FINAL REPORT - Stakeholders - Ofcom

27.910 As 27.900
27.960 Calling and working ship to ship
27.980 Rescue organisations such as, Surf Rescue Ship to ship/ship to shore
Table 6-5 Australian Maritime 27 MHz frequencies
With the decline in use of CB frequencies and the relative low price of equipment, the
possibility of utilising this part of the spectrum for small boats should be kept in mind if
additional spectrum resources are considered necessary in the future for this category of
user. For the time being, this issue should not be pursued any further.
6.7.7 Allocation Sharing issues
NVIS propagation techniques described in section 6.5.3 may provide for the shared use
of maritime mobile bands in the range 4 – 10 MHz. These could be envisaged for
localised fixed and land mobile service operations. Whether there is a requirement for
such HF fixed and mobile services in the UK is largely irrelevant since there is a
requirement for such services in many developing countries. If their needs can be
satisfied at World Radio Conferences benefits may accrue to Europe in the satisfying of
other requirements. There is one problem already mentioned; NVIS relies on transmitting
and receiving emissions at an angle of radiation near 90 degrees. Antennas are relatively
simply such as a horizontal dipole mounted close to ground level, however such antennas
are not generally capable of being mounted on small moving vehicles, for example a half
wave dipole at 10 MHz is some 15 metres in length. On the other hand short (in terms of
wavelength) vertical whips, either loaded or tuned can be mounted on vehicles but the
angle of launch is rather low, thus the full effects of NVIS may not be realised and sharing
may prove to be more difficult. It would therefore seem that fixed services would be better
sharing partners than land mobile services.
On the assumption that antenna problems can be overcome, Maritime HF
communications are unlikely to be used at ranges less than 300 km because the MF
maritime bands will offer a more reliable service. Ship stations receiving from a coast
station located within the same general area as NVIS communication links being operated
on land will therefore be beyond the range of those NVIS links. A possibility remains that
ship stations operating close to the shore using long distance HF communications to
contact a shore station in their own country may be affected; however, ships should
normally operate to the nearest coast station for the purpose of public correspondence.
Likewise, there is also a potential interference problem if the coast station receiving
transmissions from ships lays within range of NVIS fixed/mobile operations.
6.7.8 Possible Overall Spectrum Efficiency Improvements
The introduction of modern digital systems in the HF maritime bands will increase the
overall spectrum efficiency (see Section 6.7.5). Despite the obvious decrease in the traffic
handled on HF, it seems premature to suggest the release of part of the maritime
spectrum to other services despite the heavy demand from e.g. the broadcasting service,
the fixed and land mobile services and defence systems. Additional sharing may however
be possible.
On the one hand, innovative applications and technology might make the HF bands much
more attractive than they currently are at present and as indicated below HF maritime
systems may prove to be a cost effective alternative to the current generation of maritime
mobile satellite communications.
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