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In this video we'll be looking at a very useful feature in DMR called roaming. I'll be explaining what it is, how it works, and showing how you would program it. Roaming is when a radio is set to automatically move between repeaters depending on which has the strongest signal. Here we have three repeater sites, where the blue is meant to show the signal strength. In a roaming system you have to set the RSSI threshold which is the minimum signal strength that the radio will consider to be strong enough before it starts searching for a stronger signal. The RSSI threshold for each repeater is indicated by the red circles, and this is set in the radio's programming. Let's say a radio user is here, in the coverage of repeater 1.
As they move further from repeater 1 and the signal strength decreases, they'll reach a point where the signal strength drops below the RSSI threshold. At this point, the radio will start looking for other repeaters programmed into a roam list to see if they have a stronger signal at that location. The roam list is simply a list of all repeaters that the radio could use. If one of the repeaters in the roam list does have a stronger signal, then the radio will switch to using that repeater automatically. So as the user moves closer to repeater 2, the radio should switch to using repeater 2 and then as the signal strength increases above the RSSI threshold it will stop searching for other, stronger repeaters. Then if the radio starts to move towards repeater 3, the signal will fall below the RSSI threshold again and it should start searching for a stronger signal.
GW3-TRBO provides at-a-glance views of network performance from every angle: system, site, channel, slot, agency, talkgroup, and subscriber. GW3-TRBO significantly reduces the amount of time spent assembling or dissecting data from various sources while substantially increasing the amount of information readily available. Eastern Colorado Regional Network (NEW!) – Talkgroup 705. This talkgroup has been set up to allow data. We are allowing experimentation with data and texting on this talkgroup and repeaters only.The rest of the RMHAM network is strictly off limits for data and texting.
It should detect repeater 3, and move to that channel, and then once the signal is greater than the RSSI threshold, the radio should stop searching for a stronger repeater and stick with repeater 3 until the signal once again falls below the threshold. To use roaming on DMR, repeaters have to be set up to connect to each other and relay the same audio at the same time on at least one talkgroup. On Motorola systems this is called IP site connect. Note that although an IP network is required, this doesn't have to be over the internet. It can be a private IP network. Roaming works very well in commercial systems which are dedicated to only a few groups of users, but in amateur radio it's a bit more difficult. In amateur radio, many talkgroups are used and they're linked differently. Some talkgroups are linked to all other repeaters in the country, some are linked only to a certain area, and some are user activated. The area specific talkgroups can be programmed in, in a way that the radio will only roam onto repeaters that have that talkgroup, and that would work fine. The biggest issue here would be the risk that someone else will be using a repeater on another talkgroup when you want to roam onto it. This is where roaming would fail in amateur radio.
You'd have to either stop your conversation or manually set the radio to use another repeater. The second issue with roaming in amateur radio is the user activated talkgroups. User activated talkgroups become active on a specific repeater only once you have transmitted onto that talkgroup. If you activate the talkgroup on one repeater and then roam onto another repeater automatically, the talkgroup won't be active on the new repeater and you won't hear any traffic from the talkgroup until you transmit again. Commercial radio systems don't have these issues because they are usually set up in a much simpler way. They only have a small number of talkgroups (usually one for each timeslot) which means that you won't ever roam onto another repeater and find that someone else is using a different talkgroup on it already. Secondly, user activated talkgroups don't really exist outside of amateur radio. In commercial systems, the talkgroups are always connected, so you won't have the issue of roaming onto another repeater and finding that the talkgroup you were listening to is not connected.
Despite these issues, I find that it's still worth setting up roaming in amateur radio, if your radio supports it. The usage won't be as simple as a commercial system because you'll need to have all the talkgroups you're likely to encounter in a group list and have that group list assigned to every channel, so that you can hear if someone else is using the repeater already. If someone is already using a repeater you roam to, then you'd have to either manually switch the radio to another repeater, or just stop your conversation. The best way I can think of to program repeaters is like so: For national talkgroups that are always linked on all repeaters, just program all the repeaters into one roam list. For area specific talkgroups, program only the repeaters that can access that talkgroup into a roam list. For user activated talkgroups, it is probably best to either not use roaming, or to program it in the same way as you would for an area specific talkgroup but just be aware when using the radio that you'll have to activate each new repeater you roam to by transmitting on the user activated talkgroup.
I'm gonna show you how you'd program this on a MotoTRBO radio but it should be similar with radios from any manufacturer. Note that the majority of Chinese radios don't support roaming. There are different ways to program this, but I'll show you the way that I think is best. Okay so here I am in the programming software and I've set a lot of it up already. I've set a group list here and I've put all the group that I'm likely to encounter in there already. So if anyone keys up on any of these talkgroups then I'll hear it, if the group list is assigned to the channel. And I've also got all of the repeaters around here programmed in already. I'll just show you one of these so you know what to do. So you have to put in the receive frequency and the transmit frequency of course and the group list. You have to check the IP site connect box so that you can add this to a roam list. and also make sure that the colour code is correct, and the time slot.
