Click Here for Brandmeister TalkGroups

The SERC club is pleased to announce that the DMR repeater is back on line after a lengthy absence. Due to a generous donation from a sibling of one of our members, we purchased a refurbished Motorola SLR5700 DMR repeater from a local Motorola dealer, MobileOne Communications in Venice. This is 50 watt device and we are running it at a conservative 10 watts into a 60 watt Motorola power amplifier. There is also an Advanced Receiver Research P432VDG receiver preamp on the repeater. The existing antenna is at 298+’ and is at the Laurel tower located at rt41/ rt681 intersection..

The repeater is now linked to the Brandmeister network. We have the repeater configured so that any Brandmeister talk-group can be accessed, as long as you have it programmed into your radio. Thus, they are all dynamic talk-groups as opposed to static. Had we programmed static talk-groups, you would have only been able to use those talk-groups. The original SERC DMR repeater was programmed with static talk-groups on the D-MARC network. There are over 1600 talk-groups to choose from on the Brandmeister network. The Brandmeister talk-group lists for the USA and the rest of the world can be easily downloaded from the internet. Most operators select a dozen or so favorite talk-groups and program them into their radios. Many radios have a number of zones and each zone can accept a number of programmed talk-group channels. Example some TYT radios can accept a maximum to 1000 channels, split up over a number of zones. Some radios have a fixed maximum of channels per zone, example 16. The number total channels determines how many zones you can have. If the radio can hold 1000 channels and a maximum of 16 channels per zone, then you can have 62 total zones. Other makes/ models can hold 4000 channels, and many zones.

It is almost impossible to program a DMR radio manually from the front panel keyboard. Every radio has software available to program a radio using a computer. Some software is better than others. I personally prefer RTSystems software. However, to each his own choice. I have found it very easy to use and has certain features that are a benefit when programming DMR radios. Their software costs $25.00 for an online download. They also offer programming cables for about $12.00 if one didn’t come with the radio.

Because DMR originally started out as a commercial land mobile mode developed by Motorola, the nomenclature is a bit different. I will try and take some of the mystery out of the terms.

Before you start programming a DMR radio, you need a digital radio ID number. These are obtained from RadioID.net. The number issued is unique to you and must be entered into the radio before the radio will work. Whenever you key the radio on a digital channel, that number is transmitted and displays on other radios that are on the same talk-group channel. Some makes and models of DMR radios allow for aliases to be displayed. An alias takes the RadioID.net number and decodes it and shows the callsign, name and home location of the person transmitting. If the radio is capable of displaying an alias, that contact info has to be downloaded and installed into the radio’s memory from RadioID.net. This process can be easy or it can require several steps to get the contact info into your radio. This data should be updated every few months in order to display new RadioID.net contact info as more people obtain DMR IDs. RTSystems software makes this a very simple process. If your radio can’t display aliases it will still always display the RadioID.net number.

Once you have the software of your choice installed on your computer and have a RadioID you are ready to program your radio.

You need to know some things about the DMR repeater that you plan on using. The following is for the N4SER repeater. The repeater frequency is 444.7000 MHz and the input is +5.00 MHz, the same split as analog 70 cm repeaters. DMR repeaters do not use CTCSS tones like analog repeaters. They use Color Codes. Consider them to be the digital equivalent of analog tones. The N4SER DMR repeater uses a Color Code of 1, abbreviation CC1. The DMR mode was developed to make more efficient use of the radio spectrum. Traditional analog frequencies have a bandwidth of 25 KHz. DMR takes the 25 KHz and splits it into two 12.5 KHz segments called Time Slots, TS1 and TS2. DMR repeaters can support two simultaneous conversations. DMR by design operates on the Time Difference Multiple Access or TDMA principle. The DMR repeater is listening to both Time Slots and supports two simultaneous transmissions by switching back and forth between Time Slots. This switching happens in micro seconds and a component in the repeater called a vocoder makes the switching undetectable. When you program a repeater into your radio you have to assign selected talk-groups to either TG1 or TG2. We have set our repeater up the same as the Tamiami Amatuer Radio Club in Venice. TS1 is reserved for local talk-groups and TS2 ID for all other Brandmeister talk-groups. If we stick with this TS talk-group assignment, it means that there is a reduced chance that both TS will be busy. We want to keep TS1 free as much as possible for local comms.

To summarize to this point you need have a RadioID number and know transmit and input frequency of the repeater, color Code and Time Slot usage. This brings us to talk-groups.

There are over 1600 talk-groups that relate to geographic area or use. There are world wide, counties, states, etc. There are Emcomm US, Northeast Florida ARES, Florida State ARES, American RedCross EmComm talk-groups. Others are USA, North America, states, areas of states, regions, etc. Consult the available talk-group lists and decide what you want to program. Using the software enter the talk-groups into the talk-group list in the radio.

Talk-group 9 does not connect to the internet via the Brandmeister network. It makes the repeater stand-alone, just like an unlinked analog repeater. Talk-group 2 is a regional cluster and does use the Brandmeister network. Talk-group 314598 is our SERC talk-group and it is not listed on Brandmeister. It is our N4SER RadioID number. It is connected to the internet via the Brandmeister network and can be accessed from hotspots or repeaters out of the area by whoever has it programmed in their radios. Talk-group 2, 9 and 314598 should be assigned to TS1.

Decide what other talk-groups you want to use and enter them into your radio’s list. They will be assigned to TS2. TARC has their own talk-group which is 310442 and it should also be entered into the list.

Now use the software and program a channel using what we know, repeater frequencies, color code, choose the talk-group of your choosing from the talk-group list in your radio and assign it to a TS. Remember only local talk-groups in TS1.

Once you have done this for each talk-group that you want to use and have entered your RadioID, then create a zone and put the channels into the zone . Example “N4SER DMR”. Use your software to set the time out timer and other desired options. At this point you will have created a codeplug. This is the DMR term for a program or profile.

Then send the codeplug to the radio..

When you key the radio on a TG, it links to the repeater. The repeater is programmed to unlink after 10 minutes of no input traffic. Talk-group 4000 is the universal disconnect command. You should create this talk-group channel to allow you to manually disconnect from a talk-group. It is good DMR radio etiquette to unlink when you are finished with a talk-group. This makes the repeater TS available for others to use without them having to wait 10 minutes until the repeater automatically disconnects from the talk-group.

Once you know that the codeplug works, and if your radio permits it, you can use your software to import the contact list for the alias feature from the RadioID.net website.

DMR programming can be a challenge until one understands how the different talk-groups are programmed into a radio. Hopefully, once you get the hang of it, you will enjoy using DMR.

The neighboring Tamiami Amateur Radio Club in Venice is very active on their DMR repeater. Their website www.tamiamiarc.org contains a lot of useful information including codeplugs for selected DMR radios. Check it out!

Good luck. Have fun 73’s