Bandwidth limits for ditigal modes (FCC)

[Rick, WA6III]

Howdy all,

ICYMI, it appears that the FCC will (vote to) propose bandwidth limits on digital modes at their next meeting on the subject (NOV 15)

If 2.8kHz (and other data rate)  limits are "changed" this should allow FreeDV to be used anywhere on any band or at least in segments previously set aside for digital modes etc.

I believe this would be pretty good for Digital voice because it should allow avoiding the current analog voice bands and subsequent interference etc.

It would also appear that D-Star HF use might then be limited to the voice bands because of it's bandwidth requirements....But I have not been able to find anyone that uses it

There will be a 30 day period for interested "parties" to comment, and while I still use CW once in a while, look for Morse Code proponents to claim the sky is falling.

Here's what one of the reporters said:

https://www.radioworld.com/news-and-business/business-and-law/fcc-wants-to-bolster-amateur-radio

Cheers,

Rick

[Mooneer Salem]

Hi Rick,

The current FCC proposal doesn't change anything about what constitutes "phone" or "data" or where either can be used on the band. Thus, FreeDV would still be relegated to the phone/upper halves of each of the bands where it's currently legal. Still, this is good news for anyone who's into data modes as the 300 baud limit has always been pretty arbitrary (and silly now that we're capable of higher speed data in smaller slices of bandwidth).

Thanks,

-Mooneer K6AQ

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[Alan Beard]

Hi Mooneer and Rick,

>the 300 baud limit has always been pretty arbitrary

Does this come from the WWII days well before DSP was even thought of?

Is this why there has not been a modem done for the 450 modes?

And my last question to the whole reader base:

As we know CTCSS tones on VHF/UHF repeaters "flag" whether this signal
should trigger a repeater. So, what flags are available  or proposed in the
Codec2 protocols to trigger such as a repeater?

0x73

Alan VK2ZIW 

[Mooneer Salem]

Hi Alan,

The symbol rate limit never affected the 450 mode since "voice" modes like FreeDV don't fall under that. I'm not sure offhand why 300 bps was chosen originally but the 450 mode was more of an experiment IIRC and is set to be removed from Codec2 as part of the ongoing cleanup and "universal" mode efforts.

Thanks,

-Mooneer K6AQ

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[Rick, WA6III]

Mooneer,

My main point here was that this could  result in rearranging the band segments and  narrow digital voice modes might be allowed due to their inherent bandwidth efficiency.

In any case, when anyone writes comments to the FCC during the 30 day period following the proposal,  be sure to mention that digitally encoded voice is STILL  a (narrow) digital transmission and therefore should  be allowed anywhere other digital modes are allowed.

They probably won't consider changing anything unless enough people ask them to. ("squeaky-wheel gets greased" etc)

Regards,

Rick

[G D]

First things first..  FreeDV is Voice not digital.  I am not sure why people seem to lack that understanding.  

[Rick, WA6III]

Ok, Digital Voice (ODFM/QPSK/BPSK/DQPSK)  is not "digital" ......Got it!

But it doesn't matter.

What matters is the FCC,  a regulatory body is about to change from the 1950's style of frequency management to something a little more modern!  I.E transmission bandwidth instead of actual mode for a Hobby/Experimental "service" 

Aside from the fact that there should be little or no controls (other than the current prohibitions on interference, intentional or otherwise)   on the Amateur Radio Service with regard to mode of operation vs frequency there is an opportunity to make some changes that just might benefit us all.

 "Digital" voice modes are vastly different from the current ancient analog voice modes like single/double/ independent sideband with suppressed, reduced or pilot carrier and/or single & double sideband FULL carrier AM,  and of course, FM & PM.  

It just makes sense to move narrow digital data modes (and narrow "Digital Voice" modes) to a separate segment of the band due to their inherent narrow band characteristics.....They already did it with "Digital" data modes.

It would seem the ARRL and/or maybe other groups want to put all voice modes,  digital or otherwise into 1 box (or segment)

This might be the time to "lobby" for a segment for digital voice modes.....  Like FreeDV, D-Star, "Digi-Babble" or some other future (narrow)  mode not cooked up (yet)  

Just thinking out the box here!

I think "we" as interested parties should make those types of suggestions when the comment period starts.

Cheers,

Rick

[Mooneer Salem]

Note that the comment period that will be coming up after this is approved at the November meeting (assuming it is in fact approved by the majority of the FCC commissioners) only deals with what the bandwidth limit should be for VHF/UHF, 630 and 2200 meters; comments about anything out of scope might simply just get ignored. I'd suggest talking to the ARRL and expressing your desire to go to a full "regulation by bandwidth" model.

(I mention ARRL because they may be hesitant to try again due to what happened the first time they proposed something like that. Hint: read about what happened with RM-11306.)

-Mooneer K6AQ

[Mooneer Salem]

I don't think a separate subband just for DV is the right approach. Theoretically FreeDV *should* be able to coexist with other users, especially since we're listening before transmitting...right? (I really hope people are, anyway, as intentional interference is one of the things frowned upon by the FCC.) 

Plus, even if it does turn out that we should get a separate area, I would think we could do that via informal band plans rather than enacting new regulations so we don't end up in a situation similar to the 300 baud thing. Of course, I could be way over-optimistic about that, too.

-Mooneer K6AQ

[John D. Hays]

The regulations prohibit harmful interference which has a specific definition, not all or any interference.

[Tony Langdon]

From an outsider's point of view (and eternlaly frustrated by the
fallout from US regulations), I fully support the proposal to remove the
baud rate limit and advance US regulations to the *ahem* 1990s. ;)

In the future, I'd like to see the FCC and the hams themselves actually
trust US hams to work out band plans as voluntary agreements for
amateurs to work within, just like we do here (and much of the world does).

To me, asking for a FreeDV segment from the FCC is only perpetuating the
silliness that exists now.

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73 de Tony VK3JED/VK3IRL
http://vkradio.com

[Alan Beard]

Re: The 450 modes

Though standards are a good thing, this limits experimentation.

Note guys, the TWELP (c) protocol has a 300 bits/sec mode now!

So, let's not lose the 450 modes in the Codec2 library even if they are

not included in the FreeDV app.

My 2c.

Alan VK2ZIW

[Brian Morrison]

These modes are not lost, the source code still exists and anyone can
create a library that contains a codec mode that makes use of it.

It's usually a bad idea to leave code that is not actively
used/maintained in a 'production' library as it can have unexpected
effects especially in embedded processors with limited code space.

--

Brian G8SEZ

[Mooneer Salem]

Hi John,

Per Part 97, it seems fairly obvious that the standard is simply intentionally interfering with other hams, not necessarily only "harmful" interference:

§ 97.101 General standards.

...

(d) No amateur operator shall willfully or maliciously interfere with or cause interference to any radio communication or signal.

Regardless of what the FCC thinks, though, it's not really a good idea to transmit if you hear someone else simply because it's the polite thing to do (much like life off the air).

Thanks,

-Mooneer K6AQ

On Sun, Oct 29, 2023 at 9:41 PM John D. Hays <jo...@hays.org> wrote:

The regulations prohibit harmful interference which has a specific definition, not all or any interference.

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[Tony Langdon]

I'm inclined to agree, why should we lost the 450 bps Codec2 mode? Frim
what I understand, there's no technical or legal reason to drop it.

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