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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
sprog/mixing product on
1908kHz from two
commercial MW AM
broadcast stations in ZL
- A pirate using the call ZL9BI on 30m CW and calling himself “Tom”,
believed to be in the
vicinity of ZL but not
due South where Auckland
and Campbell Islands are
...
- Fishing buoys transmitting on 10m from somewhere on an Easterly bearing from ZL
- 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 segments with roughly 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 and elsewhere (including the phantom
pharter at ~80 pps) that wipe out great chunks of prime shortwave ham spectrum at peak DXing times, similar to the bone-crunching 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 Cuban broadcast station on some lower band
-
Dotters, channel markers, fishing buoys, licensed ham beacons 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.
Given the popularity of
soundcard digital modes among
amateurs, it’s often
hard to figure out whether a
given jangly noise on air is
a legitimate ham digital
transmission using an obscure
or new mode, or a commercial
intruder.
Unfortunately, although some
digital modes software
supports several modes,
decoding unknown signal types
is often impossible without
knowing the precise ode i.e. the bandwidth, number of signal frequencies, speed of transmission etc.
Sometimes the band frequency
used is characteristic, but
mostly we rely on the
characteristic sounds of the
different modes to identify
them by ear. Soundbytes
of intruders and QRM sources on the IARU Region 1 website help identify commercial data modes etc. Another site has audio
samples of many ham and
commercial data transmissions, and here’s another good one,
while the Fldigi website also
has sample waterfalls to accompany the soundbytes.
For what it’s worth,
the most common digital modes
on the HF bands are probably
RTTY
(45.5 baud, 170 Hz shift) and
PSK31, plus Olivia
(either 16 tones within a
500 Hz bandwidth or 32 tones
within a 1000 Hz
bandwidth) and JT65
(particularly on the WSPRnet frequencies). To hear what these signals sound like, tune through 14060 to 14110 kHz whenever 20m is open. RTTY signals will often be heard around 14080-90, PSK31 clustered around 14070, Olivia around 14076 or 14107, and JT65/WSPRnet around 14095. There are also
SSTV
signals on or near 14230.
Tip: check the Hamspots website to find who is currently active on what modes and frequencies.
I am the deputy Monitoring Service Coordinator for NZART’s Monitoring Service,
supporting the main man John
ZL1GWE.
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. It all
helps. Information on
intruders is collated from
the reflector and other
sources to contribute to the
IARU Monitoring Service
reports, and to persuade the
authorities to act on clear
infringements.
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, and similar indecipherable code on 7015kHz one ZL evening, 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! Each Wabun character is a Japanese kana, with the Wabun transmissions starting with the DO prosign. Fascinating stuff.
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.
Read how modern
software-defined radios are
used to interpret complex
signals received by antenna
arrays for professional, if
not amateur HF direction
finding purposes.
Use one of the web-enabled
SDR to cross-check any QRM
you find, for example this Dutch SDR.
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, or a LidList ...
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 as obnoxious cretins to everybody listening. “
LISTEN TO ME! I’M
AN IDIOTIC LOUD-MOUTHED THUG!
” they shout to the whole world, while
quietly we record the evidence and inform the authorities <cue evil laugh>
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