Digital Voice - FreeDV

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  • Updated 5 years ago
OK, I thought I read where FreeDV (Digital Voice) might be included in release 1.4

So, those of you not familiar with Digital Voice, here is a link (a little long) explaining it:

Interesting that this 'mode' takes about 1200 Hz bandwidth (among other advantages)

It is my opinion that the hobby will 'eventually' migrate this route. Sort of like AM in the 1950's, then converting to SSB. There will probably always be AM folks, and also SSB folks, no problem. We all enjoy the hobby in different ways.

This reminds me of a company I used to work for - Motorola. In the early nineties, a senior VP at Corporate decided that analog was the only way to go with cell phones. After all, Motorola owned the cell phone market then. Oops! Everyone went digital and Moto took many years to catch up. Lost market share, etc...

Enough ranting - if not in 1.4 maybe in the next one. Looking forward to digital, here...

My .02

Alan, W4FBI
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Alan W4FBI

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Posted 5 years ago

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Mike W9OJ

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One possible downside is 100% duty cycle. Just like AM.

73 de Mike W9OJ
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Lee, Elmer

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But then you can run class C and you don't need a high level modulator 
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The Flex 6xxx series can do 100% duty cycle modes at full power. Had it officially confirmed.

Regarding v1.4; FreeDV/Waveform API was in, then removed and I have only heard rumours (it's nothing to do with release dates FRS - pls keep us informed) that it could be in again.
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FreeDV is expected in 1.4:

I see the FreeDV folks congregate in the phone segment, but can this be used in the digital section?  If FCC grants digital modes to USA-Technician then this would open up voice mode on lower HF bands to same.

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Alex - DH2ID, Elmer

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I have tried DV on HF and we also put up a D-Star repeater last year.
What is common to all digital voice modes is that you need quite a bit
more power to get an uninterrupted voice data stream.
Whereas analog modes just vanish into the noise level during a
fading on the band and crop up again, digital voice data streams
either are decoded fully or not at all.
We call these data stream interruptions R2D2, after the star wars
character with it's funny voice.
IMHO DV will have it's niche as it sounds quite good, but I doubt whether
it will have it's uses for DXing or contesting.
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Norm - W7CK

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I'm looking forward to playing with Digital Voice.  Will it be the next big thing in radio - who knows.

Last night I was down on 80m for a change.  I noticed a large number of stations were running at least 3500 - 4500 Hz wide.  There were 2 stations that must have been around 5,000 Hz or more.  It seems to be a growing trend to run SSB about as wide as one can in an effort to have "broadcast quality audio".  2 guys were actually discussing how wide there signals were with pride.  They were pretty arrogant about it saying how they don't even care if they in interfere with other stations or not.  "The wider the better" was one comment.  One person said it even helps keep other operators farther away from HIS frequency and reduces his QRM.  Anyone else noticing this trend?
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Ken - NM9P

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There are a few guys operating ESSB on the low end of 80 where there is usually plenty of room, especially late at night unless some self-appointed RF cops intentionally try to push it and move in really close just to prove a point.  They usually hang out on 3630 and 3636.  a width of 6 KHz is about the standard, which is more narrow than a standard full AM signal, and no carrier.    My philosophy is there should be room for a couple of channels of this, just like there is room for a few AM'ers, or FM ops on 10 Meters.  

Outside of the usual ESSB frequencies, I think that hams should keep within the standard 3 Khz bandwidth, especially when the band is crowded.  I don't really see the point, for example, of operating at 4.5 Wide on 17 meters where the band is already pretty narrow.

Yes, there are a  few arrogant folks in the ESSB crowd, but I have actually found more intolerance among those who hate it and intentionally interfere, gripe and moan, and push the issue.  I have seen guys move right in on them and interfere when there was 100 KHz completely open right next door, but these "principled" operators created a fight just for the "principle" of the thing. 

I have also seen Narrow USB guys move right on on an AM station so that their LSB signal was messing up an AM'er's upper sideband and caused great interference.  

