Richmond Amateur Telecommunications Society

Get Started with W4RAT DMR

If you're struggling to wrap your head around DMR or are just looking for the quickest way to get up and running with your new DMR radio, we're here to help.  This guide will give you an introduction to the W4RAT DMR repeater and the DMRVA network.  An end-to-end read should provide a good background for new users.  Common terms and new concepts are highlighted in bold; feel free to skim and skip around if you're looking for something in particular.  Most information is presented in general terms and can be applied to a majority of DMR radios.

There are also many great videos, how-to guides, message forums, and other resources out there.  The Amateur Radio Guide to DMR offers a more in-depth look at the topics we're talking about here and also offers some more technical insight into the workings of DMR.  The RATS Technical Committee is also happy to help RATS members needing assistance with DMR codeplug issues or other questions.

This guide will be periodically updated based on reader feedback.  If you have suggestions for this guide please let us know. 

Jump to:
DMR vs. Analog
Purchasing a Radio
Getting Programmed Quickly
DMR Programming Concepts
Operating Practices

DMR vs. Analog

Digital Mobile Radio is a standard supported by a number of major commercial radio manufacturers including Motorola, Hytera, Vertex, Kenwood, and others.  In recent years, a number of low-cost Chinese import radios of varying quality have come onto the market, lowering the cost of entry to below $150.  Connect Systems and Anytone are at the upper end of the this market, with TYT, Baofeng, Retevis, Ailunce, Radioddity, and others offering up entry-level DMR hardware at budget prices.

DMR radios convert audio to and from a digital data stream which provides good audio quality out to the fringes of the repeater.  Voice is converted to data using a codec (coder/decoder) built into the radio.  DMR uses the same AMBE+2 codec as P25, NXDN, and Yaesu System Fusion, so sound quality is similar across these three platforms.  D-STAR uses an older AMBE codec with slightly lower voice quality.

DMR uses time-division technology with two time slots, allowing for two simultaneous conversations on one frequency through a single repeater.  When two radios are transmitting at once, they rapidly alternate turns transmitting.  A radio on time slot 1 will capture a very brief slice of audio, run it through the codec to be converted to digital data, transmit that quick burst of data to the repeater, and then shut off.  At nearly that exact moment, the radio on time slot 2 will come on the air and do the same.  This process repeats many times per second.  If you listen to DMR using an FM receiver while only one time slot is active, you can distinctly hear the pulsing of the signal.

With DMR, you get two repeaters in one and superior audio quality compared to analog under marginal coverage conditions.

Conversations on DMR repeaters are organized into talk groups.  Just as some analog repeaters can be split into talk groups using multiple PL tones, DMR repeaters use numeric talk group ID's assigned to specific purposes.  Many of these talk groups propagate out across a network of interconnected repeaters allowing nearly instant local, regional, national, and even international communication at the flip of a channel switch.  DMRVA, NCPRN, AWSVirginia, DMR-MARC, and Brandmeister are examples of DMR networks, and a number of talk groups are shared across these and other networks.

Talk groups are defined as either static or dynamic.  Static talk groups are always on and do not require activation.  Usually a Local and Statewide talk group are static on separate time slots.  Dynamic talk groups are on-demand and require a push of your PTT button to activate them.  They'll remain active until cleared or until an inactivity timeout occurs.  Most dynamic talk groups on the DMRVA network have a 15-minute timeout (5 minutes for TAC channels and NCPRN).  If there are no transmissions into our repeater on a dynamic talk group within the timeout period, the talk group will disconnect.  Activity only from stations on other repeaters will not prevent timeout.  You won't hear anything on a dynamic talk group unless it's active, so if you're expecting a call on one be sure to activate it first.  You should always have a Clear Time Slot channel set up to manually disconnect these dynamic talk groups when you're finished using them.

Purchasing a Radio

RATS has some Friends of Frostfest who happen to be in the radio business.  Please take a look and consider making these suppliers your first calls for ham radio equipment and parts.

Commercial-grade gear from the major manufacturers sells new for big bucks through networks of authorized dealers.   A tiny handful of these are considered "ham friendly" and will, from time to time and on a limited basis, make equipment available to amateurs, often on a limited/no-support basis.  Sometimes ham friendly pricing is also offered, but be prepared to pay for the radio and every one of its components item-by-item off a dizzying menu of battery types, antenna types, frequency ranges, keypad styles, accessories, and feature entitlements.

