MotoTrbo Newbie Questions

[W8UU]

Old school radio guy here. If you're wanting to set up a new base-and-mobile simplex or repeater system, what else is involved in a MotoTrbo installation beyond having the frequency or frequency pair approved by the coordinator. I'm reading about things like slots, color codes, talk groups, TDMA vs. digital. Can someone educate me on what this is and how you choose something for a new system. Are you required to use Motorola radios or will any digital-capable radio work on MotoTrbo? If this is the wrong forum group, I apologize, but all of this seems to be exclusive to Motorola MotoTrbo radio systems.

 

[dickie757]

Do you use DMR? If not, pick up the tried and true amateur workhorse...the Anytone D878uv. It is usually listed on qrz by folks that cant figure it out, and the return window is long gone.

After that, look around your area for some DMR repeaters that are on the air. If you find any, the group or individual may have a website explaining its use.

Get comfortable with the basics, then slide over to /\/\ side.

The basics:
Get a radioid.net ID
Get a radio
Get the info for repeater
Put the info into VFO of radio
PTT

There are a million resources on the web to learn how DMR works. When you get good at it, quit your job and get hired on at a radio shop pushing a broom in the install bay. Next thing you know, you'll be at Schaumburg going through Applied Networking class.

Good luck,
Dickie

 

[alcahuete]

If you don't know the absolute basics about DMR, you probably shouldn't be trying to set up a DMR repeater. Go out and do all the learning you can. Watch Youtube videos (there are TONS), etc. Slots, color codes, talkgroups apply to all DMR radios and systems. Has nothing to do with Mototrbo.

 

[W8UU]

If you don't know the absolute basics about DMR, you probably shouldn't be trying to set up a DMR repeater. Go out and do all the learning you can. Watch Youtube videos (there are TONS), etc. Slots, color codes, talkgroups apply to all DMR radios and systems. Has nothing to do with Mototrbo.

I don't have plans to set up anything, I'd just like a basic understanding of what other factors are involved besides the operating frequency. I'm from the analog days of transmit, receive, and PL/DPL.

 

[W8UU]

I'll ask elsewhere. Sorry to bother you.

 

[dickie757]

Man, its not like that. Dont ask, go get it.

Based on your username, it seems like you have an AE license, amiwrong? That means you have half a brain.

DMR--that is the industry name.

MotoTRBO--that is Motorola's trademark name.

Facial tissue vs Kleenex

Colorcode is just a number. It has to match to get the repeater or radio to pay attention.

Timeslot is a duration of time. Timeslot 1 then timeslot 2 then ts1 then ts2 then ts1 then ts2 until your timer kicks in.

Most repeaters, and some simplex radios use two slots. The duration is really short, 30 milliseconds, with some included overhead. TS1 will have all of the info necessary to open up the repeater or radio and ignore ts2 and all that is happening there. Your radio does this by literally stopping its transmission for the 30 milliseconds that ts2 needs. Then it kicks back in for its turn.

Talkgroup is the number that folks gather 'round. It can be an individual user, in that case, it's called a contact ID. If it is directed to a repeater, then it can be considered a TG. People set up their radios and repeaters to listen to specific talkgroups, or a short list of TGs. Too many will wear out your antenna.

And of course there is frequency in MHz.

A bunch of work goes into the networks that these radios and repeaters will talk to. That is the area I am learning, so...I cant help there.

That should be enough to peek your curiosity.

 

[alcahuete]

I'll ask elsewhere. Sorry to bother you.

More than happy to help, but explaining DMR in its entirety isn't something that happens in a forum post. I wouldn't have any fingers left. Use the resources at your disposal. Youtube videos are great for figuring it out, programming the radios, etc. If there are any specifics, ask away.

 

[CanesFan95]

1 DMR RF frequency has 2 timeslots allowing 2 different conversations to occur simultaneously without interfering with each other. Digital comms rather than analog do not need to transmit full-duty cycle to transmit compressed audio if they're Time Division Multiple Access (TDMA). The 1st conversation uses timeslot 1 and the 2nd conversation uses timeslot 2. They rapidly alternate on/off on/off so they don't interfere.

To differentiate different channels on a radio, an arbitrary number value called a talk group ID is assigned to each channel knob position on the radio. The color code is the DMR version of analog CTCSS. For 2 users to talk to each other, both radios must:

• be on the same RF frequency with the same repeater offset.
• have the same color code.
• have the same TGID.
• be on the same slot.

DMR can be trunked or conventional. Capacity Plus / Capacity Max are Motorola's proprietary trunking formats. Conventional is not proprietary.

 

[W8UU]

Thank you. You answered every question I had, especially on the terminology.

I appreciate it.

 

[kayn1n32008]

I'll ask elsewhere. Sorry to bother you.

DMR uses Time Division Multiple Access(TDMA), to share a single 12.5kHz radio channel(pair if using a repeater). In the case of DMR a single RF channel can have 2 unique, simultaneous, voice paths.

Color Code:

Works similar to PL or DPL. It is a channel access method. If the transmitted color-coded is different than what the repeater is programmed with, it won't respond.

Time Slots:

DMR has 2 time slots. Time Slot 1(TS1) and Time Slot 2(TS2). These are the 2 audio paths.

When 2 separate users are transmitting, one programmed for TS1 and the other for TS2, each radio is keying and unkeying very rapidly, approximately every 30ms. The radio programmed for TS1, the first 30ms, then it unless for 30ms, while it is unkeyed, the radio programmed for TS2 keys up for 30ms. During each 30ms cycle each radio transmits enough data to bridge the 30ms its not transmitting. To each user, there is no interruption in audio on to the radios receiving.

The repeater provides the timing reference to define TS1 and TS2 to the user radios.

If the repeater is in standby(not transmitting), when a radio keys up, it sends a series of 'wake up' packets. This is so the repeater can key up, establish time slot sync, and tell the radio when to start transmitting on the slit it is requesting. The repeater transmits a continuous carrier, regardless if it's one or two timeslots in use. Only the user radios rapidly key and unkey.

TalkGroup or GroupCall:

Think of these like virtual channels. This allows mtiple users to utilize the repeater, with out having to hear the other users. For conventional repeater use a Talkgroup can be any number from 1 to 16777215.

The exception for this is Motorola Capacity Plus trunking, Talk Group numbers are limited to 1-254. 255 is reserved for All Call


Contacts:

Every DMR radio needs a unique numerical ID, a Radio ID(RID). It can be any number from 1 to 16776415. The contact list allows you to alias the RID with a name.


The exception for this is in Motorola Capacity Plus trunking, RID can only be 1 to 65535.

Ham radio uses conventional DMR. Repeaters are linked via the internet to form huge networks. Some can also use 'hot spots'.

Hams need to be assigned an RID through radioid.net This is held in a database that can be down loaded and dumped into many DMR radios, so you don't have to build your own contact list.