[GreenKeys] FCC substitutes bandwidth limit for baud rate limit on HF

[John Vendely]

The NPRM proposes to substitute bandwidth limitations for the present 
symbol rate limitations.  This suggests it applies only to data 
transmissions, as symbol rate has no meaning in analog voice systems.  I 
must admit that I haven't scoured the document either, but BW of SSB and 
AM analog voice modes appear unaffected--at least for now.  Perhaps some 
reasonable BW limits are worth considering for these modes, as well.  Is 
it really necessary for AM operators to occupy 10 kc or more of 
spectrum, as often occurs?  Or "enhanced" SSB operation with 4-5 kc BW?  
A 3 kc BW per sideband would not be unreasonable for both these modes. 
Military and commercial AM gear was traditionally so limited.  No doubt 
this would result in a pitchfork rebellion from AM and "ESSB" operators, 
so the status quo will probably continue for some time.

BTW, I would suggest a data mode BW of 3 kc, rather than the proposed 
2.8 kc, since 2.8 kc would rule out a number of existing commercial and 
military data modes that could be very useful in amateur work, 
especially for emergency liason with other agencies...

73,

John K9WT

On 11/15/2023 1:01 AM, Richard Knoppow wrote:
> Perhaps someone here understands this better than I do. Does the 
> bandwidth limitation apply only to digital or data transmission or to 
> all transmission, such as SSB and AM?  If it applies to those it would 
> pretty much kill AM. I usually can make some sense of legal documents 
> but this one has stymied me.
>
> On 11/14/2023 11:53 AM, Harold Hallikainen via GreenKeys wrote:
>> They are substituting a bandwidth limit of 2.8 kHz for the previous baud
>> rate limit of 300 baud.
>>
>> https://docs.fcc.gov/public/attachments/FCC-23-93A1.pdf
>>
>> Looking at the new 97.307...
>>
>> § 97.307 Emission standards.
>> * * * * *
>> (f) * * *
>> (3) Only a RTTY or data emission using a specified digital code 
>> listed in
>> § 97.309(a) may be transmitted. The authorized bandwidth is 2.8 kHz 
>> except
>> in the 2200 m band and 630 m band. In the 2200 m band and the 630 m band
>> the symbol rate must not exceed 300 bauds, or for frequency-shift
>> keying, the frequency shift between mark and space must not exceed 1 
>> kHz.
>>
>> It looks like the 1 kHz shift limit is ONLY for the 2200 meter and 630
>> meter bands. So, can we run 2 kHz shift to get around selective fading?
>>
>> Further, the wording of that section appears to limit baud rate or 
>> shift,
>> but not both for those bands. Since those bands are quite narrow 
>> (135.7 to
>> 137.8 kHz and 472 kHz to 479 kHz), it's difficult to run very wide shift
>> or  high baud rate.
>>
>> Harold
>> https://w6iwi.org
>>
>
>