AMRAD Meeting Reminder - Thursday August 8

[Karl W4KRL]

Thursday, August 8, 7:30 PM, Dolley Madison Library, McLean, VA.
<http://www.fairfaxcounty.gov/library/branches/dm/>  Maitland Bottoms,
AA4HS, will introduce us to digital voice communications on HF using FreeDV
software. FreeDV is an application for Windows, Linux and MacOS (BSD and
Android are in development) that allows any SSB radio to be used for low bit
rate digital voice. The software compresses speech to 1400 bit/s then
modulates a 1.1 kHz wide quadrature phase-shift keying (16-QPSK) signal
which is sent to the Mic input of a SSB radio. On receive, the signal is
received by the SSB radio, then demodulated and decoded by FreeDV.
Communications is readable down to 2 dB S/N, and long-distance contacts are
reported using 1-2 watts power. FreeDV is unique as it uses 100% Open Source
Software, including the audio codec. FreeDV represents a path for 21st
century Amateur Radio where Hams are free to experiment and innovate without
being locked into a single manufacturer's proprietary technology. The same
cables and hardware that you use for other digital modes that are based on
PC programs will work with FreeDV, but you will need a second sound
interface for the microphone and speaker connections to the FreeDV program.
A USB headset of the sort used by gamers is all you need for the second
sound interface.

freeDV.png

 

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