When searching for new commercial gear, start with local/regional dealers.  Commercial radio dealers trade within assigned territories so the one nearest you should be your first call.  You may have more than one choice.  If you aren't certain you're working with a ham friendly dealer, just ask:  let them know you're a licensed amateur interested in purchasing a radio for non-commercial use and see if they're willing to do business.  If not, politely thank them for their time and move on.  Internet searches and message forums dedicated to DMR are good sources for leads on ham-friendly dealers.  Depending on what you're on the market for, the RATS Technical Committee probably knows some people, too.

You can save big money on commercial gear by purchasing used.  Ask around at a RATS meeting or on one of our nets, or take a look at online marketplaces such as eBay.  You'll still need to find programming software and possibly a cable, as well as a source of a fresh battery if one isn't included.  One thing to watch for is to ensure your radio is wideband FM capable.  Motorola, Kenwood, and others require an entitlement to enable these features.  An entitlement is a license key that unlocks functionality in a radio upon payment of a fee to the manufacturer, usually by way of a dealer.

Most recently-manufactured commercial gear will only operate on narrowband FM (12.5 kHz) out the box due to federal narrowbanding mandates in other radio services.  Once the manufacturer or a dealer confirms you have a valid legal reason to operate at 25 kHz bandwidth (which is permitted in the amateur service) they may choose to unlock that capability in your radio upon payment of their fee.  You can still use FM repeaters in narrowband mode, but there will be some audio quality issues at both ends of the conversation.

When deciding to buy commercial or public safety gear, consider your ability to program the radio.  Programming software for commercial radios is expensive and difficult to obtain, and you often need pricey, proprietary cables. 

Going the Chinese import route does simplify things.  A majority of these radios are manufactured and sold primarily for commercial purposes and they occasionally carry FCC Part 90 certification.  That's not important for use in the amateur service, but be aware that Part 90 radios do meet high technical standards for performance.  In any event, the import radios built for commercial service -- Tytera, Baofeng, Alinco -- do typically support both narrow and wideband FM right out of the box, selectable on a per-channel basis in the CPS.

Connect Systems manufactures and sells its own line of Chinese import radios built to high quality and performance standards with user interfaces and performance similar to Motorola hardware.  In recent months, Anytone has begun selling high quality, well engineered radios built specifically for amateur radio use.

In almost all cases, these radios will include the customary assortment of pieces and parts you'd expect to find with any amateur HT:  usually an antenna, belt clip, battery, desktop charger, and sometimes a programming cable and software, all in one box, for one low price.

Getting Programmed Quickly

In the DMR world, a codeplug is simply the file containing all of the programming data for a radio:  channels, zones, talk groups, contacts, and settings.  These are unique to each model of radio.  Many DMR repeater networks offer up a repository of pre-built codeplugs to get users up and running quickly, though these are frequently user-contributed and of variable quality.  You can find DMRVA's repository here.  To get full enjoyment out of DMR, you'll want to understand how codeplugs are set up so you can add additional repeaters and talk groups to suit your needs.

A typical pre-built codeplug will take care of around 75% of the programming work for a new radio.  Setting up a new codeplug from scratch is tedious work, so that "75%" represents a substantial amount of effort, but be prepared to spend a good bit of time updating that codeplug with new repeaters, new talk groups, simplex frequencies, and any preferred settings you would like to have.  Pre-built codeplugs almost never include analog frequencies, so you'll want to add in any FM repeaters you use as well.

As mentioned earlier, commercial and public safety grade radios from Motorola, Hytera, Vertex, and Kenwood use expensive programming software which requires substantial up-front and sometimes recurring licensing costs, if you can even get access to it in the first place.  This software is generally reserved for commercial radio dealers and repair shops though there are a handful of ham-friendly dealers that may be willing to sell it to you.  Also note that these radios are almost never front panel programmable unless you purchase an expensive entitlement to enable it.  Buy the software and cable or have a friend who's willing to update your codeplug for you.

Programming software for the import radios is almost universally free and easily downloadable.  Most of these radios come with a programming cable, else one can usually be purchased for well under $20.

Regardless of manufacturer, the programming software is usually called a CPS, or Customer Programming Software.  The look and feel of the CPS is similar across various manufacturers but there are subtle differences in programming which vary from radio to radio.

There is software which can convert codeplugs between radio models as well as import/export channels, contacts, and other details between radio models.  The author has had great success with the free Contact Manager application from N0GSG, which can import and export data between codeplugs for many radio brands.  Contact Manager can search and add contacts from DMR user ID databases individually or in bulk.  It is also useful for reordering zones and channels, which is functionality that's strangely absent from many CPS applications.

