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Software Defined Radio (SDR) and its Implementation

Brandon Graham

W0GPR

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What is SDR

  • Instead of relying on RLC circuits, a raw, lightly filtered analog signal is converted to the digital domain to be further processed by digital systems
  • RF Front End ADC/DAC Computer

R.F.

Front End

High Quality

Sound Card

P.C., Laptop,

Netbook, or

Embedded

processor

Antenna

I,Q

I,Q

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Digital vs Analog

Digital

  • Discrete
  • Digital Signal Processing DSP
  • Filtering
  • Phase
  • Frequency
  • Time
  • Power

Analog

  • Continuous
  • Filtering
  • Power amplifier

​

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Flex Radio

  • Manufacturer of SDRs for Industry, Military and Amateur use starting in 2003
  • HF transceivers ranging from QRP to 100 watts
    • Flex 1500 – QRP/transverter IF
    • Signature series – Contest serious radio
    • *Flex 3000
    • *Flex 5000
    • *SDR 1000
      • *discontinued

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“The Feel of the Radio”

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“The Feel of the Radio”

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Power SDR

  • Graphical User Interface (GUI)
    • Radio’s buttons and knobs
  • Signal Processing
    • Filtering, DSP, Audio input and output shaping, etc
  • Rig control
    • Frequency, band, tuner
  • Program interface
    • VSPs, VACs, out to digital modes, logging, ext. aux

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“The Feel of the Radio”

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“The Feel of the Radio”

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Computer system/Software

  • VAC
    • Virtual Audio Cable
  • VSP Manager
    • Virtual Com/Serial Port
  • Com-0-Com
  • DDU Til
  • Logging
  • Digital Mode Program
  • Remote Operation
  • Processor
  • RAM
  • Screen usage
  • Quirks

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The system setup

Flex 3000

PowerSDR

VAC

DDU Til

VSP Manager

FL-DIGI

WSJT-X

N1MM+

Computer

Com Single

VAC Pair 1

VAC Pair 2

FireWire

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Pros / Cons of SDR over Analog

  • Pros
  • Filter visualization
  • Filter manipulation
  • Control of settings
  • Visually based displays
    • Panafall, etc.
  • DSP systems and control

​

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  • Cons
  • Quirky
  • Visually demanding
  • Computer intensive
  • Software setup
  • Need for multiple monitors and mouse
  • Not EmComm Ready

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“Let’s Play Radio”

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Remote Operation

  • Controlling computer, not radio
  • Everything must be powered up at radio and ready for control
  • Easier with digital over voice modes

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  • Lag
  • Control of accessory programs and screens

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WebSDR

  • University of Twente
    • Netherlands
  • Website designed for internet linked SDR receivers
  • Mostly centered on ham bands.

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Other SDR Systems

  • $20 Dongle
    • Nooelec.com
  • SDR SoftRock
  • HPSDR
  • ANAN
  • Genesis Radio
  • Rfspace

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  • Google is a friend!
  • Always New stuff added
  • Experimentation vs. “Solid Systems”
  • Many different programs
  • http://www.abrohamnealsoftware.com/products.php?cat=10