1. RF Basics Raoul van Bergen raoul.van.bergen@digi.com by
Field Application Engineer Embedded
Digi International GmbH Dortmund

2. Wireless Communication Basics

3. RF Basics Basic Communication System Transmitter and Receiver

4. RF Basics Basic Communication System Transmitter and Receiver
Transmitting Antenna
Transmitter
Receiver
Antenna 1

5. RF Basics Basic Communication System Transmitter and Receiver
Transmitting Antenna
Receiving Antenna
Transmitter
Receiver
Antenna 1
Antenna 2

6. RF Basics Basic Communication System Environment
Transmitter and Receiver
Transmitting Antenna
Receiving Antenna
Environment
Environment
Transmitter
Receiver
Antenna 1
Antenna 2

7. RF Basics
Maximizing Range
Transmitter
Receiver
Antenna 1
Antenna 2

8. RF Essentials Maximizing Range Increase Transmitter (TX) Power
Government Regulated
Low-powered Applications
Increase Power
Receiver
Antenna 1
Antenna 2

9. RF Essentials Maximizing 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
Increase
Power
Improve
RX Sensitivity
Gain

10. RF Basics Maximizing 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
Increase
Power
Improve
RX Sensitivity
Gain

11. RF Basics Basic Communication System Transmitter and Receiver
Transmitting Antenna
Focused energy

12. RF Basics Basic Communication System Transmitter and Receiver
Transmitting Antenna
Receiving Antenna
Focused energy

13. RF Basics Antenna Gain Government-imposed power restrictions
Omnidirectional

14. RF Basics
Antenna Gain
Directional

15. RF Basics Clear the Environment Maximizing 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
Clear the
Environment
Increase
Power
Improve
RX Sensitivity
Gain

16. RF Basics
Fresnel Zone
Football-shaped path
Fresnel
Zone

17. RF Basics Fresnel Zone Football-shaped path
Acceptable = 60% of Zone meters
Raise antennas to help clear the zone

18. RF Basics Fresnel Zone Football-shaped path
Acceptable = 60% of Zone meters
Raise antennas to help clear the zone
Formula

19. Required Fresnel Zone Radius
RF Basics
Fresnel Zone Diameters
Range
Distance
868 MHz Modems
Required Fresnel Zone Radius
2.4 GHz Modems
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

20. Importance of Frequency Selection
Geographic Deployment
Worldwide versus Regional
RF Performance
Range
RF Penetration
Antenna Considerations

21. License-Free Bands 2.4 GHz 315 MHz 433 MHz 420 MHz 868 MHz 900 MHz

22. Regulatory Bodies FCC (United States) IC (Canada)
ETSI (Europe, some APAC)
C-Tick (Australia
Telec (Japan)
Anatel (Brazil)

23. Wireless Data Applications Wireless Video Applications
Rates and Ranges
Range
Voice
Video
Peak Data Rate
Closer
Farther
Slower
Faster
UWB
Wireless Data Applications
Wireless Video Applications
IrDA
802.11g
802.11b
802.11a
2.5G/3G
Monitoring
& Control
Bluetooth™
ZigBee™
Data
Transfer
Wireless Networking
Wi-Fi®
Cellular

24. Nodes Nodes and Rates Nodes vs. Data rate
This slide discusses the number of nodes possible in the different technologies. 24

25. Radio Modem Operation Modem Modulate / Demodulate
Modulate & Demodulate. Discuss meaning of Modulate – To adjust or regulate. With you car radio you can pick up two different types of signals  AM & FM.

26. Wireless Communication Basics
What 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.

27. Two types of spread spectrum used in modern Radios
Radio Modem Operation
Two types of spread spectrum used in modern Radios
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
Talking Point: Advantages of FM over AM. Discuss Noise improvement and FM “Capture Effect”. Our Radio Modems modulate serial data.
2400
2480

28. Best Value OEM RF Modules 2.4GHz
XStream Key Features
Price-to-Performance Value
High Receiver Sensitivity
Low Power Consumption
FCC (U.S.A.), IC (Canada),
ETSI (Europe) Approved
Best Value OEM RF Modules 2.4GHz

29. 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 bps
Operating Frequency
GHz
Operating Voltage
5V (OEM) 7-18 (Boxed)
RF Data Rate
9600 or bps
Interface Packages Available

30. Two types of spread spectrum used in modern Radios
Radio Modem Operation
Two types of spread spectrum used in modern Radios
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 enabled products
Talking Point: Advantages of FM over AM. Discuss Noise improvement and FM “Capture Effect”. Our Radio Modems modulate serial data.

31. Digi RF Products
Modules (Embedded)
Packaged (Boxed)

32. DigiRF Products
XBee
XStream
XTend
XPress
XCite
Digi Mesh

33. Product Brand Specs

34. Digi RF Modules XBee 2.4 GHz 1 mW 30 meters 100 meters 250 Kbps
Product Name
Frequency
Power Output
Indoor Range Outdoor Range
Data Rate
XBee
2.4 GHz
1 mW
30 meters 100 meters
250 Kbps
XBee-PRO
50 mW
100mW (EIRP)
100 meters 1200 meters
9XTend
900 MHz
1 Watt
900 meters 64 kilometers
115 Kbps
9XStream
100 mW
450 meters 32 kilometers
19.2 Kbps
24XStream
180 meters 16 kilometers
9XCite
4 mW
90 meters 300 meters
38.4 Kbps