On Oct 15, 2021, at 15:29, Jerry Gaffke via groups.io <jgaffke@...> wrote:

The D-Star spec might be public, but it all seems rather murky.
As you say, it is implemented by buying something like that proprietary ABME chip,.
FreeDV, on the contrary, has code available that can run on a low end ARM processor.
That seems more in line with what Amateur Radio should be.
Clearly, opinions vary.

On Oct 16, 2021, at 10:01, Tom, wb6b <wb6b@...> wrote:

So are the folks experimenting with D-Star on HF just kind of flying under the radar?

Tom, wb6b

Hi Rafael

As Jerry said... It's a matter of optimization. Most currently popular
ham digi modes are sequential FSK modes (single carrier). FT8 accounts
for more digi mode activity than all the others put together. A good
SSB rig is a more complex and costly transceiver and that's what's
needed for multi-carrier modes.?

73 Hans G0UPL

The D-Star spec might be public, but it all seems rather murky.
As you say, it is implemented by buying something like that proprietary ABME chip,.
FreeDV, on the contrary, has code available that can run on a low end ARM processor.
That seems more in line with what Amateur Radio should be.
Clearly, opinions vary.

From Wikipedia:??

Proprietary codec? ?Like other commercial digital modes (,?,?,?,?,?), D-STAR uses a closed-source proprietary voice codec () that's patented by Digital Voice Systems, Inc. (DVSI)?because it was the highest quality and only codec available in silicon when the system was released. Amateur radio operators do not have access to the specification of this codec or the rights to implement it on their own without buying a licensed product. Amateurs have a long tradition of building, improving upon and experimenting with their own radio designs. The modern digital age equivalent of this would be designing and/or implementing codecs in software. Critics say the proprietary nature of AMBE and its availability only in hardware form (as ICs) discourages innovation. Even critics praise the openness of the rest of the D-STAR standard^[]?which can be implemented freely. As of 2017 the patents have expired, as announced by Bruce Perens, K6BP at the 2017 ARRL/TAPR DCC in his State of Digital Voice talk.

Would be interesting to see what Bruce Perens thinks about D-Star these days.
He's one of the original forces behind the FreeDV codec (didn't write it, but encouraged its development).

Jerry, KE7ER

On Fri, Oct 15, 2021 at 12:02 PM, Ken Hansen wrote:

The d-Star mode is open source, the chip that the two radio manufacturers use is proprietary, but it is only out of convenience that Icom and Kenwood use the AMBE vocoder. Just as Yaesu and Alinco use the same chip to implement C4FM and DMR

?

Of course, one would need to learn Japanese to read the D-Star specifications, but they are public, were developed by JARL, and are available for anyone to implement without license fee.

?

?

AMBE is just the audio codec (source coding), it has nothing to do with
the actual channel coding (modulation), right?

And indeed, AMBE patents already expired some time ago... and there are
some open source implementations hanging around for some time, eg:


For eg., freedv uses codec2 or LPCNet for audio coding.

The d-Star mode is open source, the chip that the two radio manufacturers use is proprietary, but it is only out of convenience that Icom and Kenwood use the AMBE vocoder. Just as Yaesu and Alinco use the same chip to implement C4FM and DMR

?

Of course, one would need to learn Japanese to read the D-Star specifications, but they are public, were developed by JARL, and are available for anyone to implement without license fee.

?

?

The d-Star mode is open source, the chip that the two radio
manufacturers use is proprietary, but it is only out of convenience
that Icom and Kenwood use the AMBE vocoder. Just as Yaesu and Alinco
use the same chip to implement C4FM and DMR

Of course, one would need to learn Japanese to read the D-Star
specifications, but they are public, were developed by JARL, and are
available for anyone to implement without license fee.


<>

Personally, the AMBE chip (at about $20 in single qty) seems like a
bargain compared with other methods of implementing D-Star, DMR, C4FM,
etc., but opinions vary.

I can buy an AMBE board for about $150 and 'operate' D-Star on my
windows PC w/o a radio (but what fun is that?):

<>


<>

That $150 board costs so much because it not only has the $20 AMBE
chip, but also a fair amount of other technology to support serial,
USB, WiFi AND Ethernet connectivity.

