AMRAD Meeting Tonight 7:30 Dolley Madison Library

[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.

 

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