I have had a number of QSO's using FreeDV on a Flex6700 and I am very grateful to FlexRadio and the codec developers for the time and effort put into this project, it has a lot of interesting potential.
I would like to make the following comments:
If the aim on your radio is to make a readable transmission using the narrowest RF bandwidth over a wide range of signal strengths, then it currently does a good job and shows a massive advantage over SSB for audio signal to noise ratios on weak signals.
However, if you want to take advantage of the 6000 series ability to produce the finest transmit audio quality around, then it has a long way to go yet in terms of development.
Currently, using a full 3 kHz TX audio bandwidth, and high quality 5 channel digital audio processing, you can produce using SSB, an undistorted clarity and intelligability of audio rivalling AM and approaching that of FM.
Whilst an RF bandwidth of 1400Hz on DV is a great achievement, it would be nice to hope that as the mode develops we might be able to improve the resulting audio bandwidth to around 4.5 kHz, whilst still maintaining an RF envelope somewhat less than the normally accepted 3.0 kHz.
G4BIM Isle of Wight U.K.
This page http://www.rowetel.com/blog/?page_id=452 is worth reading and note that the main objective is "to make FreeDV better than SSB"
I think that's achievable -- given that even in the early days of dial-up Internet, we were squeezing 48 kbps out of a copper landline.
All the best,
I have now tested this mode to death over the last week or so.
Yes it works....just.
If they concentrated only making use of the brilliant Flex technology to produce wonderful digital audio and didn't try to cram too much into the tiniest RF bandwidth, then we would have on HF, a great new product/mode.
I sent the following E-Mail to the digitalvoice google group last week, so far no acknowledgement or comment.Thank you for the work you have done on the mode so far, I am using a FlexRadio 6700.
I am very happy to
make a donation.
Could you please
indicate if we might look forward in the near future to a second release which
would allow a wider transmit audio bandwidth.
I would imagine we could achieve transmitted audio of up to 4.5 kHz with a codec producing an RF transmit bandwidth stiil well below 3 kHz
For me the mode is 'Parked'. I live in hope.