– Receiving Antenna– Environment
Transmitter ReceiverAntenna 1 Antenna 2
Environment
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RF BasicsMaximizing Range
Transmitter ReceiverAntenna 1 Antenna 2
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RF Essentials
Maximizing Range– Increase Transmitter (TX) Power
• Government Regulated• Low-powered Applications
Increase Power ReceiverAntenna 1 Antenna 2
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RF EssentialsMaximizing Range
– Increase Transmitter (TX) Power– Increase Receiver (RX) Sensitivity
• Specified in dBm• Every 6 dB doubles the range LOS• Every 12 dB doubles range indoors / urban
environments
IncreasePower
ImproveRX Sensitivity
IncreaseGain
IncreaseGain
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RF BasicsMaximizing Range
– Increase Transmitter (TX) Power– Increase Receiver (RX) Sensitivity– Increase Antenna Gain
• More gain equates with more focusing of energy• Antenna cables should be as short as possible
IncreasePower
ImproveRX Sensitivity
IncreaseGain
IncreaseGain
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RF Basics
Basic Communication System– Transmitter and Receiver– Transmitting Antenna
• Focused energy
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RF Basics
Basic Communication System– Transmitter and Receiver– Transmitting Antenna– Receiving Antenna
• Focused energy
![Page 13: RF Basics by Raoul van Bergen Field Application Engineer Embedded Digi International GmbH Dortmund raoul.van.bergen@digi.com.](https://reader035.fdocuments.in/reader035/viewer/2022062305/56649f4d5503460f94c6dc81/html5/thumbnails/13.jpg)
RF Basics
Antenna Gain– Government-imposed power
restrictions– Omnidirectional
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RF Basics
Antenna Gain– Directional
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RF BasicsMaximizing Range
– Increase Transmitter (TX) Power– Improve Receiver (RX) Sensitivity– Increase Antenna Gain– Clear the Environment of obstructions
• Visual (Linear) line-of-sight vs. RF (Radio) line-of-sight
IncreasePower
ImproveRX Sensitivity
IncreaseGain
IncreaseGain
Clear theEnvironment
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RF Basics
Fresnel Zone– Football-shaped path
FresnelZone
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RF BasicsFresnel Zone
– Football-shaped path– Acceptable = 60% of Zone 1 + 3 meters– Raise antennas to help clear the zone
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RF Basics
Fresnel Zone– Football-shaped path– Acceptable = 60% of Zone 1 + 3 meters– Raise antennas to help clear the zone– Formula
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RF BasicsFresnel Zone Diameters
RangeDistance
868 MHz ModemsRequired Fresnel
Zone Radius
2.4 GHz ModemsRequired Fresnel
Zone Radius
1 m 0,29 m 0,18 m
3 m 0,51 m 0,31 m
10 m 0,93 m 0,56 m
30 m 1,61 m 0,97 m
100 m 2,94 m 1,77 m
300 m 5,09 m 3,06 m
1600 m 11,76 m 7,07 m
8000 m 26,29 m 15,81 m
16000 m 37,18 m 22,36 m
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Importance of Frequency Selection
• Geographic Deployment– Worldwide versus Regional
• RF Performance– Range– RF Penetration– Antenna Considerations
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License-Free Bands
2.4 GHz
315 MHz420 MHz900 MHz5.7 GHz
900 MHz433 MHz
433 MHz868 MHz5.7 GHz
915 MHz
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Regulatory Bodies
• FCC (United States)• IC (Canada)• ETSI (Europe, some APAC)• C-Tick (Australia• Telec (Japan)• Anatel (Brazil)
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Rates and Ranges
Range
Pe
ak
Da
ta R
ate
Closer Farther
Slo
wer
Fas
ter
UWB Wireless Data Applications
Wireless Video Applications
IrDA
802.11g
802.11b
802.11a
2.5G/3G
Bluetooth™
ZigBee™Data
Transfer
Wireless Networking
Wi-Fi®
Cellular
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NodesNodes and Rates
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• Modem– Modulate / Demodulate
Radio Modem Operation
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Wireless Communication BasicsWhat is modulation?
– The process by which a parameter (amplitude, frequency or phase of a sinusoidal signal) of a higher frequency carrier wave is altered in accordance with the baseband message signal.
– Transforms the message signal into a form that is suitable for transmission over the channel.
– The transmitter uses the baseband message signal to modulate a carrier and transmit it over the channel.
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Radio Modem OperationTwo types of spread spectrum used in modern
Radios
1.FHSS- Frequency Hopping Spread Spectrum• Transmitter rapidly hops from one channel to the
next in a pseudo-random fashion, avoiding long-term interference.
• Receiver follows transmitter• Some Digi Products use FHSS
– 24XStream 2400 2480
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• Price-to-Performance Value
• High Receiver Sensitivity
• Low Power Consumption
• FCC (U.S.A.), IC (Canada), • ETSI (Europe) Approved
XStreamKey Features
Best Value OEM RF Modules 2.4GHz
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XStream (2.4 GHz)Best Value OEM RF Modules
Specifications
Indoor/urban Range up to 180 m
Outdoor line-of-sight Range up to 16 km
Transmit Power Output 50 mW (17 dBm)
Receiver Sensitivity -105 dBm @9600 bps
Operating Frequency 2.45-2.46 GHz
Operating Voltage 5V (OEM) 7-18 (Boxed)
RF Data Rate 9600 or 19200 bpsInterface Packages Available
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Radio Modem OperationTwo types of spread spectrum used in modern Radios
2. DSSS- Direct Sequence Spread Spectrum• Each bit is represented by N, shorter segments, called chips.• Increases over-the-air rate by a factor of N, widening the spectrum• Correlator in receiver examines the chips and maps chips back to bits,
while simultaneously spreading undesired signals• Processing gain, 10*log(chip_rate/bit_rate)• Some Digi products
use DSSS– XBee– XBee-Pro– All WiFi
enabledproducts
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Digi RF Products Packaged (Boxed)
Modules (Embedded)
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DigiRF Products
• XBee• XStream• XTend• XPress• XCite• Digi Mesh
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Product Brand Specs
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Product Name Frequency Power OutputIndoor RangeOutdoor Range
Data Rate
XBee 2.4 GHz 1 mW 30 meters100 meters
250 Kbps
XBee-PRO 2.4 GHz 50 mW100mW (EIRP)
100 meters1200 meters
250 Kbps
9XTend 900 MHz 1 Watt 900 meters64 kilometers
115 Kbps
9XStream 900 MHz 100 mW 450 meters32 kilometers
19.2 Kbps
24XStream 2.4 GHz 50 mW 180 meters16 kilometers
19.2 Kbps
9XCite 900 MHz 4 mW 90 meters300 meters
38.4 Kbps
Digi RF Modules
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