<h1 id="Introduction" class="showhide_heading">Introduction</h1>
<div>FreeDV is a GUI application for Windows, Linux and MacOS (BSD and Android in development) that allows any SSB radio to be used for low bit rate digital voice.<br><br>Speech is compressed down to 1600 bit/s then modulated onto a 1.25 kHz wide 16QPSK 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 should be readable down to 2 dB S/N, and long-distance contacts are reported using 1-2 watts power.<br>
<br>FreeDV was built by an international team of Radio Amateurs working together on coding, design, user interface and testing. FreeDV is open source software, released under the GNU Public License version 2.1. The FDMDV modem and Codec 2 Speech codec used in FreeDV are also open source.<br>
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<h2 id="New_Upgrade_as_of_version_0.96.5" class="showhide_heading">New Upgrade as of version 0.96.5</h2>August 15, 2013: Repairs T/R switching (including both serial control line switching and hamlib serial commands) and a conflict in the use of the space bar between the options panel and T/R switching.<br>
<h2 id="Why_FreeDV_" class="showhide_heading">Why FreeDV?</h2>Amateur Radio is transitioning from analog to digital, much as it transitioned from AM to SSB in the 1950's and 1960's. How would you feel if one or two companies owned the patents for SSB, then forced you to use their technology, made it illegal to experiment with or even understand the technology, and insisted you stay locked to it for the next 100 years? That's exactly what <em>was</em> happening with digital voice. But now, hams are in control of their technology again!<br>
<br>FreeDV is unique as it uses 100% Open Source Software, <em>including</em> the audio codec. No secrets, nothing proprietary! FreeDV represents a path for 21st century Amateur Radio where Hams are free to experiment and innovate, rather than a future locked into a single manufacturers closed technology.<br>
<h2 id="Demo_Video" class="showhide_heading">Demo Video</h2><a class="wiki wiki_page" title="video" href="http://freedv.org/tiki-index.php?page=video">Watch this video</a> of a FreeDV QSO.<br>
<h2 id="Here_is_what_you_need:" class="showhide_heading">Here is what you need:</h2>
<ul>
<li>A SSB receiver or transceiver </li>
<li>FreeDV software, download links are below. </li>
<li>A Windows or Linux PC with one (receive only) or two sound cards. </li>
<li>Cables to connect your PC to your SSB radio. </li></ul>
<h3 id="Test_your_Transmitter_Frequency_Response" class="showhide_heading">Test your Transmitter Frequency Response</h3>When you play <a class="wiki external" href="http://rowetel.com/downloads/codec2/1k_2k_sweep.wav" rel="external nofollow" target="_blank">this 10 second 1 kHz to 2 kHz sweep .wav file</a><img class="icon" title="(external link)" alt="(external link)" src="http://freedv.org/img/icons/external_link.gif" width="15" height="14"> through your transmitter, the power level should remain constant. If not, look for filtering and processing to turn off.<br>
<h3 id="Connecting_Your_Radio" class="showhide_heading">Connecting Your Radio</h3>If you are lucky enough to have a "9600" input and output on your radio, this is the best connection for every digital mode, even 1200 packet, and your audio box should be configured for 9600 or "no pre-emphasis/de-emphasis" if it has that setting. If the radio's configuration menu has a 1200/9600 setting, leave it permanently on 9600.<br>
<br>The "9600" and "1200" settings are misnamed. "9600" should really be called "direct connection", and "1200" should be called "pre-emphasis". The pre-emphasis that comes with the 1200 setting doesn't help any digital mode. The 9600 connection is the most direct and unprocessed path to the modulator and demodulator of your radio.<br>
<br>Those who don't have a special connection for digital modes can use the normal audio inputs and outputs of your radio. 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.<br>
