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Surfin’: iPhone Gets Software Defined Radio


By Stan Horzepa, WA1LOU
Contributing Editor

This week, Surfin’ discovers a software defined radio (SDR) in an iPhone.

This is so cool, my typing fingers are numb from the cold: a software defined radio (SDR) application for the Apple iPhone, iPod touch and iPad called iSDR. It is a portable software-defined radio receiver designed for experimenters, shortwave listeners and Amateur Radio operators -- and it is free! 

A caveat: receiving live on-the-air signals with iSDR requires purchasing or constructing a quadrature sampling detector (QSD) RF front-end device that connects between an antenna and the microphone input jack of the iPhone, iPod or iPad. Without the front-end, iSDR will play an internal audio file recording of actual radio signals recorded off the air during the 2008 CQ World Wide WPX contest.

The iSDR developers list the following features of the app:

  • Three display modes: Spectrum, Waterfall and Oscilloscope
  • Frequency display with 100 Hz resolution with a touch to the display screen
  • Up to 44.1 kHz of available spectrum bandwidth
  • Monaural microphone input automatically adjusts display to 22 kHz bandwidth
  • Automatic display rotation
  • Recorded audio file built in for off-line use without external audio
  • Automatically detects if external audio is available
  • Five receive modes: USB, LSB, CW, DSB and Binaural
  • Reverse I/Q microphone input logic
  • User-adjustable center frequency setting

Visit the iSDR developer’s Web site for more information.

Still Got Batteries 

Last week’s Surfin’ -- Got Batteries -- moved Phil Minch, K6MUG, to write: “I would like to mention a book I just happened across. I haven’t got into it yet so I can't critique it, but the subject matter was irresistible. It’s titled The Battery, How Portable Power Sparked a Technological Revolution by Henry Schlesinger. It has a wonderful retro design cover styled after an Eveready battery which made me grab it off the shelf at the book store.”

Phil’s missive moved me to check out the book on Amazon. The book does look interesting and I found “ham radio” listed twice in the book’s index, so I must peruse the book next time I visit a brick-and mortar-book emporium.

Until next time, keep on surfin’.

Editor note: Stan Horzepa, WA1LOU, wonders who stole the kishka; someone call a cop. To contact Stan, send him e-mail or add comments to his blog.



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