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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 l.jpg

Wireless Communication Basics


Rf basics l.jpg

Transmitter

Receiver

RF Basics

  • Basic Communication System

    • Transmitter and Receiver


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Transmitter

Antenna 1

Receiver

RF Basics

Basic Communication System

  • Transmitter and Receiver

  • Transmitting Antenna


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Transmitter

Antenna 1

Antenna 2

Receiver

RF Basics

Basic Communication System

  • Transmitter and Receiver

  • Transmitting Antenna

  • Receiving Antenna


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Transmitter

Antenna 1

Antenna 2

Receiver

RF Basics

Basic Communication System

  • Transmitter and Receiver

  • Transmitting Antenna

  • Receiving Antenna

  • Environment

Environment


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Transmitter

Antenna 1

Antenna 2

Receiver

RF Basics

Maximizing Range


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Increase Power

Antenna 1

Antenna 2

Receiver

RF Essentials

Maximizing Range

  • Increase Transmitter (TX) Power

    • Government Regulated

    • Low-powered Applications


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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


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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


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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


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RF Basics

Antenna Gain

  • Government-imposed power restrictions

  • Omnidirectional


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RF Basics

Antenna Gain

  • Directional


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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


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Fresnel

Zone

RF Basics

Fresnel Zone

  • Football-shaped path


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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


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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 Basics

Fresnel Zone Diameters


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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 MHz

420 MHz

900 MHz

5.7 GHz

433 MHz

868 MHz

5.7 GHz

900 MHz

433 MHz

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

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


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Nodes

Nodes and Rates


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Radio Modem Operation

  • Modem

    • Modulate / Demodulate


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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.


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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


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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


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XStream (2.4 GHz)Best Value OEM RF Modules

Interface Packages Available


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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


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Digi RF Products

Modules (Embedded)

Packaged (Boxed)


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DigiRF Products

  • XBee

  • XStream

  • XTend

  • XPress

  • XCite

  • Digi Mesh


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Digi RF Modules


  • Login