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The exclusive amateur
shortwave bands are anything
but exclusive. Non-ham
intruders are a constant
threat, creating QRM and
making DXing and especially
weak signal working a misery.
Here are just a few of the
ham band intruders spotted
and in some cases identified
recently from the South
Pacific:
- A
VK/ZL propagation radar
accidentally system
QRMing 30 and 20m (more
below)
- A
carrier with 60Hz
sidebands sitting on
14000 kHz, located
somewhere to the North
East of ZL
-
Commercial broadcasters
from P5, BY, ET and
elsewhere, broadcasting
mostly on 80m and 40m
-
Pirate fishermen from 4S7 and villagers in YB using ham equipment (presumably) to chat to each other using SSB on various ham CW segments on 5kHz channel spacings
-
Illegal CBers
transmitting nasty AM and FM signals on the high HF bands, at times wiping out ham beacons
- The
dreadful Buzzsaw Over The Horizon Radars (OTHR) from BY (~43 pulses per second), 5B4 (~50 pps) and/or F, that wipe out great chunks of prime shortwave ham spectrum at peak DXing times, similar to the Woodpecker once broadcast from a massive antenna array near Chernobyl
- The
swish-swish washing
machine noises made by wave radar (called CODAR), often accompanying OTHR
- RTTY and other data-mode intruders, including a curious 10 kHz-wide fog
horn, various encrypted/indecypherable data signals and, um, a Dalek
- Gurgling water 17m harmonic/spurious mixing product of a CO (Cuban) broadcaster on some lower band
-
Dotters, channel markers, fishing buoys, licensed or unlicensed pirate beacons typically sending curious callsigns or strings of single letters such as N N N N
 , T T T T or E E E E or V V V V from various locations around
the globe ...
A technical configuration issue with the TIGER experimental propagation
monitoring radar system demonstrates the value of Intruder Watch. Hams
noticed and started complaining about what sounded like data mode
transmissions particularly in the 30m band and sometimes on 20m too. Through
the Google group (more below), we started working as a team to investigate the
source. The direction was hard to pin down but seemed to be roughly South or
West of ZL, an unusual direction for any short path signals! Eventually, the
intruder was traced through the TIGER website which conveniently reports the
frequencies being scanned, and sure enough the radar was spending a fair bit of
time in the 30m band. The 30m band is not an exclusive ham band so we have
more limited options than with, say, 20m but investigating the TIGER system
further led to the discovery that their license forbids interference to other services,
in other words they are not a primary user of 30m either. Contact with the TIGER
team led to the equipment being checked and the problem being traced to a
configuration option that was supposed to prevent transmission in the 20 and
30m bands but had somehow been lost. The system was taken off-air for most
of a day and reconfigured to skip the ham bands (plus guard bands on either side)
and peaceful DXing resumed on 20 & 30m - a good result all round! Thanks to
the Intruder Watchers and TIGER team for responding so positively.
Additional soundbytes of intruders and QRM sources on the IARU Region 1 website
helps identify commercial data modes etc. Another site has audio samples of
many ham and commercial data transmissions and the Fldigi website even has sample waterfalls to accompany the soundbytes.
I run a Google Group (email reflector) for Australasian and South Pacific hams to
report and share information on ham band intruders affecting IARU Region 3.
All
Australasian hams who are concerned about non-ham intruders on the
amateur bands are welcome to join the group
, earwig for a while to find out
how it works and then hopefully contribute details of intruders such as the times
(plus durations if possible) and frequencies heard, MP3 recordings (most of us use
Audacity with the Lame plugin to make MP3s), waterfall spectra, signal strengths
and ideally directions, or perhaps just a note about other identified signals heard at
the same time.
Current and former IARU Monitoring Service people belong to the group and
frequently share their wisdom and knowledge with us, for example helping us
identify stations or give us tips on how to DF (Direction Find). As an example, I
wrongly assumed curious mis-timed CW signals in the SSB segment of 20m were
intruders, but most likely they were legitimate Wabun Morse sent by ancient JA
hams using hand keys, evidently. Far from being intruders, these are historic ham
masterpieces!
Listings of shortwave intruders (plus some legitimate users such as the NCDXC
propagation beacons!) that have been professionally DF’d and identified are
published once a quarter by the ITU: here are the lists for Q1 2009, Q2 2009 and Q3 2009.
Unfortunately, irresponsible, incompetent and intolerant hams create a lot of QRM
too, such as this outrageous behaviour heard on a DXpedition station’s TX
frequency when someone quite rightly complained about their pileup wiping out a
maritime net monitoring for news of a South Pacific tsunami. It’s a sad sign when
somone can set up a website to name-and-shame the ham QRMers, pirates and
lids, including sometimes placeholders ready and waiting for the next big
DXpedition ...
DXpeditioners often jostle for position at the bottom ends of the bands on CW, or
on the usual RTTY and SSB spots further up, causing chaos when their pileups
mingle. Partly this is down to the DXpeditioners who choose the listening
frequencies they announce and where they actually listen (not necessarily the
same places!) but mostly it is caused by over-excited and inconsiderate DXers
who fail to listen on their TX frequencies. Frequency cops who berate them on the
same TX frequencies just make the problem worse since the offenders evidently
aren’t listening on their TX frequencies (doh!). For more advice on how to reduce
this self-made ham problem, look here.
Lastly there are the rude, ignorant and selfish hams who just keep right on
calling, regardless of any instructions to the contrary. This is quite a different
situation to those who make the occasional mistake, call out of turn or on the
wrong frequency. Good operators don’t make mistakes very often, and
immediately correct themselves as soon as they realise. The deliberate QRMers
don’t stop, even when everyone else understands and obeys the instructions. If
they behaved like this face-to-face in person, interrupting conversations by
shouting their names over and over, they’d get a bloody nose but, presumably
feeling safe and secure behind their transceivers in some far-off land, they
evidently think it acceptable to stamp all over polite operators, doing their level
best to spoil everyone’s fun. The thing is, every time they send their callsigns,
they identify themselves to everyone listening as obnoxious cretins. “
LISTEN TO
ME! I’M AN IDIOTIC LOUD-MOUTHED THUG!
” they shout to the whole world,
while quietly we record the evidence and DF them ...
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