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[hfsig] Re: [Flexradio] The final nail in the coffin of Morse ?

Walt DuBose dubose at texas.net
Sat Jul 23 06:44:50 UTC 2005


Bob,

I have to agree with Jeff.  I don't think the Board's intent was for anything 
but legacy AM voice having 9 KHz bandwidth...certainly not data...especially not 
data.

I believe that when the actual proposal is published, it will specifically allow 
only legacy AM voice to have 9 KHz bandwidth and all other modes must be not 
more than 3.5 KHz wide.

The problem is "...Since OFDM - fade designed trellis QAM seems like AM to me 
anyway."  If the Board doesn't see it that way and sees that 9 KHz bandwidth 
only applies to a legacy AM voice transmission, then you are stuck with 3.5 KHz 
bandwidth.

I hate like heck to throw cold water on you notion; but, I'm afraid that the 
Board didn't intend for the a 9 KHz bandwidth signal to be anything but legacy 
AM voice and their proposal will have the exemption specifically for legacy AM 
voice and thus all other modes are stuck to 3.5 KHz bandwidth.

Specifically, the ARRL prosal will follow this thought process...

	"The regulation-by-bandwidth issue dominated the Board's second meeting
	of the year in Windsor, Connecticut. After a great deal of give and take
	among its members, the Board ultimately okayed raising the maximum
	bandwidth the EC had proposed for frequencies below 29 MHz from 3.0 kHz
	to 3.5 kHz. A provision permitting the continued use of double-sideband
	AM with bandwidth of up to 9 kHz was retained."

	"Significantly, the Board also agreed that maximum permitted bandwidth
	should be defined in terms of necessary rather than occupied bandwidth.
	In addition, the modified proposal removes the exception for independent
	sideband (ISB) emissions--apparently not used in the Amateur Service--
	and drops certain mode restrictions on Novice and Technician class
	operators."

	"The ARRL proposal would leave two important FCC rules unchanged.
	§97.307(a) says: "No amateur station transmission shall occupy more
	bandwidth than necessary for the information rate and emission type
	being transmitted, in accordance with good amateur practice." §97.101(a)	
	reads: "In all respects not specifically covered by FCC Rules each
	amateur station must be operated in accordance with good engineering and
	good amateur practice."

So what then?  On the one hand the Board says the bandwidth will be no more than 
3.5 KHz except AM which can be 9 KHz wide and then says that no transmission 
shall occupy mode bandwidth than necessary for the information rate and emmision 
type being transmitted.

So is OFDM a transmission type?  What does "No amateur station transmission 
shall occupy more bandwidth than necessary for the information rate and emission 
type being transmitted" really mean?  Ok so perhaps this is the outlet.

So if my OFDM data transmission required 15 KHz to transmit 50 Kbps, is that OK?

IMHO the only thing to do is to start now and write our own proposal to the FCC 
in a technical yet easily to understand format.  A real challange...technical 
yet easily to understand.

We are going to have to "one up" the ARRL so than any proposal they present will 
seem like (because it will be) a proposal that doesn't advance technology and 
the state of the communications art, rather one (ours) that promotes 
experimentation in the advancement of the communications art.

The case must be clearly made that in data communications that increased 
throughput and robustness will require bandwidth wider than 3.5 KHz and it will 
be necessary to define high-speed and robustness as well as show, through the 
use of live (on-the-air) demonstrations or computer modeling/channel simulation 
the superiouity of any new mode or types of modes.

My greatest fear in all this is that it will NOT foster further development or 
the need for SDRs.  If this is true (with the passage of this sort of 
restrictive bandwidth as the League is proposing), then we can show that the 
League's proposal is NOT advancing the state of the art, rather preventing 
experimentation and advancement of the state of the communications art.

On 23 Jul 2005 at 12:46 AMBob wrote:
 >I don't think 9 Khz would be widely tolerated without a specific say so.  I am 
 >not talking about theoretical legal limits.   I could put a 200 Khz wide 
signal >on 20 meters in a few seconds by reaching over and turning on my FSK 
 >transmitter on my Gnu Radio USRP and it is likely no one would even know I was 
 >there.  I am talking about "officially sanctioned" or blessed operations of 
the >type (say) Walt could take and put into ARES, RACES, FEMA, etc. sites.

And yes, the proposal needs to be a recognized mode that we can present to and 
to be used by ARES, Red Cross, FEMA, etc.

I believe that this will take the concerted effort on many individuals part to > 
make a bandwidth proposal to the FCC.

73,

Walt/K5YFW


Jeff King wrote:
> There is effectively no bandwidth limit for OFDM modulations on HF as we speak, 
 > other then they be documented so not clear to me how the ARRL proposal will
 > cause anyones dreams to come to fruition.
> 
> On Sat, 23 Jul 2005 02:28:49 +0000, Robert McGwier wrote:
> 
>>You know my feelings already.  These suggestions will enable real HF
>> modems for the first time.  I would not  have dreamed of building a
>> reasonable HF modem until the League proposals were brought
>>forward.  It would have just been a waste of time.  I would have
>>been run out of amateur radio for even suggesting doing MS188-
>>110A,B, etc.  on (say) 20 meters in the phone band.  Now I can see
>>doing some serious work and it actually could be interesting at
>>last.  We could have 19-50 Kbps NVIS modems kicking some real butt
>>in 9 Khz bandwidth.  Since OFDM - fSince OFDM - fade designed trellis QAM seems
>>like AM to me anyway.  ;-). ade designed trellis QAM seems
>>like AM to me anyway.  ;-).   Imagine having really serious digital
>>voice over NVIS channels with S9 signals on 40 meters and running 5
>>watts.  Bring it on!
>>
>>
>>Bob
>>
>>
>>
>>DuBose Walt Civ AETC CONS/LGCA wrote:
>>
>>
>>>First, the NPRM was not strictly an ARRL proposal, in fact, it
>>>didn't appear to me to be the major proposal or proposal that the
>>>FCC used to draft the NPRM.
>>>
>>>Ok Bob, we know your views on CW, which are similar to my feelings,
>>> but what about the Board's decision to limit HF bandwidth to 3.5
>>>KHz with a 9 KHz exemption for AM?  Don't we need wider bandwidths
>>>for high-speed, robust data modes?  Isn't the bandwidth limitation
>>>going to be a greater factor in hingering the growth of amateur
>>>radio than the Morse Code issue?
>>>
>>>Walt/K5YFW
>>>
>>
>>
>>
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