FDMDV Modem Page

I have added a FDMDV modem page to this web site, plus typed up a README_fdmdv.txt that explains all the files related to the modem and how to use them.

This modem was “lost” a few years ago as the initial implementation was closed source. So I felt compelled to put a fair bit of effort into documenting the open source implementation I have been working on. Building this modem was fun, just hard enough to be challenging but no real show stopper bugs and didn’t hurt my head like Codec 2 algorithm development.

Next step is to tweak Codec 2 to make it interface cleanly to the modem for some initial on-air tests.

IP0X Price Drop and Atcom IP Phones

Due to the consistently high Australian dollar we have lowered the prices of our IP0X range for Australian customers, for example the popular IP04 has been reduced from AUD$399 to AUD$349. We have also started distributing Atcom IP phones in Australia. These phones are very popular in other countries and we are looking for Australian resellers. Please Contact us for reseller pricing.

Codec 2 Over the Air

Some exciting developments this week with Codec 2 being used over the air for the first time!

Bruce, VE9QRP has written a script that allows Codec 2 calls over any IP network. He has tested it over the air using Laptop Wifi and is looking for people to contact him over the Internet.

Ben, VK6IC has tested Codec 2 on 145MHz using a home brew modem, all running on Windows (Ben’s work includes porting Codec 2 to Windows/MSVC). Ben had a contact with VK6UFO between Armadale and Ballajura (Western Australia), a distance of about 40 km. Ben has some off the air samples (including Speex at 8 kbit/s over the same channel) on his web site.

Sorin Cocorada has modified a Speex client to use Codec 2 and has been experimenting with simulated packet loss of up to 30%.

Fantastic work guys. It’s inspiring for me to see this level of interest in Codec 2. More discussion over on the Codec 2 Mailing list.

Codec2 V0.1 Alpha Released

I have just released V0.1 of the Codec2 low bit rate open source speech codec. Almost 1 year to the day since the project started with this post. Speech samples and lots of other new information on the Codec2 page.

I was convinced by many to release early with the current algorithm. After listening to some early MELP 2400 bit/s samples I realised we were already in the ball bark with speech quality. A V0.1 release gives people a chance to try out Codec2 while I work on the algorithm quality and bit rate in parallel.

Codec2 currently runs at 2550 bit/s and delivers fair speech quality. It runs 10 times faster than real time on a modest Linux laptop and is usable today for digital radio or VOIP experimentation.