ARLA/CLUSTER: Plano de Banda da IARU Região 1 para HF - Como interpretar? por Ulrich Mueller (DK4VW) Presidente do Comité C4 da IARU Região 1 para HF

[João Costa > CT1FBF]

IARU Region 1 HF bandplan – how to interpret?
Ulrich Mueller, DK4VW, Chairman IARU Region 1 HF Committee C4

After amateur radio was recognized as a service at the first World Radio
Conference in Washington (DC) 1927 and had some HF bands allocated, the
amateur radio societies agreed to suggest recommendations on how to use
them.

In the beginning the bands were divided only in sections for telegraphy and
telephony; in the 1960s Radio Teletype (RTTY) and later other digital modes
(Packet, Amtor) were added. In addition to the segment for RTTY, a specific
segment for Packet Radio was introduced into the bandplan; however packet
turned out to be rather unsuitable for HF and is rarely used. All the
different digital modes that were developed and used for some time for
experiments caused the HF managers of IARU Region 1 to think about a method
to react more flexibly to mode changes.

Should each IARU Region 1 conference, which takes place every 3 years,
modify the bandplan in favour of a new digital mode and delete the out
dated ones? The solution found was to divide the HF bands into segments
with a different maximum of occupied bandwidth for the specific modes:
segments with max. 200 Hz, 500 Hz, 2700 Hz, and in the 10m band
additionally with max. 6000 Hz bandwidth, plus a small segment with max. 20
Hz on the 5 MHz band.

Up to the maximum bandwidth all modes should get access to the specified
segments with equal rights. A bandplan following this philosophy was
introduced for the first time by the Davos conference 2005.

The bandplan shows these columns: Frequency, Max. Bandwidth, Preferred Mode
and Usage.

Segments with 200 Hz maximum bandwidth:
Normally only CW is named in these segments, with the exception of a small
10 kHz segment on 80m, where digimodes are preferred. If CW is shown as
preferred mode, then only CW mode should be used. In fact this is in
contradiction to the basic bandwidth philosophy, but there are historical
reasons for this singular exception: It is intended to separate CW
operation from the digimodes which are generated and decoded by computers
and therefore might not recognize weak CW signals.

Segments with 500 Hz maximum bandwidth:
These segments are intended for all narrow band modes not exceeding 500 Hz
bandwidth. In practice these modes are all digimodes (RTTY, AMTOR, JT65,
PSK31 etc.).

Segments with 2700 Hz maximum bandwidth:
All modes with up to 2700 Hz bandwidth may be used; such a maximum
bandwidth is needed for SSB or digital modes transmitting text, image or
voice. The bandwidth of a normal SSB filter has set this upper limit of
2700 Hz. Such a limitation should allow usage of the band by as many
stations as possible with an equal fraction of a band, independent of mode.
In the past we had no limitation of bandwidth indicated in the bandplan,
but the introduction of such limitation is justified by the increasing
number of radio amateurs during the past decades.

A digital voice or image mode could occupy up to 10 kHz running to full
efficiency; in the former 40m
band only 100 kHz wide, a few of such QSOs would block the entire band
Europe-wide, which is not
acceptable.

Segments with 6000 Hz maximum bandwidth:
Modes with up to 6000 Hz may be used on frequencies above 29000 kHz, since
the 10m band is wide.
In practice such a bandwidth is used mainly for FM transmissions with a
very low modulation index.

Explanation of “Preferred Mode and Usage�:
Centre of Activity
These are frequencies on which certain activities, like QRS or QRP, should
concentrate. They are
mostly derived from practice and should advise where somebody with the same
interest can find a
QSO partner more easily. Indirectly such a note is a recommendation to
those with no interest in the
special interest to avoid this frequency for calling CQ. In the sense of
good self regulation of the
amateur radio service everyone should keep this in mind.
Nobody may claim to use a specific frequency or one around it, a centre of
activity may not be
interpreted as a frequency reserved for an interest group. If such a
frequency is already occupied, one
has to move some kHz to the next free frequency, which is the standard
procedure for the entire
band.

Digimode
Some parts of a segment with a max. bandwidth of 200, 500 or 2700 Hz
indicate digimodes as the
preferred mode. This is another recommendation to find a QSO partner with
the same interest more
easily. There are also small sub segments for automatically controlled data
stations (unattended) to
separate those from the operation by individual amateurs. Automatically
controlled stations need
well known frequencies to be able to make automatic data transfer between
themselves or to be
called by interested amateurs. To avoid the risk of QRM by these
automatically operated stations
individual amateurs interested in contacts with other individuals are
encouraged to stay away from
these small sub segments. Digimodes are not limited to segments with the
indication “preferred
usage digimode�, the words “all narrow band modes � and “all modes� in the
table may be
understood literally, which is helpful during contests (e.g. RTTY) with
high activity.