I also recommend that you set the admit criteria to colour code free because this will stop you from transmitting on top of someone else and I recommend you set the in call criteria to 'follow admit criteria' because if you're in a call already and then someone else starts talking then this will stop you from transmitting on top of them and basically just interfering with them. So, now that the channels are all ready and set up, let's go down to here which is where you set the roam lists. So I'm going to use the default one that's here already. and I'm going to use this for talkgroup 235 so I'm going to name it 235. and 235 is the UK wide calling channel so this goes on all of the repeaters. and it transmits on timeslot 1, so we're going to put all of the timeslot 1 of these repeaters into this roam list. So there they are.
and this is also where you set the RSSI threshold which I explained at the beginning of this video. I'm gonna set it to -110 you can experiment with this a bit though and see which value works best for you. While we're here I'm also going to create another roam list. and this is gonna be for a regional talkgroup or an area specific talkgroup. and I'm gonna use talkgroup 801. Now, 801 is actually the south east of England talkgroup and I think it's actually on all of these repeaters but let's just pretend that it's only on a few of them, just for the video. So let's say it's on this one, this one, this one and it's on timeslot 2 by the way and let's say this one as well. So it's just on these repeaters here. and again let's set the RSSI threshold. Now the next thing to do is create a channel which you're going to roam from so I'm gonna create another zone here.
and I'm gonna call it 'roam'. and in this zone I'm gonna create 2 digital channels. The first one is gonna be for roaming on talkgroup 235. So I'm gonna name this channel 235. Then what I need to do is go to IP site connect check the box here and then I can select the roam list from here. 235. So it'll roam onto all of these repeaters. Now, what's important to do here is select the group list so that I can hear if any other calls come up from other people. So that I don't interfere with them. and set the contact name which I'm gonna be transmitting on which is gonna be UK 235. This is actually inherited on all of the other channels when you roam to those repeaters automatically. I'm also gonna set the transmit frequency to a frequency that I'm allowed to transmit on because the radio may transmit on this frequency sometimes. So if I set it to one of the repeater's frequencies then that won't do any harm. Also set the admit criteria here to 'colour code free' and 'follow admit criteria' and make sure that the timeslot is set correctly as well. Next let's do the second channel which is gonna be roaming on talkgroup 801.
So I'm just gonna name this channel 801. and again I have to set it to use IP site connect. Go up here, select the roam list Make sure that the repeater timeslot is set correctly Now, talkgroup 801 is on timeslot 2, not on timeslot 1, so make sure that's set. And then go down here. Again let's set a frequency I'm allowed to transmit on. Set the contact name which is gonna be talkgroup 801 And set the group list to make sure that I hear any other calls on the channel. Also make sure again that the admit criteria is set correctly. The colour code here actually doesn't really matter because this is not a real repeater here. This is not something that you're gonna be using. It will just go onto this channel initially when you select it but then it will immediately roam onto one of the repeaters which are in the roam list. So for this one when you select this channel on the radio it will see the roam list is 801 it will go and look in the roam list and it will look at these repeaters here, these channels and it will select one of these that is in range. I also recommend actually that you set the 'enhanced channel access' on all of your channels because this will stop you from accidentally transmitting at the same time as someone else.
If we have a look in here it says that it improves the reliability of transmissions by minimising collisions when 2 or more radios initiate a call simultaneously. So we now have the 2 zones in the radio: 'Roam' and 'DMR repeaters' and the user can go manually between these two if they want to roam then they can select the roaming zone and if they want to select one of the repeaters manually then they select the 'DMR repeaters' zone. One thing that you might notice is that I've actually set the contact name on all of these to 'local' which is talkgroup 9. So this is on both slot 1 and timeslot 2. Just because I've set the contact name to 'local' it doesn't mean that you can't transmit on other talkgroups because when you browse to this channel on the radio you can actually go into the contacts list in the radio and you can scroll down to one of the contacts and then just press the push to talk button and you'll be talking on whichever contact you scrolled down to. and all of the contacts that you've programmed into the radio in the contacts over here will be shown on the radio for you to use.
So I think that's all done now so you can plug in the radio and click on write and then we can go and test it out! Okay so I've just programmed in that codeplug into the radio. So let's give it a test. I'm gonna switch to the 'roam' zone. and it's now trying to find a repeater. Actually I'll switch to 801. And there we go, it has found GB7NS! Now I don't want to call on this talkgroup I just want to test it so I'm gonna go to echo test. and this is also how you would select a different talkgroup if you wanted to use any other talkgroup so you can see the whole list in here of different talkgroups that you could use. So I'm gonna go to 'echo test' and give it a test. So you can see that it works! So that's the end of the video. Don't forget to click the like button if you enjoyed it or if you didn't like the video then click the thumbs down button but if you're going to do that then please leave a comment telling me why you didn't like the video so I can improve in my future videos. And if you're new to the channel, have a look at all my other videos by clicking on my channel name which is below this video and see if there's anything else you like and maybe subscribe.
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