[RTTY] Wow - thanks Dr Flowers!

[Kai]

Dave
There is no world in which baud rate limits bandwidth. Bandwidth may depend on 
baud rate a a bunch of other things, but limiting baud rate does not by itself 
limit bandwidth.
73
Kai, KE4PT

On 12/26/2013 4:42 PM,  Dave AA6YQ wrote:
>>>> AA6YQ comments below
> -----Original Message-----
> From: RTTY [mailto:rtty-bounces at contesting.com] On Behalf Of Kai
> Sent: Thursday, December 26, 2013 3:16 PM
> To: rtty at contesting.com
> Subject: Re: [RTTY] Wow - thanks Dr Flowers!
>
> Hi Al,
> Baud rate does NOT limit BW, except for 2-tone FSK RTTY.
> Actually, two tone FSK RTTY is the ONLY digital modulation that currently has a defacto BW limit under FCC rules. Those limits are
> 300 baud and 1000 Hz maximum spacing between tones, which would occupy 1500 Hz. No one uses that, but it is a limit.
>
> On the other hand, I can legally use, for example, 16 carriers (or 32 or 64) spaced 1 kHz each, with each carrier containing QAM
> encoding, and as long as I strobe the ensemble of those carriers at less than 300 baud, I'm legal - and occupying more than 18 kHz
> (or 34kHz or 66 kHz) BW.  It's a crappy modulation but LEGAL today! The FSK shift limit doesn't apply because it's not FSK!
>
> The ONLY thing limiting modulations like the crappy ones I listed above is that VERY FEW receivers out there can handle a bandwidth
> of 18 kHz (or 34 kHz or more).  Most radios can handle less than 2400 Hz of phase and amplitude-linear BW suitable for modern
> modulations.
>
>>>> Thus in the real world, where  HF transceiver passbands have finite widths, baud rate limits bandwidth.
>
> PACTOR-4 (which occupies about 2200 Hz BW, just like PACTOR 3 which is in use today) would indeed be permissible once the 300 baud
> symbol rate is removed.
>
>>>> If the ARRL petition is accepted, Pactor 4 would only be permissible if it is publicly documented as the ARRL describes here:
> <  http://www.arrl.org/technical-characteristics>
>
> " Documentation should be adequate to (a) recognize the technique or protocol when observed on the air, (b) determine call signs of
> stations in communication and read the content of the transmissions."
>
>          73,
>
>                   Dave, AA6YQ
>
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