On the other hand, I have seen a couple of ESSB'ers move in when someone was 4 Khz below them and open up to 6.5 Khz wide and smash them.  But I haven't seen that as often as I have seen the other.  

This hobby is wonderful garden of varied interests.  We should all be tolerant of varying interests and operating preferences.  Rudeness of any sort is not called for.

Full Disclosure... Yes, I have operated on occasion with that bunch, and have generally found them to be a welcoming, polite bunch.  But they have their limits to tolerating deliberate "principled" QRM when there is usually plenty of room down there.
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Jay -- N0FB, Elmer

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Norm, it may be only a guess, but I think that we Flexers notice it more because we have an extra sensory input,  our Panadapter/waterfall.  

It frustrates me greatly to see these types of folks taking 5-7 KHz of precious band space (and at QRO power) to discuss the minutia of the day.  What a better reason for the adoption of FreeDV or the like.  1.3 KHz versus 2.7, 3.0, 4.0, or 7 KHz with clean communications quality audio just make sense (where practical).
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Norm - W7CK

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I think your correct there Jay.  If it wasn't for the panadapter, I would most likely never know....  

Something interesting though.  When I'm listening to someone that is running 6Hz or more wide and I narrow my filter down to 2.7, 2.9, or 3.3 I really don't notice that much difference in audio quality.  Twice the bandwidth really doesn't necessarily equate to a proportional improvement in audio quality.

Has anyone else noticed that listening to a 6Hz + signal and switching between 6Hz and 3Hz on the receiver doesn't really make THAT much difference in audio quality?
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Jim - N7CXI

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It depends on your ears. For some, that extra bandwidth is like night and day. For others it's anti-climatic.

At the end of the day, those that deliberately cause QRM are objectively in the wrong. It IS legal to run 6kHz ESSB, it is NOT legal to deliberately cause QRM. What any individual prefers or finds important is secondary to the actual regulations.

... and I don't run 6kHz ESSB. I do, however run 3kHz and find that's the best trade-off for the groups I usually gab with.

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Ken - NM9P

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Of COURSE you won't hear any difference when you listen to an ESSB signal with your filter in the narrow position. You only will get the extra fidelity and sibilants information if you listen at the same bandwidth.

It is the same thing when you listen to a 3 KHz wide signal with a 2.1 KHz filter. You are just not going to receive the voice frequencies that are being transmitted. That is why a great sounding 3 KHz wide signal sounds "pinched" when you use a much narrower filter.

But If you have good signal strength and high fidelity speakers or headphones, it can make a very noticeable difference. There is less listening fatigue, and intelligibility is increased. I wouldn't recommend it for the middle of 20 Meters, but there should be a place where the audiophiles can exist unmolested, just the same as the AM ops.

Not to continue to hijack this thread, I suggest we can continue this discussion on a different thread.
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Norm - W7CK

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Yeah Ken.  I was listening with my filters set all the way up to 6-7Hz and then adjusting them down to say 2.7 to 4Hz.  It made a bit of difference, but not as dramatic as I would have expected.  My unscientific and to my ears only conclusion was that 3Hz wide seemed to be perfectly fine and the folks with good audio, sounded great regardless of weather they were transmitting 3Hz or 6Hz wide.  I was using a good headset at the time.  It was really interesting - I've actually heard many folks with great sounding audio transmitting 3Hz wide that sounded every bit as good as some of the ones I observed on 80m transmitting ESSB.  I'm not really griping, just an observation....
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KM6CQ - Dan

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I have experimented  with ESSB for quite a while. The audio is much better as long as the op EQ's it to sound like a natural voice.  (To much low end is the tendency) however one of the trade offs is it brings in a lot of hash on the band, unless your listening to a 30 over signal. I prefer to have my RX filters around 2.7 and TX about 2.9 For myself this is less fatiguing and sounds cleaner. I think that keeping your TX filters less then 3 kHz wide is more efficient.

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Jay / NO5J

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I start my RX filters at 200Hz in SSB, it keeps the subwoofer from walking around the shack.