[RTTY] ARRL attack on current RTTY users

[Kai]

Thanks for the w8ji link. That was very instructional. But be careful. The 
signal occupied bandwidth (what we presume to want to regulate) does not always 
relate to the noise bandwidth (which relates to sensitivity).  JT65 fro example 
sports a noise bandwidth of about 2.71 Hz (yes, Hertz), but an occupied 
bandwidth of 175 Hz. Furthermore when operated as Joe Taylor intended at HF, you 
want to allow 2-4 kHz for JT65 users because multiple simultaneous users in the 
the 2-4kHz BW are decoded and presented to the user, just like in PSK31 (62 
Hz/user).

The ARRL proposal does nothing more than to remove the archaic and no longer 
relevant baud rate definitions of digital modes. They opted instead to propose 
regulating digital signals by a maximum BW, and chose 2.8 kHz to harmonize with 
the FCC/NTIA regulatikon already in effect for the 60m channels.

There are no changes to RTTY (which occupies 250 Hz per user at 170 Hz shift and 
45.45 baud - there are wider RTTY ham signals in use as well) or how RTTY is 
used in contests.

Today under the present baud rate restrictions we already hear digital signals 
as wide as 2,200 Hz in HF (PACTOR) and all is still right with the world.

The Canadian ham regulators already limit all emissions in HF bands below 28 MHz 
to 6kHz without regulating anything further about mode.

I think that discussion should center around what the BW limit shjould be for 
digital signals. The answer will likely be something between 2200 Hz and 2800 
Hz, because signals as wide as 2200 Hz are already permitted. It's good to 
discuss this.

73,
Kai, KE4PT



On 11/20/2013 9:42 AM, David Cole wrote:
> Al,
>
> Thank you for that link!  I now understand the dangers.