DMR Programming Concepts

DMR programming is a little bit tedious, but the good thing is it's fairly consistent from one radio to another.  If you learn one, you can pick it up pretty quick if you get a new model.  While there will be subtle differences in the exact options and features available or the way the CPS looks and feels, the procedure is generally the same across all the manufacturers.

In the world of conventional analog radios, you need to know a few pieces of information in order to be able to program an FM repeater into a memory:  frequency, offset, and often a CTCSS/PL tone or DCS/DPL code.

In the DMR world, we need frequency, offset, and Color Code.

Color Codes are numeric values between 0 and 15 which serve the same purpose as a CTCSS/PL tone in the analog world:  in the event multiple nearby DMR repeaters are operating on the same frequency, a Color Code can be used to differentiate them.  Unlike a CTCSS/PL tone, a Color Code is not optional.  While all DMRVA repeaters use Color Code 1 (CC1), this is not a standard and a repeater may use any value between 0 and 15 as assigned by their frequency coordinator.  Some newer radios built specifically for the amateur service are capable of scanning and determining a repeater's color code on the fly through front panel programming.

Unlike analog repeaters, though, those three pieces of information alone won't get you on the air.  You also need to configure your radio for talk groups, channels, and zones.  (This is where one of those pre-built codeplugs really comes in handy.)  You also need a radio ID.

DMR radio ID's are issued by RadioID.net which serves as a central issuing body for DMR and NXDN radio ID's globally.  Except in a few very specific instances, you only need one single radio ID no matter how many radios you have.  If you don't already have one, go ahead and register for one now.  Every CPS puts the radio ID field in a different place but one thing's for sure: if you leave it out, your radio won't work (or will soon be blocked by a repeater control operator).  Note that some radios (Connect Systems hardware comes to mind) will let you set a different radio ID on each channel, if you need such a thing.  Do not attempt to use a DMR repeater without a valid, registered radio ID.

Generally the best starting point in programming a radio is with the contacts.  DMR radios store two types of contacts:  group call and private call.  Group call contacts are used to store talk group ID's.  Private call contacts are used to store individual radio ID's.  You can choose to load just a few friends or use a tool like Contact Manager to download the entire database.

When creating your group call contacts, simply refer to the list of talk groups on the repeater(s) you wish to use.  Create one contact for each talk group.  The same talk group will likely exist on multiple repeaters, but you only need to create its group call contact once.  All this is establishing is the name assigned to a talk group number.  Your group call contact is telling the radio "3151 is Virginia Statewide" and your private call contact is saying "3151262 is Steve Crow."  It's just like programming a contact into your cell phone.  Your radio will match up incoming DMR calls to this contact list, so you're establishing a sort of caller ID.

One thing to watch out for:  the same talk group may have different names on different repeaters, but you still only create one group call contact.  For example, here in Richmond we call talk group 27500 "Richmond Metro" though in most other places it's simply "Local."  It's probably best to create the group call contact under the more generic "Local" name.  This doesn't affect the channel name that displays on your radio -- we'll set that in a moment when we create the channels.  Really, you can name the group call contact whatever you want.  "TG27500" would work just fine, too, but giving it a plain English name simplifies programming in later steps.

Now you want to start creating your channels.  Don't think of these in the conventional FM sense of assigning frequencies to a memory number in an HT.  We're not associating a talk group with a physical position on your radio's channel knob yet -- that won't happen until we create zones.  But we're getting close!

When you create a channel, this is where you set the frequency, offset, mode, and other parameters.  When programming an analog channel you'll also furnish the bandwidth (narrow/wide), squelch settings, and depending on your radio's fanciness you may see a number of options like signaling and personalities.  A personality is a collection of settings associated with a channel, and it's most often used to define values related to MDC1200 or other specialized signaling on an analog channel.  Starting out, you probably don't have to worry about establishing radio personalities.

When programming digital channels you create one digital channel, per talk group, per repeater.  Each digital channel needs the input and output frequencies or offset, Color Code, time slot, and one of the group call contacts you created earlier.  So you might create a contact for RX 443.5875 MHz, TX 448.5875 MHz, time slot 1, Color Code 1, referencing the group call contact "Local" you created earlier, and associate the alpha tag "RIC Metro" for display when you tune to that channel.  Repeat this process for every talk group you want to access.

