MORE SPACE FOR DIGIMODES ON 30m, as in the June Radcom
- GE All,
Berry M0IOW (30MDG Award Managers) emailed the 30MDG Mangers this information and thought it might be of topic interest. Some of you might have already seen this or discussed this here..if not then here it is.
Don KB9UMT 30mdg#0001
THE LAST WORD-LETTERS
THE RADIO SOCIETY OF GREAT BRITAIN MEMBERS' MAGAZINE
JUNE 2011 . RADCO
MORE SPACE FOR DIGIMODES ON 30m
JT65A is a digital mode developed by Nobel Prize
winning physicist Joe Taylor, K1JT, that allows
worldwide contacts to be made using very low
power. However it is rarely used on the 30m band
because users can't find a place to operate. Weak
signal modes need a specific 'watering hole' because
without one users wouldn't be able to find each
other; other modes stomp all over them. But previous
attempts to find a spot have resulted in conflict
with PSK users and digital networks.
The problem has arisen due to a desire to find
a frequency that is compatible with the bandplans
in Regions 1 and 3. But the truth is you can't fit any
more digital modes into 10kHz. I presume that the
existing allocation of 10kHz to digital modes was
made when 30m first became available back in
1979 when the only digital mode was RTTY. Since
then, especially in the last ten years or so, there has
been a huge increase in digital mode usage, not to
mention a proliferation of different modes. The size
of the current digital allocation does not reflect this.
In the USA, narrow band digital modes-which
JT65A is-can operate in the region 10.130-
10.140MHz. Isn't it time our Band Plan was brought
into line with this? If CW operators in the USA can
manage with 30kHz on 30m then surely so can
the rest of the world? Radio waves don't stop at
national boundaries so it's daft to have different
rules in different parts of the world anyway.
This added by RSGB HF MANAGER
Incompatible band plans are usually due to different
licensing regulations in various countries. So whilst
the IARU does try to ensure band plans are
harmonised, some inconsistencies are inevitable.
The 30m band for data modes is 10140-
10150kHz in Region 1 and 3, and 10130-
10150kHz in Region 2. At least in Region 1 we
are fortunate in that band plans are guidelines.
This is not the case in some Region 2 and 3
countries where adherence to the band plan is
a licence condition. The data modes segment on
30 metres is crowded and activity often extends
below 10140kHz in busy periods.
Weak signal modes, such as WSPRandJT65,
suffer more from unintentional interference as they
can often not be heard or seen on a waterfall. Ifs
natural their users tend to gravitate towards th
quieter parts of the band. Most JT65 activity is
between 10139.0 and 10140.5kHz.
Whilst it may be possible to achieve a
harmonised band plan across all regions, in th
meanwhile surely the best approach is to open
with tolerance and consideration for other usei
regardless of mode.
lan Greenshields, G4FSU
RSGB HF MANAGER