Monday, June 15, 2009

Repeater update

Current Status

GB3IM-R (Kionlough, Bride) has been working well for over a month now and has been an invaluable test bed for discovering the functionality of the AllStar Link software, as well as the best way to use it.

A number of local stations have made good use of the repeater, and it is covering all of the areas that it was expected to. Specifically, solid coverage is now available from the Sulby Glen Hotel, right through to Ramsey on the Lezayre road (a traditional Snaefell “black spot”). Further East, coverage is good around Ramsey and some of the Maughold area. On the coast road, coverage is good up to the Dreemskerry turn-off and, on the mountain, solid coverage is available right up to the Mountain Box.

GB3IM-S (Snaefell) has been on test for a couple of weeks and a number of iterations have taken place in coming to a suitable configuration. When it is put into service, the “personality” of GB3IM will change significantly, particularly in the following areas:

Access: 1750Hz access will disappear forever. CTCSS at 110.9Hz will be required.

Timeout: Gone.

Idents: Every 15 minutes at 00, 15, 30 and 45 minutes past the hour. The long beacon (i.e. “GB3IM Isle Of Man”) will cease to exist and the callsign will be “GB3IM H”, where the “H” indicates the CTCSS tone frequency as dictated by the RSGB.

The repeater on the mountain will be a standard, unmodified, Simoco PRF1060 commercial grade repeater with a transmitter output of 15W (The existing repeater is 5W). In common with many other commercial repeaters, there is no provision for “courtesy tones”; When the repeater is opened by a valid signal, it will relay that signal and, when the incoming signal is removed, the repeater will drop carrier immediately. This can be somewhat disconcerting for those unaccustomed to such behaviour but it is mitigated by the behaviour of the supporting system, which I will explain.

Some amateurs are familiar with the use of an “uplink” radio to access a hilltop repeater. Many EchoLink users use this technique to connect their local repeater to the internet. We are using a similar technique for Snaefell, mainly because there is presently no internet access up there. By reducing to an absolute minimum the amount of equipment on the hilltop, particularly a PC, the chances of serious problems are reduced.

The uplink radio is co-located with GB3IM-R at Bride.

When a user calls through Snaefell, the Uplink radio will receive the output from Snaefell and send it into the local AllStar network, as well as to any incoming/outgoing links to other nodes. When the user ends his transmission, the uplink radio will signal this to the controlling computer which, in turn, will briefly command the uplink radio into transmit in order to send a “Pip”. The repeater will then drop carrier, ready for the next incoming transmission either from a local user on the repeater’s input frequency or from someone accessing either from the internet or via another Isle Of Man repeater node.

It is hoped that the new radio will be installed on Saturday 20th June 2009. For a short period the repeater will be operated without the uplink, so there will be no bleeps or hangtime. From the caller’s perspective, it will appear that the repeater is not working – but it will be!

GB3IM-C (Carnane)

Watch this space. Hopefully very soon.

Other linking methods

GB3IM-R is registered with EchoLink, node 464453. Very little testing has been done on this link so far so please report any problems. This link connects to the GB3IM-S node computer at Bride and thence into the remaining IOM repeaters. Outgoing EchoLink connections are possible but, since only the Snaefell node is presently registered with EchoLink, you can only set-up an outgoing Echolink connection via Snaefell.

I am keen to hear from any local amateurs who operate, or plan to operate, simplex internet gateways – especially on 70cm.

If anyone requires clarification on any of the foregoing, please get in touch.

David Osborn


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