Working The Cluster Network.

The Basics.

The Southwest cluster is made up of a number of independent Repeaters operated by their own Repeater Groups working in tandem to create a big, if not the biggest UK network of DMR repeaters to date.

Each Repeater Group owns and operates their repeater and internet feed. Groups can join or leave the Southwest Cluster (SWC) there is no restrictions or demands on them, it is a truly independent network. The only thing we ask of you the user of the SWC is to show you’re thanks to the operators of your local repeater by joining their group and maybe make a donation to help with the running costs. Remember repeaters are not sponsored by Ofcom or the RSGB, they are totally paid for by the repeater group.

The Repeaters.

Each repeater provides the following characteristics:

• One single 12.5KHz wide RF Chanel that is divided into two 6.25KHz wide sub channels called Timeslots.
• The two Time Slots (TS) can carry separate voice QSO’s on each slots. In other words, two different and separate QSO’s on the single RF channel, at the same time.
• When Keyed the repeater transmits at 100% duty cycle. Both TS are transmitted.
  If there is only one TS that is carrying a QSO the other TS transmits idle data, which signals to your radio (known as a terminal) that although the repeater is in use, the TS that is sending idle data is free to use and will allow the terminal to transmit.
• Each repeater is capable of relaying both Voice Data, Private Call voice Data, Text Messages and supplementary data services such as D-APRS.
• The repeater sends timing information to your Radio (Terminal) so that the terminal can synchronise its transmission to that of the repeater.
• The repeater “Controls” your terminal. If your terminal is correctly configured, it will not transmit until the repeater tells it to, even if you are squeezing the life out of the PTT button.
• Once both TS become clear the repeater will shut the RF Channel down after a period of 7 seconds of inactivity.
• Just like the Analogue repeater equivalent, the DMR repeater also transmits beacons at intervals, and just like you, the repeater is required by Ofcom to transmit its callsign periodically. However, unlike you or your standard FM repeater, a DMR repeater sends both a callsign by AFSK (FM Audible) and a digital beacon. The later is processed by your terminal and is used as part of the roaming feature.
• Each repeater uses two Talkgroups (TG) one per TS. Although DMR itself can handle hundreds of TGs, (See below for description of TG’s), the SWC network keep things simple by just using the two.
• TS2/TG950 will cause your local repeater to relay your audio to all other SWC member repeaters across the Southwest.
• TS1/TG9 This Talkgroup remains local to your repeater; it is not relayed to the other SWC member repeaters. However! This TG is special. It allows a feature called Dial on Demand (DoD).
• Dial on Demand (DoD) is a special system where you can request the SWC central server to connect your communication to another repeater, or Talkgroup outside of the Southwest, indeed it could even be to a TG outside the UK (see below).
  

Talkgroups (TG).

Talk Groups (TGs) are another important ingredient in the DMR recipe of operation. Think of a TG being a meeting room, where if you set your terminal to a TG of say 1 and others set their terminals to TG of 1 then everyone is in the same ‘room’ and can hold a QSO. While your all talking on TG1 another radio operator sets their terminal to TG2 and tries to join your QSO, then their terminal will refused to transmit (This is provided the radio is set up correctly) and the operator will receive the “no service tone”. Their terminal will also ignore any received traffic that is not TG2 so effectively they cannot hear your QSO.

However when you finish your QSO on TG1 and clear the other operator on TG2 can transmit freely. Of course your now locked out of using TG1 and you then receive the no service tones when you try to transmit.

Yes I know it sounds complicated, and yes it is. BUT just remember to set your terminal to TS1/TG9 and TS2/TG950 for use on the SWC, everyone else will have to set their terminals to the same values, so you can all hold QSO’s with little or no effort.

Dial on Demand (DoD).

This feature is enabled on a repeater by repeater basis and can be disabled on request of the repeaters keeper.

Unlike the MK1 SWC which was limited to TS2/TG950 being SWC wide and TS1/TG9 being local only. The introduction of our own FreeDMR server. We can now offer Dial on Demand Talkgroups.
This is ONLY available on TS1/TG9 on your local repeater.

DoD does **NOT** require you to program hundreds of channels with different Talkgroups and Timeslots. DoD makes programming the radio terminal simple. Your terminal only requires TS1/TG9 and TS2/TG950 only!!

Two channels per repeater, that’s it!

So to use DoD change your radio channel to TS1/TG9 on your local repeater. That’s it your ready to go!
You will need to know how to get to the “Private call” option on your radio menu.

When you have finished your QSO repeat the above steps to get to the “Private call” menu. This time enter magic code of 4000 then transmit, and release. The system will report “Not connected” this means you have returned the repeater to local TG9
It is good practice to take a listen to TS1/TG9 for a few moments to check there is not a QSO taking place. As the repeater is physically on TS1/TG9 you should hear a QSO even if the repeater is connected to a DoD Talkgroup. It’s the server doing the TG changes not the local repeater.
You can transmit 5000 into the system, using the above technique and the system will report the current DoD Talkgroup its linked to, or “Not connected” which will confirm your back on the local repeater only.

Have a play, there is a lot of Talkgroups to listen or interact with!

• If you link to a DoD Talkgroup and do not transmit and just monitor, the system will automatically disconnect the DoD TG after 10 minutes.
• Also after around 15 minutes the repeater will send a spoken beacon.

Below is a list of all the Repeaters linked into the South West Cluster Network.