To the right, we see a typical DMR channel setup in a CPS.  This example shows the Richmond Metro talk group on the W4RAT repeater.  Prior to creating the channel, a contact was added associating the "Local" name with talk group 27500.  That contact is referenced in the "TX Contact" field.

Don't forget, you'll probably also need a Clear Time Slot channel to release a dynamic talk group when you're finished talking.  Create a group call contact associated with talk group 27000 and call it "Clear Time Slot" (talk group 4000 on Brandmeister networks).  Then create a channel with all of the repeater's parameters, associated with the Clear Time Slot contact on the appropriate time slot.

As you see in the screen shot, there are a lot of parameters on an individual channel.  Take advantage of the copy/paste functions in your CPS.  Build one channel, quadruple-check it for accuracy, and use that first channel as a template to copy/paste into subsequent channels on the same repeater.  All you'll need to adjust on each additional channel is the channel name, transmit contact, and time slot.

Many CPS applications have separate programming paths for analog and digital channels.  Again, we're not assigning these to the dial yet, so the fact the analog and digital channels are programmed in different areas of the CPS doesn't matter.  Most radios will allow you to mix analog and digital channels within a zone.

When assigning a name to the channel, best practice is to use a channel name prefix to group all related channels together.  DMRVA-supplied codeplugs use a 3-letter identifier for each repeater.  This is the best way to disambiguate all of the different "Local" and "TAC 310" channels you're going to have.  Use that same identifier across all of your related channels, receive group lists, scan lists, personalities, etc.  For example, "RIC TAC 310" and "POW DCI Bridge."

Channels can also be associated with receive group lists, scan lists, and other advanced features configured elsewhere in the CPS.  A receive group list is a list of additional talk group ID's you would like to monitor on a channel, in addition to the channel's default group call contact.  These talk groups must be on the same time slot.  Some radios will let you directly reply on those talk groups without having to switch to the talk group's corresponding channel.

Many radios support scan lists which are predefined lists of additional channels to scan while receiving the selected primary channel.  You can typically adjust timing and other scan parameters, and scanned channels need not be in the same zone (or any zone -- in fact, they don't even need to be digital channels.)  You'll need to use a scan list if you want to monitor a talk group on another time slot, another repeater, or any other frequency.  Scan list priority determines which channel(s) in the list the radio should pay more attention to than others.  You might also have a look for talkback settings which determine whether and how you can reply to calls on scanned channels.

A common use of scan lists is to create a monitor all function which will allow you to hear all activity on the repeater.  To do this, you'd create one receive group list containing all of the talk groups on the repeater (both time slots), then create one channel for each time slot with transmit contact "none" linked to the receive group list you just made.  You might call them "RIC Monitor TS1" and "RIC Monitor TS2" or similar.  Place those two channels by themselves in a scan list called something like "RIC Monitor All."  From here, you can associate that Monitor All scan list with each of the channels on the repeater and manually enable the scan while you're monitoring any of the other channels.

Some radios will allow you to automatically enable scanning on a channel, in which case you might create a dedicated Monitor All channel.  Some newer radios have a digital monitor function built in which accomplishes the same thing with no programming effort required - check your manual before you do all this work.

One more new concept to know about is talkaround.  This allows you to temporarily transmit and receive entirely on a repeater's output.  Talkaround uses the receive frequency associated with a channel and otherwise honors all other channel parameters including talk group and time slot.  You should only use talkaround if you are out of range of a repeater.  An example use case would be two mobile stations within simplex range who travel out of a repeater's coverage area.  They could switch to a pre-programmed simplex channel, or they could switch to talkaround.  Often the ability to switch to talkaround is configured on a per-channel basis.

DMR simplex uses time slot 1, Color Code 1, to talk group 99.  Our local repeater coordinating body maintains lists of frequencies allocated to simplex usage by mode.  You can find these on the Southeastern Repeater Association (SERA) web site under Frequency Utilization Plans.

Once you have all of your channels programmed, you're ready to create zones.

Zones are collections of related channels.  Think of them as smaller versions of memory banks in a scanner or conventional FM transceiver.  Typically you will create one zone per repeater.  Many DMR radios use a physical channel knob which limits you to 16 channels per zone.  (Don't forget about the Clear Time Slot channel.)

