Topband: The use of digital modes on 160 metres

[Jim Brown]

On 9/16/2012 12:25 AM, Tom W8JI wrote:
> I'm not endorsing or objecting to the concept of digimodes on 160 
> meters, but whatever happened to the ARRL bandplan?

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.

>
> Our region sets digital modes as 1800-1810.

Yes, but digital operators want to work DX too.

> 1835 up though around 1840 is used by CW as a DX CW work when the band 
> is busy. I often try to stay above 1835 on CW during European 
> propagation times to stay out of other people's hair when the band is 
> very good and crowded with stations.

This may come as a surprise to many, but those JT65 signals have been 
clustering between 1838.5 and 1840.5 for quite a while, but the only 
time anyone seems to be aware of them is when someone TALKS ABOUT THEM, 
not from any QRM they might cause. More to the point, I can go for DAYS 
without hearing more signals on 160M than i can count without taking my 
shoes off, so a better question is, what's the problem?

>
> 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. 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.  IMO, dirty CW and SSB rigs running 1.5kW (and more) are a 
FAR greater problem, and these lids NEVER clean up their act.  Have you 
forgotten your own crusade against clicks from the FT1000-series 
transceivers that persisted through several model "upgrades?"  Have you 
never turned your receiver on during a DX contest?

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.

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

73, Jim K9YC