FREE DV IS A GREAT MODE

Tim KE4UK

HAD MY FIRST QSO ON FREEDV THIS EVENING ON 14.236 WITH WB9TLH WAS A REALLY ENJOYABLE EXPERIENCE, TNX FLEX RADIO

k3Tim

Congrats and well done....

I have heard many a QSO but haven't been heard yet.  :-)

k3Tim

Tim KE4UK

I was fortunate, on my first try I connected but his signal was 10 over s9

k3Tim

Wow! That's fortunate.  

I have an inefficient end fed antenna and the FDV signals were rather low.  This mode, I thought, was good for low power but seems it's more a high power mode or gain antennas.

Best,
k3Tim

Tim KE4UK

I was transmitting 40 watts on an inverted vee cut for 3.965 mhz running through the ATU.

Peter Bentley

Interesting mode, but needs a lot more development.

Tim KE4UK

Think that may be the idea.

Joe, KQ1Q

FreeDV is interesting and quite an achievement to cram an understandable phone signal into 1.4Khz. It is nice that FRS added it to SSDR, and it's easy to use vs other implementations that require two sound cards.

OTOH the current codec implementation is susceptible to fading, esp. frequency-selective fading which is common on HF. This can be recognized by the diagonal stripes in the waterfall display. This somewhat nullifies the weak signal potential of digital voice. 

There's no way to adjust EQ in the current SSDR version, so the codec does whatever it decides with the AF curve. In general the speech quality is significantly artifacted, but understandable. Ideally Proc and EQ should be disabled in the current version.

It is interesting that the gigantic advantage digital modes have for text (PSK31, etc) are harder to realize for voice. 

A lot of work is being done on the codec and hopefully future versions will be significantly improved. If widely adopted FreeDV could provide a common digital voice mode (IOW the new SSB), vs a proliferation of incompatible digital modes.

Ken - NM9P

I agree that PROC should be turned odd. But I have found that I get a better TX if I roll off lows and boost a few of the highs. Apparently too many low frequencies contribute to artifacts that give it a more robotic sound. It would be nice if they retuned the codec for a channel or two more bits and added some FEC, etc.