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Re: Topband: The use of digital modes on 160 metres

To: <topband@contesting.com>
Subject: Re: Topband: The use of digital modes on 160 metres
From: "Tom W8JI" <w8ji@w8ji.com>
Reply-to: Tom W8JI <w8ji@w8ji.com>
Date: Sun, 16 Sep 2012 14:20:52 -0400
List-post: <topband@contesting.com">mailto:topband@contesting.com>
Ever listen on Top Band during a contest? On a CW weekend, CW goes from 1800 to at least 1910 kHz, and on a SSB weekend SSB extends well below 1825 kHz.

A temporary operation during a few special events during the year has nothing at all to do with establishing a poorly planned regular operation.

Our region sets digital modes as 1800-1810.

Yes, but digital operators want to work DX too.

If that is the case, domestic-to-domestic operations should use a more reasonable frequency so as to not clutter frequency ranges for long distance work. 160 meters, I'm sure we will all agree, has no skip zones and does not weaken domestic propagation. This is why DX areas are so important on lower bands, and almost meaningless on higher bands (unless local ragchews are involved, like on six meters).

The problem with digital modes, in my opinion, is they often are not generated and decoded properly. They are generally audio baseband signals converted up to RF by a normal cheap transceiver's SSB chain, and converted back down through the SSB receiver.

Your opinion has little basis in fact.

It has an absolute basis in fact.

Anyone generating a dirty digital signal is going to get a bunch of nastrygrams from other digital operators and clean up his act pretty quickly. The reason is simple -- a dirty signal spews trash in the limited bandwidth (2 kHz) used by those digital modes, making life miserable for everyone in that bandwidth.

That isn't true. Many or most operators go by IM reports generated in the software, and those reports do not generally include hum, noise carrier suppression, and harmonic distortion.

Many times the digital op has a poor receiving antenna, which does not let him hear weak signals. My own receiving system, and I'm sure more and more stations as they upgrade to better systems, will let me clearly hear microwatt signal levels at first-hop distances, and in the low dozens of microwatt levels at second hop distances.

Harmonic distortion, hum, and noise levels from 100 watt SSB transmitter systems are well beyond the MDS of weak European signals, and cannot be detected without reasonable receiving arrays.

Collins thought they could get away with SSB mode generation of CW and caused huge problems.

Another point -- just as other non-contesters disappear from a band during major contests because they can't function, you're not going to hear guys running JT65 during a 160M contest. No way that they COULD! In all the years I've been working 160M contests, I've never heard them during a contest.

I sure have, but that isn't the point I was making. My point was selection of the middle of a weak signal area for SSB transmitters with various audio tone formats is probably not a wise choice. This is especially true when we run into the common human problem of denial and dismissal, rather than intelligently listening to both sides.

Bottom line -- the interference problems you raise simply don't exist. It's like most prejudices -- all preconceived notions with no basis in fact.

This is a very common human trait. We all, to some extent, dismiss something we have not heard and assume what we do not notice ourselves must not exist.

There are, however, socially acceptable ways of discussing things without insulting other people. My goal is to spend as little time as I can offending other people. I decided a few years ago the most valuable class I took was Kindergarten, where my teacher tried to encourage proper social interaction and to judge others as less than us.

Surely we can discuss things important to the bands like mature adults.

73 Tom
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