Contest Preferred Segments
With its bandplan the IARU Region 1 gives recommendations to participants
and organizers of
contests to use only specific parts of the band, so called “contest
preferred segments� for contest
activities. This allows those amateurs not interested in contests, to use
parts of the bands without
contest activity. The last IARU Region 1 conference in Cavtat 2008
underlined this with additional
recommendations. Some societies (e.g. DARC, UBA, USKA, VERON etc.), but
also IOTA and the
Scandinavian Contest regulate the allowed contest frequencies by rule or
make the IARU Region 1
bandplan mandatory for participants.
Contest operation outside the specified segments is a violation of contest
rules and the adjudicator
can take appropriate measures. Though IARU Region 1 cannot force the
individual amateur to follow
the bandplan everybody is encouraged to understand the principle of self
regulation and to follow
the recommendations.

Amplitude Modulation
This mode with a bandwidth exceeding 2700 Hz is occasionally used for
historical reasons. A footnote
to the bandplan is trying to cope with such requirement: Amplitude
modulation (AM) may be used in
the telephony sub-bands provided consideration is given to adjacent channel
users. It was agreed by
the conference that a special segment for AM is not useful; it would
encourage AM which is not
intended.

Telegraphy
If CW is shown as preferred mode and usage in segments with a max.
bandwidth of 200 Hz, then they
should be used only in CW, but: CW operation is not limited to these
segments!
CW is allowed all over the bands, since in the segments for “all narrow
band modes� (up to 200 or
500 Hz) or “all modes� (up to 2700 Hz) a CW signal also fits with these
definitions. This makes mixed
operation possible, e.g. a SSB station may be called by a CW station.

Beacon Bands
Around the beacon frequencies of the International Beacon Project (IBP,
operated by NCDXF) the
bandplan shows small segments of +/- 1 kHz in which to enable propagation
studies. Unfortunately
some stations don’t always comply with this requirement, especially during
contests, and cause
interference to beacon reception.

It seems that not everybody understands that digimode usage (e.g. RTTY in a
contest) may also take
place above 14101 kHz, since the recommendation for digimode continues and
the bandwidth of a
RTTY signal does not exceed the max. allowed bandwidth of 2700 Hz. Some may
have forgotten that
an AFSK generated RTTY signal using frequencies up to 2 kHz in USB, and the
resulting signal is
transmitted about 2 kHz higher in frequency than the VFO display shows
(e.g. 14098 kHz) – which
means it is transmitting on top of the beacons!
Please avoid operating between 14099 and 14101 kHz.

What does note (1) mean?
Depending on the sideband selected a transmitted signal appears below or
above the displayed
frequency. On the bands 40m to 160m lower sideband is used for SSB. Note
(1) should remind you
that the VFO display must not be set lower than the noted frequencies. On
40m the lowest VFO
display setting for LSB in the segment for all modes with up to 2700 Hz
would be 7053 kHz. (If no
digimode activity takes place the segment of 7050-7060 kHz may be used for
SSB).

On 60m, 20m and higher bands the frequency display must be kept 3 kHz below
the upper band limit,
otherwise parts of the signal will be transmitted outside of the amateur
band. Some countries have a
limited allocation on the 160m band, e.g. only 1810–1850 kHz. Therefore
IARU tolerates phone
operation there, although this is a violation of the 160m bandplan, which
assumes a band up to 2000
kHz. In such cases the lowest possible setting of the frequency for LSB is
1813 kHz – a lower setting
will result in an out of band operation which is strictly forbidden by ITU
and national administration.
Is the IARU Region 1 bandplan only a recommendation or an obligation?

Some societies have the answer in a statement in their by-laws, requesting
to respect the IARU
Region 1 bandplan as mandatory. But also non-members should follow the
recommendations when
selecting a frequency. Adopted at an IARU Region 1 conference by delegates
of member societies, the
bandplan is based on a self-regulation process as a compromise of the
various interests of all
amateurs.

Band plans for downloading:
http://www.iaru-r1.org Spectrum & Band Plans HF
In a slightly different form of presentation:
IARU Band Plans (Region 1) - HF (in English, valid from June 1st, 2016)
2 pages, coloured [PDF]

17 June 2016
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