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Amateur Radio bandplan 're-arrangements'
for digital technologies
The transition from analogue to digital communications has been occurring
over a number of years, for example, analogue to digital cellular phones
now in its third phase, the introduction of digital television, and more
recently trials of digital audio broadcasting.
The amateur service has embraced the exciting world of digital and over
the past ten years or so, the increasing use of high frequency and pc
sound card technology has given us, PSK31, MFSK16 and the like protocols,
as well as a raft of slow scan television systems.
In recent years digital voice emissions has increasing started to take
over the commercial world of VHF and UHF communications, and it’s
not surprising that amateurs have become interested in digital voice technology
for use on
our bands.
One such development has been the Japanese Amateur Relay League’s,
(the JARL), development of an open air protocol, in association with a
number of commercial manufacturers. Digital Smart Technologies for Amateur
Radio or “D-Star” is one such development.
What does this mean for the Amateur Service in Australia? The National
Technical Advisory Committee (NTAC) was been considering how best to accommodate
narrow band digital technologies such as D-Star and has made a number
of proposals.
Firstly, in the 2 meter band, digital repeaters will be assigned to frequencies
in the 146 to 147 MHz band, using the space between existing FM repeater
channels. This is known as inter-leaving and is a common method of assignment
to increase spectrum efficiency. The are some compelling reasons to take
this approach for 2 meters, one is to remove the potentially annoying
“drone” of digital signals, and secondly, the lack of normal
FM repeater channels in some parts of Australia. It also seems to make
sense to have the uniform arrangements across all of Australia.
The arrangements for simplex operations, again to separate digital and
FM emissions, NTAC has recommended the best area for simplex D-Star activity
would be the 145 MHz segment. One suitable channel that is clear of other
use is 145.125 MHz and should be used as the national simplex digital
channel.
On 70cms, where there is less congestion, NTAC has recommended that the
first fifteen repeater channels, that is, 438.025 to 438.375 MHz, be used
for D-Star type activity.
NTAC has recommended that the arrangements for simplex activity on 70cm
be centred on a national channel of 438.900 MHz, with secondary channels
12.5 KHz either side of the national channel.
For the 23cm band, NTAC has recommend that repeater channels be assigned
in the high end of the 1293 to 1294 MHz repeater segment. And on the 23cm,
there is already a digital simplex segment between 1298 and 1300 MHz.
As
D-Star on this band uses a 128 KHz emission bandwidth, it is suggested
that channels are spaced at 200 KHz intervals, beginning at 1298.1 MHz.
NTAC will review these arrangements as D-Star digital activity develops.
Further information can be found on the WIA website and will be included
in the next edition of the WIA call book.
I would like to thank the NTAC committee, particularly John Martin and
Peter Mill for their excellent work in developing the new arrangements
for the exciting world of digital voice and data technology.
Peter Young VK3MV
Related URLs:
Icom
gives D-Star repeater to the WIA
Icom
launch new D-STAR website
Source: Wireless
Institute of Australia
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