[CQ-Contest] Malicious Interference during SS

[Leonard J. Umina]

A lot of the interference I encounter is intentional, but its the 
contest operators who do it.

I've known certain ops who use rigs with bad CW keying intentionally 
because it "helps" them hold a perch.  It's not as common these days 
only because most rigs key well to a point (see below), but the FT-1000 
was notorious for bad CW keying.  These rigs were once sought after by 
some simply because being nearby in frequency to one running a perch 
with a KW was almost impossible.

Then there's the weighting ratio interference.  Most people know that 
bandwidth varies with information rate, and that a CW signal is wider 
based on speed than a dead carrier.  The other issue is that you can key 
most rigs faster than they can respond with nasty results - not nasty 
enough to prevent communication, just a wide signal with plenty of 
garbage that will make people keep away from your frequency.

That's why you hear so many contest stations with their dot width 
shortened to the point where the rig will barely key.  The data rate of 
the dots, combined with the radios inability to run at that rate, gives 
them a nice 'almost legal' signal that helps to hold the frequency and 
makes the signal stand out in a pileup.

Now for the compression on SSB.

Most good ops use compression, but many turn it up much further than 
they should and some don't know that there is any setting except all the 
way up (perhaps because the ALC meter isn't at "max" until they do it).  
Not only are these signals terrible to listen to, the splatter is really 
bad, especially when the band is open.

On SS SSB there were a few stations with big signals that were 
splattering terribly, and causing interference to the entire band across 
the entire USA (and likely the world for that matter).

I think the FCC should do 90% of its enforcement during SSB contests. 

No one should have to 'ask you' to turn your compression down.  
Presumably you operate your station once in a while (or someone does) 
before the contest, and thats the best time to make compression 
adjustments.  During the contest there are too many competing indicators 
(like QRM, other signals, and testosterone).  If you establish that a 
"4" or a "5" setting is good enhancement without distortion, then why 
set it anywhere else in a contest except to cause intentional 
interference....

Of course ARRL SS is one of the better contests.  The international 
contests are the worst and my country of origin was well known for 
generating some of the most heinous signals out of Europe.  In the past 
few years they have lost their title to the stations to our south 
though.  Perhaps it's just the propagation and they'll regain their 
title when the sunspots let us hear them more frequently!

Finally, there's the issue of receivers.  Most people don't know how to 
use them.  Even some of us who should screw it up, so its hard to 
"blame" anyone.  I got stung for most of the ARRL SS CW by not realizing 
my Orion's HW noise blanker was actually ON when I thought it was off.  
The resulting QRM in my radio was incredible - and it was all my fault!

Similar things happen without noise blanker issues.  Fundamental 
overload and operating a receiver outside of it's intended dynamic range 
and expecting "normal" performance is the primary culprit.  Lets face 
it, if your radio gives you great performance and selectivity for normal 
operation, that is NO INDICATION of how well it will work when every 
signal on the band into the first IF is running 20-60 db over S9!!  
Almost no radio can cope with this, even a lot of the expensive ones, 
unless they are set up correctly, and even an inexpensive radio will do 
a good job if it's operated correctly.

The key here is RF GAIN.  I've told thousands of hams the trick, but I'm 
going to repeat it here again.  Turn your audio up to 90% and use your 
RF GAIN control to control your volume.  That's it.  Simple.  I've said 
it so many times that my friends call it "Len's Law" but quite frankly 
it works and for good reason.  Your audio stages are designed and built 
to reproduce the decoded signals from your RF stages.  They typically 
have minimal distortion, even at full volume but 90% is generally very 
clean on any radio.

By running your audio up so high, you can reduce the gain of your RF 
stages significantly.  So much so in fact that your filters will exhibit 
the kind of operational performance you are used to.  Most filters have 
skirts and if a signal is strong enough you will hear it because there 
will be enough signal for it to be detected outside the usually observed 
passband of your filters.  The way to deal with this problem is to 
reduce the gain.

Incidentally this little trick works very well when the band is full of 
lightening crashes too.

I also find that attenuators are necessary when the band is open.  This 
may seem counter-intuitive, especially to the QRPers but if you try it 
you'll see that it makes little difference and so dramatically improves 
intelligibility that even the weak signals are heard.  For most of  SS I 
run at least 12 db of attenuation on 80 meters and frequently 18 db.  
While this may seem like a lot of attenuation it's really not.  It's 
about 3 S units, but what a huge difference it makes!

On bands where the signal strength is low (like 10 or 15 meters in 2008) 
this is not usually necessary, but trust me on 80-20 this makes a huge 
difference in receiver performance.   A lot of the low level "crud" that 
is up 10db thanks to amplification is now much lower in strength - and 
remember there's usually more crud than normal during a contest!

I consider 'intentional interference' from the transmitting stations to 
be the most obvious, but I also consider 'intentional interference' on 
the part of the receiving station to be just as bad and far more 
stealthy in nature when it comes to dealing with the problem.  Most 
operators need to 'get a clue' when it comes to operating receivers 
under the conditions of a major contest, and thats a fact - even many of 
the big guns have the issue.

Finally, while I'm on the soapbox here, I was just listening to a super 
station calling CQ TEST.   What a great signal!  The CQ was automated 
with such a short pause between repeats that it took me several calls to 
get the operator to realize that there was a signal there.  Several 
others had also tried in vain to get his attention.  Face it super ops, 
while putting RF out does hold your frequency and get attention you 
can't work em if you don't switch to RX long enough to hear them 
respond!  During SS I observed this type of operation at least a dozen 
times.

There is no substitute for a good receiver, and there are a lot to chose 
from.  I'm spoiled by my Orion where I can switch in roofing filters as 
narrow as 250 Hz and use the DSP to get to 100 Hz with no ringing.  
That's the brute force approach and it works, but most of my radios will 
work almost as well with an attenuator, audio up, and rf gain variable 
for listening as I've described.  Some don't, but even the Orion 
benefits when I'm not intentionally interfering with myself by using it 
properly - in fact using broader filters is almost essential if you are 
not doing search and pounce because most stations calling are off 
frequency - some decidedly so - so I use these techniques regularly.

In fact before closing, let me just mention that failing to zero beat is 
another form of "intentional interference".  In the cases sited in this 
thread, its also possible that a lot of the "observed" interference was 
not from the big gun, it was from the people calling him that were off 
frequency by several hundred Hertz - providing just enough out of 
channel signal that the nearby operator got QRM'd.  This folks is 
another "technique" in a pile up and when there's only 1 station 
operating from Newfoundland and you need it for a Clean Sweep, the pile 
ups can get pretty large.

You may not realize it when you use your transmitters XIT control to 
move your TX signal around, but you can be causing a lot of extra 
interference, and some people will blame the observed bleed through on 
the perch station because your signal is probably transient and his is not.

The ARRL could go a long way toward fixing this problem by making a 
minor change to the rules - if the section is not populated enough to 
field at least 5 stations during a contest then it should not be 
necessary to work it.  The 'problem areas' in Canada account for a lot 
of SS QRM by over anxious, frustrated, and hurried operators during a 
contest but that's somewhat off topic I guess.

73,
Len Umina
WT6G