Tell me about RX Group Lists.

[newsphotog]

I'm working on programming up some Motorola radios for DMR and I'm confused by the RX Group Lists function. What is it? Do I need to use it? Some articles I'm reading makes it sound necessary while others do not. Can someone explain this setting to me in layman terms?

 

[N4KVE]

Not needed at all. It scans TG's, but receive only. Just use the regular scan list. I own 8 DMR radios, & the rx list is blank on all of them. I still don't understand why they exist, but are useless to me.

 

[KE5MC]

I recently read a document that helped me understand how to use it. So this is my take on it after using both Scan Lists and RX List.

Mostly I see it as operational convenience. This may play out differently for commercial use vs. ham which I use from the ham perspective.

On a repeater I will have two RX Lists, one for slot 1 and the other slot 2. All TGs for slot1 are in the slot1 RX List, same for slot 2. If I'm on a slot 1 talk group I will hear any activity on any other TG in that time slot. Same if I'm on a slot 2 channel I will hear other slot 2 activity. I know there are lockout to keep you from transmitting on a slot if busy, but you don't hear the activity. Once setup you don't have to do anything from the front panel. I have never tried looking at RX List working across repeaters and have only started using RX List in the few weeks.

Scan List I have used across repeaters or more accurately zones. Once setup you have more flexibility as you can setup different Scan Lists and pick out different channels you want to make sure you don't miss.

From the operational standpoint RX List once setup are always functional and working. Scan List beyond the setup require you to pick a list and then enable scanning. So I think you can see where I'm coming from on the operation convenience aspect.

Others will surly have a different point of view.

Mike

 

[Project25_MASTR]

RX Lists just monitor the defined talk groups on the time slot. I usually put the talk group of interest in it's own RX List but the idea of having it is so someone like a supervisor could monitor a supervisor channel and employee channel on the same time slot without having to configure a scan list (saves battery compared to scanning).

 

[N4KVE]

Buy many people hear a conversation on a RX list, & try to answer it. They then wonder why nobody is replying to their attempt to transmit.

 

[N1GTL]

If you are using a roam list, you cannot scan. The RX Group List is your only option to monitor more talk groups than the one you're on. I have found them to come in handy on some Capacity Plus systems.

I had a customer that wanted the MAN DOWN feature on all radios and, if any MAN DOWN alert occurred, they wanted every radio to receive it, no matter what talk group they were on. This was on a 2 repeater, single site capacity plus system. They have 5 talk groups. A MAN DOWN alert can't be assigned to ALL CALL. I created a sixth talk group called MAN DOWN. The radios were programmed to be able to access 5 talk groups with the channel selector knob. In the RX Group List, I put the MAN DOWN talk group and I made that talk group the emergency revert. No one could go to the MAN DOWN talk group but every radio was always receiving it. This was the best solution I could come up with and it would not have been possible without the RX Group List.

 

[Firebuff880]

If you are using a roam list, you cannot scan. The RX Group List is your only option to monitor more talk groups than the one you're on. I have found them to come in handy on some Capacity Plus systems.

I had a customer that wanted the MAN DOWN feature on all radios and, if any MAN DOWN alert occurred, they wanted every radio to receive it, no matter what talk group they were on. This was on a 2 repeater, single site capacity plus system. They have 5 talk groups. A MAN DOWN alert can't be assigned to ALL CALL. I created a sixth talk group called MAN DOWN. The radios were programmed to be able to access 5 talk groups with the channel selector knob. In the RX Group List, I put the MAN DOWN talk group and I made that talk group the emergency revert. No one could go to the MAN DOWN talk group but every radio was always receiving it. This was the best solution I could come up with and it would not have been possible without the RX Group List.

We do something similar for text messages such as NWS alerts an property wide notices. Even now have a university where the Rave mass notification system inludes groups on the multi-site capacity plus system through our solurion. .

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[KG4INW]

From the current System Planner (with regards to Scan considerations, emphasis is mine):

A Group Scan is an optimized way to scan for multiple groups on the same channel (slot). The radio monitors the channel from either the repeater or directly from another radio to determine which group is currently transmitting. If the group transmitting is one specified in the Group Scan List, the radio will stop and listen. The radio is allowed to talkback to the group for the duration of the call hang time. This call hang time overrides the TX Contact Name setting of the channel. Because only one call takes place on a channel (slot) at any given time, the scanning radio will not miss a transmission of interest, regardless of the length of the group list. A Group Scan is configured by creating a group list and adding groups already in the Contacts folder. This group list can then be selected as the RX Group List of a particular Channel. The Group Scan does not have the advanced features and configuration options of a channel scan. For example, once configured via CPS, the Group Scan cannot be turned on or off and members cannot be added or removed. Furthermore, the configurable scan options (Scan Hang time Timer, Talkback, and others) do not control the Group Scan. The Group Scan should be used in simple systems where no advanced scan options are required. If advanced scan options and features are required, a Channel Scan should be configured instead.

Later on, it also states:

The group list controls which groups a radio will hear when tuned to a selected channel. For example, if members of the Maintenance group should also be able to listen to other groups on the channel, those other groups would be added to the RX Group List; if members of the Maintenance group should only hear traffic related to their own group, then only the Maintenance group would be added to the group list.

The System Planner contains everything one would need to know about TRBO systems but is over 500 pages!