<h3 id="Configuring_Your_Radio" class="showhide_heading">Configuring Your Radio</h3>Turn off as much processing as possible. In general noise blankers, DSP band limit filtering and narrow bandpass filters are more likely to hurt than help, while compression, DSP noise or carrier elimination, and voice processing are <em>definitely</em> wrong for Digital modes. FreeDV's HF modem does its own DSP, and in general this is true for other digital programs as well.<br>
<br>You can see the received effect of different settings in the S/N (signal to noise ratio) display of FreeDV. A higher S/N is better.<br><br>Drive your transmitter and amplifier so that it emits 10% to 20% of its rated power continuously. There is a 12 dB peak-to-average power ratio in our HF modem, and peak clipping in your amplifier will reduce the received S/N. Modern transmitters and amplifiers are only as linear, and only have as much headroom, as is necessary for voice SSB, thus we suggest you maintain amplifier headroom by operating well below your full power output. FreeDV is more efficient than SSB voice, and will achieve similar range to an SSB signal driven at higher levels, and better audio quality. We encourage you to ask manufacturers and reviewers to start rating transmitter and amplifier linearity and headroom for <em>digital</em> modes, not just SSB voice.<br>
<h2 id="Download" class="showhide_heading">Download</h2>
<ul>
<li><a class="wiki external" href="http://files.freedv.org/FreeDV-0.96.5-win32.exe" rel="external nofollow" target="_blank">Windows Installer (NEW!)</a><img class="icon" title="(external link)" alt="(external link)" src="http://freedv.org/img/icons/external_link.gif" width="15" height="14">. </li>
<li><a class="wiki external" href="http://files.freedv.org/freedv-windows.zip" rel="external nofollow" target="_blank">Windows binary files</a><img class="icon" title="(external link)" alt="(external link)" src="http://freedv.org/img/icons/external_link.gif" width="15" height="14">. </li>
<li><a class="wiki external" href="http://files.freedv.org/OSX" rel="external nofollow" target="_blank">Macintosh OSX</a><img class="icon" title="(external link)" alt="(external link)" src="http://freedv.org/img/icons/external_link.gif" width="15" height="14">. </li>
<li><a class="wiki external" href="http://files.freedv.org/debian" rel="external nofollow" target="_blank">Debian package repository, Wheezy x86 and amd64</a><img class="icon" title="(external link)" alt="(external link)" src="http://freedv.org/img/icons/external_link.gif" width="15" height="14">. </li>
<li><a class="wiki external" href="http://files.freedv.org/freedv-repo-1.0-1.el.noarch.rpm" rel="external nofollow" target="_blank">Red Hat Enterprise Linux repository set-up RPM</a><img class="icon" title="(external link)" alt="(external link)" src="http://freedv.org/img/icons/external_link.gif" width="15" height="14">. </li>
<li><a class="wiki external" href="http://files.freedv.org/el" rel="external nofollow" target="_blank">Red Hat Enterprise Linux 6 repositories, i686 and x86_64</a><img class="icon" title="(external link)" alt="(external link)" src="http://freedv.org/img/icons/external_link.gif" width="15" height="14">. </li>
<li><a class="wiki external" href="http://files.freedv.org/freedv-repo-1.0-1.fedora.noarch.rpm" rel="external nofollow" target="_blank">Fedora repository set-up RPM</a><img class="icon" title="(external link)" alt="(external link)" src="http://freedv.org/img/icons/external_link.gif" width="15" height="14">. </li>
<li><a class="wiki external" href="http://files.freedv.org/fedora" rel="external nofollow" target="_blank">Fedora repositories, Fedora 17, 18, 19, i686 and x86_64</a><img class="icon" title="(external link)" alt="(external link)" src="http://freedv.org/img/icons/external_link.gif" width="15" height="14">. </li>
<li><a class="wiki external" href="http://blog.jms.id.au/2013/02/freedv-on-android" rel="external nofollow" target="_blank">Android</a><img class="icon" title="(external link)" alt="(external link)" src="http://freedv.org/img/icons/external_link.gif" width="15" height="14"> under development. </li>
