Thanks to Mike Meyers K3DO for an interesting perspective and please follow his blog
If you are an amateur radio operator and have not been living under a rock, then I am sure you have heard of one of the digital modes: D-Star, DMR or Fusion. You may be wanting to dip your toes into the digital modes water but not sure which pool to dip them in. This blog post is intended to present a fair unbiased opinion on each of the modes.
Not until the end will you learn my preferred mode. I use all of the modes I will discuss. There are additional digital modes like P25, and Nexedge that I have not used and are also much less prevalent that I will not discuss. I do not have enough knowledge of those modes to represent them.
Also, I want to make sure up front that this is not intended to bash any one mode. I like all forms of technology and really do not like the people that are so biased toward one that every other mode is bad. Each of these modes has a place and my goal is to help you decide which one fits you the best.
I am going to start off with a quick synopsis of each of the modes we are going to discuss then we will get into the comparison.
Of the 3 modes we are going to discuss, D-Star is the oldest. It was created by the Japan Amateur Radio League (JARL) and is an open standard. It is important to note that is was created for Amateur Radio. Most people relate Icom with D-star as they have been the primary manufacturer of D-Star equipment, however, they are just a manufacturer that has implemented this open standard into their products. There are other manufactures that make add-on boards for D-star. There is also a lot of other solutions for getting on D-Star that do not require a radio or local repeater. We will discuss these later.
Digital Mobile Radio is known as DMR and sometimes you will hear it referred to as MOTOTRBO. MOTOTRBO is the motorola implementation of the DMR protocol. DMR originated as a business communication standard in Europe. It is important to note that it was created for commercial communications, this will help to explain some of it’s features. There are many manufactures of radios for DMR and they vary greatly in price.
Mostly referred to as Fusion is the newest digital radio mode. It was designed by Yeasu and is not an open standard. Yeasu is the only manufacturer of radios for this mode. Yeasu repeaters are true multi-mode capable and can replace an existing analog repeater while still providing digital capabilities. It can also transcode an incoming digital signal to analog or an incoming analog to digital or it can transmit what it receives, no matter if it is digital or analog.
Yeasu offered a special price to radio clubs and groups. You could get the repeater for $500. Clubs with old repeaters and looking toward digital saw that as a great time to update their repeaters. Because of that there are lots of System Fusion repeaters around. But most of them still only have FM analog users on them.
The following is a comparison chart of features of each mode then after the chart I discuss each feature listed and go into more detail on each mode.
|Feature / Item||D-Star||DMR||Fusion|
|Ease Of Use||Easy||Easy||Easy|
|Ease Of Programming||Medium||Low||High|
|Access The Network via “Non Radio”||Yes||No||No|
|Multi-band Radios Available||Yes||No||Yes|
|Can Send Data||Yes||No||Yes|
|Bandwidth||6.25||12.5||12.5 / 6.25|
|Concurrent Voice Channels||1||2||1|
|Mixed Mode Repeaters||No||With Limitations||Yes|
|Ease of Multi-User||Good||Poor||Good|
Now lets go through each of the features and talk about each of the modes and why I rated them the way I did.
Ease Of Use
All of these modes are easy to use. They are different than analog so it takes some getting used to but none of them are difficult to use. If I had to pick the one that is easiest to use, it would be DMR. As we will discuss in more detail below, DMR is not as flexible and therefore, it is easier to use and more structured.
Ease Of Programming
It is a bit of a mixed bag in this category. D-star is not hard to program, however, there is a new concept that you have to understand first and that is routing. With D-star you can talk to your local repeater, another repeater, a reflector which can have 10 or hundreds of repeaters connected to it or even an individual person. This sound complex and complicated but one you understand that your gateway is attached to the repeater you are talking to, it is very simple.
I put DMR into the low category because depending on the radio you have depends on how difficult it is to program. The concepts initially sound simple but it is complex to implement. You have to know what each repeater is carrying as far as talk groups and on which timeslot, etc. The other thing is, some of the commercial radios that do DMR like motorola require some very expensive software to program them ($300 for 3 years) unless you have a friend that has it and is willing to program it for you.