Ken, N2VIP

On Oct 15, 2021, at 10:19, Tom, wb6b <wb6b@...> wrote:

?
Hi,
?
I’ve ben doing a bit more reading on amateur radio digital voice
modes used on HF.
?
To focus on one possibility for a digital voice mode that may be
compatible with nonlinear RF finals, I discovered that D-Star is
being experimented with by some hams on HF.
?
D-Star uses GMSK, Gaussian Minimum Shift Keying on VHF/UHF. Best I
can tell the modulation mode is not changed in the HF world.
?
If so, this might be a way to add a voice mode to digital only modes
transceivers, with simple nonlinear RF output stages, like the QDX.?
?
D-Star uses a proprietary codec, so what I’d *suggest is use the
frequency shift (GMSK) modulation method but swapping out the D-Star
codec for the FreeDV codec.?*
?
Any major flys in the ointment here? Other than getting ham radio
operators interested in yet another voice mode?
?
There are, also, multiple frequency shift modes that might offer some
advantages. But GMSK seems the likely starting point for
experimentation or at least for this conversation.
?
I know there are folks that have gained much more knowledge of this
area than my beginnings at sorting through this area of knowledge.
Hopefully some of those folks will be able to add some practical
additional knowledge on the subject.
?
Tom, wb6b
?

On Oct 15, 2021, at 10:19, Tom, wb6b <wb6b@...> wrote:

?

Hi,

?

I’ve ben doing a bit more reading on amateur radio digital voice modes used on HF.

?

To focus on one possibility for a digital voice mode that may be compatible with nonlinear RF finals, I discovered that D-Star is being experimented with by some hams on HF.

?

D-Star uses GMSK, Gaussian Minimum Shift Keying on VHF/UHF. Best I can tell the modulation mode is not changed in the HF world.

?

If so, this might be a way to add a voice mode to digital only modes transceivers, with simple nonlinear RF output stages, like the QDX.?

?

D-Star uses a proprietary codec, so what I’d suggest is use the frequency shift (GMSK) modulation method but swapping out the D-Star codec for the FreeDV codec.?

?

Any major flys in the ointment here? Other than getting ham radio operators interested in yet another voice mode?

?

There are, also, multiple frequency shift modes that might offer some advantages. But GMSK seems the likely starting point for experimentation or at least for this conversation.

?

I know there are folks that have gained much more knowledge of this area than my beginnings at sorting through this area of knowledge. Hopefully some of those folks will be able to add some practical additional knowledge on the subject.

?

Tom, wb6b

?

Hi Rafael

As Jerry said... It's a matter of optimization. Most currently popular
ham digi modes are sequential FSK modes (single carrier). FT8 accounts
for more digi mode activity than all the others put together. A good
SSB rig is a more complex and costly transceiver and that's what's
needed for multi-carrier modes.?

73 Hans G0UPL

Exactly.? A non-linear power amp allows it to be optimized
for it's intended purpose.? It does not attempt to do everything.

If you need multiple simultaneous tones, there are dozens of
SSB transmitters you can choose from.??
But they won't be as cheap or as efficient with the power supply.

Jerry, KE7ER

On Wed, Oct 13, 2021 at 12:02 AM, Rafael Diniz wrote:

And why does this limitation exists? Because of the non-linear power
amplifier? Most of digital telecommunication these days are OFDM /
GFDM... always multi-carrier.

I believe section?97.307(f) of the FCC Rules still places a maximum symbol rate of 300 baud on emissions below 10 meters.

Hi,

?

I’ve ben doing a bit more reading on amateur radio digital voice modes used on HF.

?

To focus on one possibility for a digital voice mode that may be compatible with nonlinear RF finals, I discovered that D-Star is being experimented with by some hams on HF.

?

D-Star uses GMSK, Gaussian Minimum Shift Keying on VHF/UHF. Best I can tell the modulation mode is not changed in the HF world.

?

If so, this might be a way to add a voice mode to digital only modes transceivers, with simple nonlinear RF output stages, like the QDX.?

?

D-Star uses a proprietary codec, so what I’d suggest is use the frequency shift (GMSK) modulation method but swapping out the D-Star codec for the FreeDV codec.?

?

Any major flys in the ointment here? Other than getting ham radio operators interested in yet another voice mode?

?

There are, also, multiple frequency shift modes that might offer some advantages. But GMSK seems the likely starting point for experimentation or at least for this conversation.

?

I know there are folks that have gained much more knowledge of this area than my beginnings at sorting through this area of knowledge. Hopefully some of those folks will be able to add some practical additional knowledge on the subject.

?

Tom, wb6b

?

?