</ul>You can also build from <a class="wiki external" href="http://freetel.svn.sourceforge.net/svnroot/freetel" rel="external nofollow" target="_blank">source code</a><img class="icon" title="(external link)" alt="(external link)" src="http://freedv.org/img/icons/external_link.gif" width="15" height="14">, project files are in the fdmdv2 and codec2-dev folders. Information on how to set up read-only access to Subversion is <a class="wiki external" href="http://sourceforge.net/scm/?type=svn&group_id=217466" rel="external nofollow" target="_blank">here</a><img class="icon" title="(external link)" alt="(external link)" src="http://freedv.org/img/icons/external_link.gif" width="15" height="14">.<br>
<h2 id="Quick_Start_Guide" class="showhide_heading">Quick Start Guide</h2>Several start-up guides are available<br>
<ul>
<li><a class="wiki wiki_page" title="Microsoft Windows Quick Start Guide" href="http://freedv.org/tiki-index.php?page=Microsoft+Windows+Quick+Start+Guide">Microsoft Windows Users Quick Start</a> </li>
<li><a class="wiki wiki_page" title="Video Microsoft Windows Quick Start Guide" href="http://freedv.org/tiki-index.php?page=Video+Microsoft+Windows+Quick+Start+Guide">Video Guide for Microsoft Windows Users</a> </li>
<li><a class="wiki external" href="http://www.youtube.com/watch?v=7pSj7IZfGKI" rel="external nofollow" target="_blank">Video Quick Guide to Microphones</a><img class="icon" title="(external link)" alt="(external link)" src="http://freedv.org/img/icons/external_link.gif" width="15" height="14"> </li>
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<h2 id="Useful_Frequencies" class="showhide_heading">Useful Frequencies</h2>USA, 14.236 MHz<br>Login to FreeDV QSO Finder for list of frequencies </div>
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<h2 id="Support" class="showhide_heading">Support</h2>
<div>Please post your questions to the "Digital Voice" Google group: <a href="mailto:digitalvoice@googlegroups.com">digitalvoice@googlegroups.com</a><br><br></div>
<h2 id="Design_REAL_AMP_Key_Features" class="showhide_heading">Design & Key Features</h2>
<div>Design:<br></div>
<ul>
<li>Codec 2 voice codec and FDMDV modem </li>
<li>50 baud 16 QPSK voice data </li>
<li>1 Center BPSK carrier with 2x power for fast and robust synchronisation. </li>
<li>1.25 kHz spectrum bandwidth (half SSB) with 75 Hz carrier spacing </li>
<li>1400 bit/s data rate with 1375 bit/s voice coding, 25 bit/s text for call sign ID, 200 bit/s FEC. </li>
<li>No interleaving in time, resulting in low latency, fast synchronization and quick recovery from fades. </li>
<li>44.1 or 48kHz sample rate sound card compatible </li></ul>
<div>Key Features:<br></div>
<ul>
<li>Cross platform, runs on Linux, Windows, MacOS, BSD, and a Java version runs on Android. </li>
<li>Open source, patent free Codec and Modem that anyone can experiment with and modify </li>
<li>Waterfall, spectrum, scatter and audio oscilliscope displays. </li>
<li>Adjustable squelch </li>
<li>Fast/slow SNR estimation </li>
<li>Microphone and Speaker signal audio Equaliser </li>
<li>Control of Transmitter PTT via RS232 levels </li>
<li>Works with one (receive only) or two (transmit and receive) sound cards, for example a built in sound card and USB headphones. </li></ul>
<h2 id="Credits" class="showhide_heading">Credits</h2>
<div>FreeDV was coded from scratch by David Witten (GUI, architecture) and David Rowe (Codec 2, modem implementation, integration).<br><br>The FreeDV design and user interface is based on FDMDV, which was developed by Francesco Lanza, HB9TLK. Francesco received advice on modem design from Peter Martinez G3PLX, who has also advised David on the FDMDV modem used in FreeDV.<br>
<br>Mel Whitten, K0PFX has contibuted greatly to the design, testing and promotion of several Digital Voice systems, including FDMDV. This practical experience has led to the current design – a fast sync, no FEC, low latency system that gives a “SSB” type feel for operators. Mel and a team of alpha testers (Gerry, N4DVR; Jim, K3DCC; Rick, WA6NUT; Tony, K2MO) provided feedback on usability and design of FreeDV.<br>