For Fusion, programming is not much more difficult than an analog repeater, because by itself System Fusion has no connect-ability and it is nothing more than a repeater. If your repeater has Wires-X installed it is a little more complicated but for just the radio portion, it is just as simple as analog.
Again, this is a bit of a mixed bag and even within each mode. For D-star, the primary manufacturer has been Icom, there are other manufactures of add on boards for other radios. The Icom gear I would say is in the medium to high range. However, for around $100 you can get a USB based device that you plug into your computer and you are on the D-Star network and can talk with your computer to any repeater, reflector, etc.
There are 2 companies that say they are coming out with D-Star radios soon, if that happens the pricing in this market could change. An entry level handheld for D-star is around $300.
The cost of DMR radios vary greatly, there are many manufactures of radios for DMR. You can get a Tytera radio in the low $100s or go up to a Motorola radio that is above $500 approaching $1000.
With Yeasu being the only manufacturer of radios for System Fusion, you are limited. The entry level handheld radio for System Fusion is in the mid $300’s
This is a category where I may get some flack, I rated both D-star and System Fusion high and DMR Low. I will explain my reasoning behind this. On D-star, if I want to listen to a specific reflector or connect to a repeater anywhere in the world I can do that through my local repeater, my hotspot (more on this later), devices connected to my computer, etc. If I am using my local repeater, I do not have to have the repeater owner do anything.
System Fusion works similarly if there is a Wires-X node attached to the repeater. There is nothing required of the repeater operator and you can go anywhere at any time.
DMR has no flexibility. The repeater operator decides what talk groups he wants to allow, which ones are pinned up (always on) and on what timeslot. He tells the C-bridge operator what he wants and that is what you get. If you have a friend that is on a different talk group, to bad, so sad you cannot go to it. What is available is fixed and not flexible at all.
You have to remember that DMR was created for commercial use where they do not want the flexibility. They want the user to not have to think about anything, pick your channel and use it. Unfortunately this does not match the experimentation part of amateur radio.
When I talk survivability I am referring to in the event network issues or natural disaster occur. Each mode works very differently and each have it’s pro’s and cons.
Just to note, every mode can survive on it’s own as a local repeater.
D-star uses regular internet DNS to connect it’s nodes. If one node goes down, it does not affect your ability to connect to another one. Of the 3 Modes, this is the most survivable mode, there is no reliance on a central control system.
DMR requires it be connected to a C-bridge. I think some explanation is required here. Unlike the Fusion and D-Star repeaters, DMR requires a central controller called a C-bridge to function. Think of it like the dumb terminals of old mainframes that displayed the data and took input but sent it all back to the main computer to process.
The problem is if the C-bridge becomes unavailable the repeater can only work locally, it can’t go around the C-bridge to other repeaters that are still working. So as an example, if your repeater is connected to a C-bridge in Boston along with 100 other repeaters up and down the east cost, if something happens, natural disaster, terror action or someone accidentally cuts the cable to the data center, 100 of the east coast DMR repeaters just went offline as a network until that is fixed.
Because of the dependency on the central control, I rated this as a low.
I rated System Fusion as a low also, I know I just said it has more logic, what gives right? Well, I recently was told that the central control for Wires-X is in Tokyo Japan. This is nothing against Tokyo Japan, but there is a lot of things that can happen to the internet between the US and Japan. Also, what does that do for latency? So in addition to be a central controlled system, it is very far away and just asking for trouble.
So I need to explain what I mean by extendability. What I mean by extendability is anything beyond a radio to repeater. What other options are there to extend access to the network.
For all 3 modes, there is a device called a DV4Mini (US Seller, German Seller) that allows you to access the network for D-Star, DMR and System Fusion plus a couple of others. To use this you must have a radio that can operate in the UHF range for the mode you want to use. So you must have a D-star, Fusion or DMR radio in addition to the DV4Mini. So why rate DMR and Fusion low?
The DMR currently available on the DV4Mini is tied to the Hytera DMR network and most repeaters are tied in the DMR-Marc network. There is only one talk group that connects between the 2, 4639 Nationwide. So, you can talk anywhere on the Hytera network but that is not the most common network in use. With Fusion, yeah you can talk digital but no Wires-X. Also, in both modes, you cannot easily change talk groups or rooms from RF, you have to change it in the software.
