HAM RADIO SCIENCE: IMPROVED FREED VHF DIGITAL AUDIO SOFTWARE NOW AVAILABLE A new upgrade to FreeDV has been released. Amateur Radio Newsline's Heather Embee, KB3TZD has the details: -- FreeDV is a part of a ham radio developed digital audio system that should eventually allow just about any SSB radio and any computer operating system to be teamed together. This to enable transmission and reception of what developers call high quality narrow-band digital audio for the High Frequency amateur radio bands. To make this happen speech is compressed and then modulated onto a 1100 Hz wide QPSK signal which is sent to the microphone input of a SSB radin receive, the signal is demodulated and decoded by the FreeDV software. The new upgrade called version dot 96 became available on March 23rd. It provides a 1600 bit-per-second mode that communicates at much lower signal levels than previously envisioned. As such, signals should be readable down to a 2 dB Signal to Noise Ratio, and long-distance contacts have already been reported using only 1 to 2 watts power. A compatibility mode for communication with the older dot 91 version is included. Developers say that an executable program for Windows is presently available. Also that Linux and other platforms will follow shortly. FreeDV was brought into being by an international team of radio amateurs working together on coding, design, user interface and testing. It 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.