FROM IARU Website.
Beacon Interference
The major interference problem for beacon listeners occurs on the
twenty meter frequency of 14100 kiloHertz. The IARU/NCDXF beacons have
been on this frequency since 1979. The frequency was established
before the tremendous advances in the popularity of the digital modes
occurred and today the frequencies on both sides of 14100 kiloHertz
are full of digital signals.
On the ham bands, no station has a legal right to exclusive use of any
particular frequency. However, as the digital-mode signals began
encroaching on the beacons, both the IARU and the ARRL incorporated
into their official band plans the idea that the frequencies between
14099.5 and 14100.5 should be kept clear to protect the beacons at
14100.0. Although these band plans do not have the full force of law,
there is general agreement that a properly operated amateur radio
station should normally operate within such band plans and the vast
majority of digital operators do so.
If one listens for the beacons with a receiver whose bandwidth is
designed for voice reception, the 2.8 kiloHertz bandwidth typical of
such receivers will inevitably receive adjacent digital signals as
well as the beacons. When this happens, the resulting interference
should not be blamed on digital operators so long as their signals are
more than 500 Hertz from the beacon frequency.
It is recommended that when you listen to the beacons you use a
receiver with a CW IF filter of 500 Hertz or less. Such a narrow IF
filter is primarily needed to reduce interference from digital signals
on 14100 kiloHertz, but will help you to hear the beacons better on
all bands by reducing atmospheric and other noise.
Unfortunately, not all digital operators are familiar with fact that
the official band plan for twenty meters calls for keeping the
frequencies around the beacons clear. Furthermore, some digital
operators do not realize that their transmitted RF energy occupies
frequencies which are different from the frequency which shows on
their dial.
If you notice a station which is not abiding by the band plan and is
transmitting RF energy too close to 14100 kiloHertz, you may, in a
nice way, call that station's attention to the interference he is
causing. He probably doesn't realize he is interfering. It is ironic
that one such station was automatically forwarding DXing information
while simultaneously interfering with a major tool for DXing.
You are welcome to send interference reports to the Beacon Committee/a>.
In the typical case of a digital-mode interfering signal, the most
useful reports are from stations which can actually receive the
digital transmission and which include the time, the date, the
callsign of the transmitting station, the mode being used, and the
dial frequency used to monitor the transmission. It is also useful if
you include the IF bandwidth you use for listening to the beacons.
End....
--
Andy K3UK
Skype Me : callto://andyobrien73
www.obriensweb.com
www.myspace.com/k3uk
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