<br>Bruce Perens has been a thought leader on open source, patent free voice codecs for Amateur Radio. He has inspired, promoted and encouraged the development of Codec 2 and FreeDV.<br><br>As development continues, a great many people are pitching in whom we have not credited on this web site, but we appreciate all of their work.<br>
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<h1 id="Developer_Resources" class="showhide_heading">Developer Resources</h1>
<div>There is a free, if somewhat old, wxWidgets book that you can download <a class="wiki external" href="http://www.phptr.com/content/images/0131473816/downloads/0131473816_book.pdf" rel="external nofollow" target="_blank">here</a><img class="icon" title="(external link)" alt="(external link)" src="http://freedv.org/img/icons/external_link.gif" width="15" height="14">.<br>
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<h1 id="Links" class="showhide_heading">Links</h1>
<div><a class="wiki external" href="http://groups.google.com/group/digitalvoice" rel="external nofollow" target="_blank">Google DigitalVoice group</a><img class="icon" title="(external link)" alt="(external link)" src="http://freedv.org/img/icons/external_link.gif" width="15" height="14"><br>
<a class="wiki external" href="http://n1su.com/fdmdv/" rel="external nofollow" target="_blank">FDMDV Digital Voice Resource Page</a><img class="icon" title="(external link)" alt="(external link)" src="http://freedv.org/img/icons/external_link.gif" width="15" height="14"><br>
<a class="wiki external" href="http://rowetel.com/codec2.html" rel="external nofollow" target="_blank">Codec 2 Voice Codec</a><img class="icon" title="(external link)" alt="(external link)" src="http://freedv.org/img/icons/external_link.gif" width="15" height="14"><br>
<a class="wiki external" href="http://rowetel.com/blog/?page_id=2458" rel="external nofollow" target="_blank">FDMDV Modem</a><img class="icon" title="(external link)" alt="(external link)" src="http://freedv.org/img/icons/external_link.gif" width="15" height="14"><br>
<a class="wiki external" href="http://codec2.org/" rel="external nofollow" target="_blank">Why Open Source Digital Voice Is Important</a><img class="icon" title="(external link)" alt="(external link)" src="http://freedv.org/img/icons/external_link.gif" width="15" height="14"><br>
<a class="wiki wiki_page" title="FreeDV Specification" href="http://freedv.org/tiki-index.php?page=FreeDV+Specification">FreeDV Specification</a><br><a class="wiki wiki_page" title="Tigertronics" href="http://freedv.org/tiki-index.php?page=Tigertronics">Notes for users of Tigertronics rig interfaces</a><br>
<a class="wiki external" href="http://qso.k7ve.org/" rel="external nofollow" target="_blank">K7VE's FreeDV QSO Finder</a><img class="icon" title="(external link)" alt="(external link)" src="http://freedv.org/img/icons/external_link.gif" width="15" height="14"><br>
<a class="wiki external" href="http://www.youtube.com/watch?v=Nzf4XCCwHoI" rel="external nofollow" target="_blank">David Rowe interviewed about CODEC2</a><img class="icon" title="(external link)" alt="(external link)" src="http://freedv.org/img/icons/external_link.gif" width="15" height="14"><br>
<a class="wiki external" href="http://arvideonews.com/hrn/" rel="external nofollow" target="_blank">HamRadioNow.tv Episode 81 Bruce Parens and Mel Whitten interview at Dayton Hamvention 2013</a><img class="icon" title="(external link)" alt="(external link)" src="http://freedv.org/img/icons/external_link.gif" width="15" height="14"><br>
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<h1 id="FAQ" class="showhide_heading">FAQ</h1>
<div>Q1: Is there any way to save the screen settings when you drag the tabs to multiple windows on the main screen?<br>A1: No, as we can't work out how to support saving and restoring this information with wxWidgets.</div>
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<div>More Info: <a href="http://freedv.org/tiki-index.php">http://freedv.org/tiki-index.php</a><br><br></div>