It's a good idea to think ahead and figure out which talk groups are going to be most important to you if your radio constrains you to a small number of channels (16 or fewer).  One option is to create multiple zones for one repeater, with the talk groups spread across the two zones.  Or, keep it at one zone per repeater and select the most important talk groups for you.  When you build each zone, you'll have an opportunity to assign the order of the channels.  The first one will be assigned to the first position on the channel knob, the second channel in the zone goes to the second position on the knob, etc.  It's helpful (but not important) to keep your most-used talk groups in the same channel positions across zones.

Any analog frequencies also need to be placed into zones.  Even though analog and digital channels are often programmed in different areas of the CPS, most radios will let you mix analog and digital channels within a zone.  You can also create dedicated zones for your analog and/or simplex channels.  

You may choose to add your analog channels to the same zone as digital channels or create separate analog zones.  You can reuse the same channel in multiple zones, so you've got a lot of flexibility.

As you can see, there are many steps involved in codeplug creation and some planning is required.  To review:  create a group call contact for each talk group; create any receive group lists and scan lists; create your channels and link to their respective group call contacts, receive group lists, and scan lists; create zones and then assign channels to those zones.

Operating Practices

As you are now aware, DMR repeaters offer a number of static and dynamic talk groups.  Which one should you use?  In general, your QSO should take place on the smallest talk group which will get the job done.  To talk to someone across town, use Local (RVA Metro).  Further out, you might make your initial contact on one of the Virginia or US regional talk groups and then switch to a TAC channel.

TAC channels are meant for longer QSO's between users on a small number of repeaters.  The DMRVA network currently offers five TAC channels which are shared with various regional and national networks.  You can learn more about the history and usage of TAC channels here.  Rather than tie up Virginia Statewide (and thus almost every DMR repeater in the state) for a 30-minute QSO between two or three stations, switch to a TAC channel.  There's no definitive rule as to if and when to switch to a TAC channel;  just use good judgement.

Our DMR C-Bridge Repeater page has information on current talk groups and recommendations for talk group selection.

If you would like to make a call on a static talk group, operating procedures differ little from FM.  Listen a reasonable amount of time to ensure the talk group is not in use, then make your call.  It's a best practice to state which talk group you're calling on.  "AB1CDE, this is K2FGH on Richmond Metro."  To receive a call on a static talk group, no special action is required.  The talk group is already active, so when the other station calls it should come right through.

DMR radios make use of a talk permit tone.  This is an audible signal, usually a short series of beeps or "chirp" from your radio's speaker shortly after pressing the PTT button.  This is usually left off for analog channels but you want to ensure it's enabled for your digital channels.  When you press the PTT button, the radio does a brief handshake with the repeater to establish contact.  If this handshake fails, you'll get a transmit forbid tone or "bonk" from your radio.  If you hear the transmit forbid tone, check to ensure you are in range of the repeater and that the time slot is not currently in use.  On simplex or talkaround, you'll always get a talk permit unless the selected time slot is busy.

To make a call on a dynamic talk group, you first need to activate that talk group.  To do this, you simply kerchunk the repeater on that talk group.  A kerchunk a brief press of the PTT button -- just long enough to get a talk permit tone.  While kerchunking an analog repeater is a bad thing and should be avoided, it's actually our preferred way to link up a dynamic talk group.  These connections happen almost instantly and you could be landing right in the middle of a QSO already in progress on the talk group.  To avoid barging in with your call sign or other traffic, simply kerchunk, then wait a short while (30 seconds or thereabouts) to ensure the talk group is free before making your call.

To receive a call from a distant station on a dynamic talk group you will need to have that talk group active by kerchunking it first.  Otherwise you won't hear the distant party's call.

When you are finished using a dynamic talk group, use the Clear TIme Slot channel to disconnect the talk group rather than waiting for it to time out.

DMR QSO's otherwise work like conventional FM QSO's.  The same rules apply to both our analog and DMR repeaters.  In fact, the RATS Repeater Rules & Policies are virtually the same as what's expected on most repeaters.  If you haven't reviewed them lately, please take a few minutes to do so.  Our favorite repeater etiquette guide also offers some great tips and is worth a look.  Keep the subject matter family-friendly and the language clean, be courteous, share the resource, and operate according to Part 97.

Like our analog system, the RATS DMR repeater is monitored by control operators who are available to assist you should you experience difficulty with the repeater or have any operating questions or concerns.  We often monitor Richmond Metro or Virginia Statewide.  Simply call for "a W4RAT control operator."  If no answer, send a note to the Technical Committee with your inquiry.

Richmond Amateur Telecommunications Society, Inc. (RATS) is a 501(c)3 non-profit organization. PO Box 70613, Henrico VA, 23255

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