I did a quick search for 'Roam' and 'Roaming and didn't find what I wanted to talk about, so I've started a new discussion. Mods please feel free to move this to another section of the forum if it's more approriate
When I started with DMR I was somewhat confused by the use of Roam and Roaming and this wasn't helped by TG8 TS2 being referred to as both 'Regional' and 'Roaming'. As part of my self learning, I have a better understanding of the terms and their use now. TG8 Regional (as I shall call it) is fairly easy to get your head around as essentially it used where a number of geographically close are linked on TG8 - e.g. GB7HM and GB7LP - if you call on TG8 TS2 on GB7HM then your calls will be heard on GB7HM AND GB7LP, so it's an easy way to carry out a local QSO but over a wider area than TG9 Local on just one repeater would allow. This linking of TG8 Regional is happening around the London area with many of the repeaters being linked on TG8. That's the easy bit and I'm happy with that.
By the way, please feel free to jump in an add to this discussion or correct any of my assumptions
Now on to the difficult bit - at least for me - ROAMING
Having read the various Motorola technical documents and picked the brains of other users, some of who have a significantly better understanding than I do, this is my 'take' on roaming. This is Motorola only as I only have experience on this and the CSI CS700 and I don't think that the CS700 can truly roam yet.
When setting up a digital channel in the Motorola CPS, the channel can be linked to EITHER a 'Scan List' or a 'Roam List' but not both. Scanning is easy, create a Scan List in the CPS, edit the channel to use this scan list and then edit the scan list to make sure that the channel is added as a member. Repeat for other channels as required, adding them to the scan list. Now, when you are on one of those channels and select 'Scan' on the rig, each of the channels is scanned. You can do all sorts of other clever stuff with scan, but that's not what I want to cover here.
I'd suggest that most of us make extensive use of scan, with the rig waiting for traffic on one of the channels.
So how is Roaming different to Scanning? Scanning is fine if you stay in one geographical area and are always tuned to the same repeater, but if you are travelling around you would need to manually change the rig channel and/or Zone to be on the next repeater. Of course, you could have more than one repeater in your Zone (within the 16 channel per zone limit if that applies to your rig) and scan the whole lot, but it's not very elegant!
With roaming, the rig will search all the channels in a 'Roam List' and select the one that is the strongest signal (not quite this simple, but it will do for this example). Rather than 'searching' different Talk groups on one repeater, the rig will 'roam' one talk group on a number of different repeaters and will automatically tune to the strongest repeater. So, you could set say UK Wide TG235 TS1 and happily drive around and chat to your hearts content while the rig switches between repeaters.
How do we set this up? Well, I mentioned earlier that a channel can EITHER be set to a Scan List OR a Roam List. You could just change your existing channels to a Roam list, but then you wouldn't be able to scan, so there is a better way to do this. The good news of course is that you can have as many identical channels as you wish so this is the way ahead.
I'll take a simple example. I want t be able to Roam in the North Wales area on UK Wide TG235 TS2 ant talk to the whole of the UK without manually selecting different repeaters as I travel. I've already got Zones for the repeaters I'm interested in GB7HM and GB7LP (I've actually got 5 repeaters in my roam list, but I'll keep it simple for the example) but I want to leave these as they are so that I've got the option to scan within these zones. So this is what I do:
- Create two new Zones called GB7HM Roam and GB7LP Roam
- I copy my existing UK Wide TG235 TS2 channel from my current GB7HM zone and paste it into the GB7HM Roam zone
- Same thing with UK Wide TG235 TS2 in the GB7LP zone
- Because I don't want to get confused over which channel I'm adding to the Roam list later, I rename these 2 channels to 'HM Roam UKW S2' and L'P Roam UKW S2' (It would be simpler if I didn't want to keep the scanning option with my original zones, but I'm going to need to know which channel is set to scan and which to roam)
- I create a new Roaming list in the CPS Roam folder (down at the bottom of the list) called 'N Wales UKW S2'
- I now add the two new channels 'HM Roam UKW S2 'and L'P Roam UKW S2' as members to the 'N Wales UKW S2' roam list
- Phew, nearly there
- I go back to the 2 new channels 'HM Roam UKW S2' and L'P Roam UKW S2' and I need to edit them as they are still set to a scan list and not the new roam list
- Using the Scan/Roam List drop-down box in the channel edit window, I set both channels to the roam list we have just created - look for 'Roam UKW S2' Fortunately, the CPS tells us if it's a scan list or a roam list
Right, we should be good to go now
Write the code plug to the rig (you did save you existing code plug in case we've hame a total Horlicks of this?)
After the rig has rebooted/restarted, select one of the new zones 'GB7HM Roam or 'GB7LP Roam' - in our example, there's only going to be one channel in each 'HM Roam UKW S2' and 'LP Roam UKW S2'.
I select the nearest repeater so it's zone 'GB7HM Roam' and channel 'HM Roam UKW S2'.
The yellow LED on the rig will now start to flash and there is a new 'magic wand' type antenna symbol on the display. What the radio is doing is looking for the strongest repeater listed in the roam list we created. Once the repeater is found, the LED stops flashing and now you can roam between the 2 repeaters without changing the channel on the rig as this will happen automatically.
Right, now for the acid test. Select the other repeater zone, one that you know is out of range - in my case GB7LP Roam and LP Roam UKW S2 - and watch what happens. The display shows LP Roam UKW S2 and the yellow LED is flashing as the rig searches the Roam list. When the LED stops flashing, the rig has magically retuned to the channel HM Roam UKW S2 - hooray, it works
I've only used 2 repeaters in my example, but I have 5 in all, each with 4 talk groups (obviously TG9 Local isn't going to work with roaming as it's only local to that repeater and the signal isn't linked to any other repeater.) It does get a bit more complicated as you add other zones and channels and eventually other Roam lists.
This is the point were all my credibility disappears, as although this SHOULD all work when I hit the road, I will admit that I haven't actually tested it whilst driving around
Things I don't yet fully understand and I'm happy to be enlightened here:
- Each repeater should 'beacon' i.e. send out a data message periodically so that the roaming radio can find it if there isn't a conversation going on at the time. I understand that not all repeaters are doing this and if they all were, would the timing of the beacon transmissions would have to be deconflicted?
- Although it wouldn't really be practical, could you put ALL repeaters into the Roam list (16 max?) and happily roam the whole UK? Geograhical areas seems to make more sense
- Do the repeater owners have to get together to co-ordinate this whole roaming thing or will it just work?
OK, if you have got to the bottom of this post, I'm sure you have questions, corrections (there must be some typo's in that lot) or will tell me that I'm just plain wrong - fill your boots