Topband: The use of digital modes on 160 metres

[Tom W8JI]

> 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