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

Wireless Communication Basics

RF Basics Basic Communication System Transmitter and Receiver

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

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

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

RF Basics Maximizing Range Transmitter Receiver Antenna 1 Antenna 2

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

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

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

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

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

RF Basics Antenna Gain Government-imposed power restrictions Omnidirectional

RF Basics Antenna Gain Directional

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

RF Basics Fresnel Zone Football-shaped path Fresnel Zone

RF Basics Fresnel Zone Football-shaped path Acceptable = 60% of Zone 1 + 3 meters Raise antennas to help clear the zone

RF Basics Fresnel Zone Football-shaped path Acceptable = 60% of Zone 1 + 3 meters Raise antennas to help clear the zone Formula

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

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

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

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

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

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

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.

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.

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

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

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 bps Interface Packages Available

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.

Digi RF Products Modules (Embedded) Packaged (Boxed)

DigiRF Products XBee XStream XTend XPress XCite Digi Mesh

Product Brand Specs

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