Well, the unidentified expert's statement is a bit extreme. PSK 31 is the result of digital experimentation and uses less than 200 Hz bandwidth. PSK 31 is popular because it allows communication at speeds that humans can originate and assimilate. If you want to transfer files and images you need faster data rates, and the sky's the limit.

The reason for 3 kHz -- which was in the original draft and attracted little negative comment in the initial round last August -- is simply that it's the maximum bandwidth that can be passed through a typical voice-bandwidth transceiver. If you are equipped for wider bandwidths, then you can pass data faster. The tradeoff is the impact of a single station on the other stations with which it shares the band. Maybe some other number is better than 3 kHz (the "anti-Winlink" folks clearly want an even lower number) -- but we need a number.

One of the reasons we need to revise the regulations is because the present rules don't provide any limit, or even any guidance, as to how wide a digital emission should be allowed in the HF bands. The guidance is there for analog modes, but (with a few limited exceptions) not for digital. When someone says "we don't need bandwidth regulations" do they really mean that digital emissions up to 50 kHz wide should be allowed in the 10-MHz band? Do they mean that amateurs should be allowed to use 10-kHz wide DRM, as the HF broadcasters are doing, in the phone bands?

If we do nothing, how many of the members who are now saying "Don't regulate by bandwidth" will be saying a few years from now "How could you have let this happen?"

My expert on the subject says that limiting digital bandwidth to 3 KHz will kill digital experimentation. (which is what I thought we were trying to encourage with this effort) He quotes laws of physics that balance robustness against throughput. He says that current modes are about as good as we are going to get with a 3 KHz limit. My degree is in math-physics and he is over my head. :-)

Hi Coy:

Yes, I've had one comment about that issue. It was from an individual that likes to pass traffic and is one of the long time NTS guys. I bounced the discussion around a bit and asked him some questions to try and better understand, specifically if he thought we needed a segment for that group, too, like we made for the automatic group (not semi-automatic). I asked him how many people would really need this provision given the digital scene today and after some more discussion, I was left with the impression very few.

In any event, it did leave me wondering. I asked him to outline his points and get it to me, but I have not heard back from him yet.

Like I said, that's the only comment I've received on that issue.

73,

Rick - K5UR

-----Original Message-----
From: n5ok.ok@att.net
To: arrl-odv <arrl-odv@reflector.arrl.org>
Sent: Wed, 04 May 2005 20:25:52 +0000
Subject: [arrl-odv:12268] 3KHz Wide Digital

If I understand the EC's proposal, the digital modes will be limitted to 3KHz at HF frequencies. I'm hearing from my digital experts that this isn't enough bandwidth to keep from severly limitting the data rates that can be obtained. Anyone else h! ! earing this?

Coy

--
ARRL West Gulf Division Director
Coy Day, N5OK
20685 SW 29th St
Union City, OK 73090
n5ok@arrl.org 405-483-5632