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

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Wireless Communication Basics

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Wireless Communication Basics


Transmitter

Receiver

RF Basics

  • Basic Communication System

    • Transmitter and Receiver


Transmitter

Antenna 1

Receiver

RF Basics

Basic Communication System

  • Transmitter and Receiver

  • Transmitting Antenna


Transmitter

Antenna 1

Antenna 2

Receiver

RF Basics

Basic Communication System

  • Transmitter and Receiver

  • Transmitting Antenna

  • Receiving Antenna


Transmitter

Antenna 1

Antenna 2

Receiver

RF Basics

Basic Communication System

  • Transmitter and Receiver

  • Transmitting Antenna

  • Receiving Antenna

  • Environment

Environment


Transmitter

Antenna 1

Antenna 2

Receiver

RF Basics

Maximizing Range


Increase Power

Antenna 1

Antenna 2

Receiver

RF Essentials

Maximizing Range

  • Increase Transmitter (TX) Power

    • Government Regulated

    • Low-powered Applications


Increase

Power

Increase

Gain

Increase

Gain

Improve

RX Sensitivity

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

Increase

Gain

Increase

Gain

Improve

RX Sensitivity

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


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


Increase

Power

Increase

Gain

Increase

Gain

Improve

RX Sensitivity

RF Basics

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


Fresnel

Zone

RF Basics

Fresnel Zone

  • Football-shaped path


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


RF Basics

Fresnel Zone Diameters


Importance of Frequency Selection

Geographic Deployment

Worldwide versus Regional

RF Performance

Range

RF Penetration

Antenna Considerations


License-Free Bands

2.4 GHz

315 MHz

420 MHz

900 MHz

5.7 GHz

433 MHz

868 MHz

5.7 GHz

900 MHz

433 MHz

915 MHz


Regulatory Bodies

FCC (United States)

IC (Canada)

ETSI (Europe, some APAC)

C-Tick (Australia

Telec (Japan)

Anatel (Brazil)


Rates and Ranges

Wireless Video Applications

Faster

Video

UWB

Data

Wireless Data Applications

802.11g

802.11a

IrDA

Wi-Fi®

Voice

Peak Data Rate

802.11b

Cellular

2.5G/3G

Bluetooth™

Monitoring

& Control

Data

Transfer

ZigBee™

Slower

Wireless Networking

Closer

Farther

Range


Nodes

Nodes and Rates


Radio Modem Operation

  • Modem

    • Modulate / Demodulate


Modulation

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.


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

2400

2480


XStreamKey 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

Interface Packages Available


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 productsuse DSSS

      • XBee

      • XBee-Pro

      • All WiFi enabledproducts


Digi RF Products

Modules (Embedded)

Packaged (Boxed)


DigiRF Products

  • XBee

  • XStream

  • XTend

  • XPress

  • XCite

  • Digi Mesh


Digi RF Modules


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