[RTTY] Wow - thanks Dr Flowers!

[Joe Subich, W4TV]

 > < 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."

PACTOR III is not legal under those guidelines as SCS does not publish
(document) the data compression codes used to reduce common character
strings.

73,

    ... Joe, W4TV


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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