Introduction to Linking Proposal
Posted By GM1WKR On 3rd November 2009
About the Linking Proposal
As you may be aware the repeater group have submitted a proposal to Ofcom and the ETCC (Emerging Technologies Coordination Committee) to link GB3GN and GB3NG. Linking has been a long term ambition of the Group. The full text is available on our website but it has been written for the gurus at ETCC. This update aims to answer some question that members may have. Our proposal will hopefully be considered late November during the next ETCC meeting. The process of gaining permission may take several months.
The linking proposal texts can be viewed at here.
Proposal in a Nutshell
We have proposed to permanently link GB3GN and GB3NG using a method called “In-Band Linking”. This is where one repeater listens to the others output and then relays. Control logic and control tones take care of establishing the link. Essentially, this would look like one repeater so we have asked to operate it under a single callsign, GB3GN. We have also asked for the ETCC’s opinions on expanding the link to GB3SS and possibly a third site near Huntly. This will guide talks with Moray Firth ARS (MFARS) so we can plan how we could achieve that link in the future.
Advantages
There are many advantages of having a wide area repeater system in an area like Grampian. The most obvious advantage is coverage. The link would bridge the gap between the northern and southern areas of Grampian.
It would be possible to hold a QSO between basic mobile stations, one in Montrose and the other in Fraserburgh some 80 Miles away. Base stations as far apart as Angus and the Moray Firth will be able to communicate which could be handy for weak-signal data mode talk-back, propagation tests and will make nets more possible and interesting. If GB3SS is included coverage will be very impressive indeed!
Other less obvious advantages include bringing the Amateur community together by having a single region wide calling channel. Novice stations and those unable to erect large antennae will have better access to the wider community.General calls go mostly unanswered on the repeaters, we believe you will be more likely to get a reply if you can be heard further afield!
The Group will encourage use of the network for News broadcasts (GB2RS), inter-club QSO, training nets, RAYNET use and other community activities. We need to justify our repeaters to Ofcom so we need to ensure they are used.
Grampian lacks a regional calling channel and a centre of regional activity. In most areas a simplex channel would be used for calling and working. Due to the mountainous terrain and large distances between stations this is not always possible in the North East.
Disadvantages
Given the very low traffic levels on the existing repeaters it is very difficult to think of any disadvantage to linking. However, some may be concerned that the repeater will become too busy – this is unlikely given the current usage and population in Grampian.
We hope that the link will increase traffic levels to the point where we have a vibrant and usable system. If traffic levels increase beyond reason then the group will look again at isolated UHF repeaters or, possibly, an overlay network.
Operators will need to use good radio procedure, be willing to allow other stations to make calls during ‘rag chews’ and keep the repeater free for News broadcasts etc. The repeaters are a shared resource but we are confident that the good nature and friendly disposition of local Amateurs will prevail.
Why a Static Link?
The RG has a remit to provide communications for Grampian Region so we are not looking to compete with dynamic linking systems such as IRLP or D-Star. These excellent systems allow operators to link via the Internet to nearly anywhere in the world.
Our aim is to provide solid Grampian Wide communications that are accessible with the simplest of equipment to as many people as possible.
Operating
Repeaters are frequently used by mobile stations and must, therefore, be easy to operate and not distract the driver. So our proposed system will be simple to operate, indeed, you will not notice many changes except for coverage.
If you live south of Aberdeen then you will probably use the GN frequencies to enter the network, those in the north will use NG as an entry point. Those who can hear both repeaters would choose the one with the best signal.
Either way, if you are heard on one repeater then you will be relayed to the other with no further effort on your part.As a user, you will not need to issue special CTCSS or DTMF tones to use the link. This is known as “Access One, Access All”. Simples!
The Future
MFARS are very keen to include GB3SS in the link. Both groups are talking to determine the best way to achieve this. At this early stage it is difficult to say what is possible and whether an intermediate site (near Huntly) would be required for linking. It is uncertain at this time if a link to SS would be dynamic (user initiated) or static (permanent).
There is also a possibility to add UHF gateways to difficult areas (such as Aberdeen City and Deeside). These would serve a small geographical area that lacks coverage and lift signals onto the main network.
All of this will take time to achieve but we are on our way. In the meantime we await a response from the ETCC. Fingers crossed!