Now with D-star, there are tons of different ways to get on the network and it seems like there are new ones coming out every week. The DV4Mini will work but you can also get DVAP‘s, DVMega boards that you connect to a Raspberry pi and have your own mini hotspot, there are USB dongles like the Star*DV that plug in via USB and you can connect up a Icom Microphone and use it just like a radio over the internet from anywhere.
If you want to do more of the computer thing with a headset there are a number of USB dongles like the ThumbDV, DVDongle, and there are many many more. If you wanted to create your own repeater or high powered hotspot, free software on a raspberry pie and a low cost GMSK modem and one or two radios that have the din data plug in the back you are up and working. I have a 20 watt hotspot that I can reach for miles around, a battery powered portable hotspot I plug into my lighter in my car to charge. Using a wireless hotspot from my cell carrier, I have d-star anywhere I go as long as there is cell service or a repeater.
If you are an experimenter, then of the 3 modes, D-Star is the way to go.
Of all of the modes, DMR has the most manufactures of radios at current. Because of the large number of manufacturers you have a wide range of prices as well. The low end Chinese radios come in in the mid $100 range but the high end and very reliable ones like Motorola still up close to the $1000 Range if purchased new.
Icom is by far the main manufacturer for D-Star, if it was not for them it would be more like D-what? Other manufacturers have cards you can install to make them D-star capable but none are nearly as popular as the Icom radios. There has been rumor of 2 other companies entering the D-Star market this year.
As mentioned before Yeasu is the only manufacturer for System Fusion.
Access The Network via “Non Radio”
This goes along with the extendability above. At current D-Star is the only mode that has the ability to connect to it without a radio involved.
Multi-Band Radios Available
This category is an oddity to me and I am sure at some point this is will change. Both D-star and System Fusion have radios that work on both VHF and UHF. However, DMR does not. So if you live in an area where you have both VHF and UHF repeaters you need to buy 2 different radios if you want to work both bands.
Why is this? I do not have an official answer but it would make sense if the radio is for business use, your repeater is only going to be on one band so why pay for a radio that can support more than one band? This can become a challenge depending on where you live. However, more than 90% of DMR repeaters are UHF. But there are still some VHF repeaters out there. Some organizations have good reason to stick with VHF, but it is not the norm. So if you live in one of those areas where you have both, you will need to buy 2 radios and label one VHF and one UHF.
The D-Star and Fusion radios are all field programmable. For DMR it is a bit of a tossup. Some of the new DMR radios allow you to program them from they keyboard, the ones that do come by default not allowing you to program them, you have to use the PC programming software to turn on that feature.
Other DMR radios do not have the option to field program them at all. So why is this…. It goes back to it being designed for commercial business use. You would not want your bus driver being able to change the programming in the radio. You want to control how the radio is configured so everything is standard, etc.
All of the modes have the ability to connect to anywhere in the world if they are attached to the internet. Each mode does it differently but there is a big difference between D-Star and Fusion compared to DMR. It is like a push pull model. In D-Star and Fusion, you tell the repeater or other device you are connected to what you want to connect to and it goes and does that. Both of these modes can connect to anywhere and anything. You find a new repeater was put in timbuctu and you can connect to it.
In DMR, it is pushed to you, you cannot do a link request, you can listed to what talk groups are setup for your repeater. To get a new talk group added you have to talk with the repeater operator and get him to ask the C-Bridge owner to add a new talk group, assuming the repeater operator wants to do that.
In this category, DMR and Fusion have excellent voice quality. It is noticeable especially when you go from analog to either of these modes. D-Star has good audio, much better than analog, but sounds a bit mechanical.
D-Star and Fusion both send your callsign in digital format every time you key up the Mic. According to the FCC this qualifies as an ID. So technically you do not have to voice ID on either D-Star or System Fusion. However, it is still good to keep in practice for when you are back on analog.
DMR sends a radio id and your subscriber ID (CCS7 ID) in data, not your Callsign. This does not meet the FCC ID requirement so you must still voice ID when using DMR.
On D-Star and Fusion, when you hear a contact, there is a header that your radio receives that has details about the user that is connecting. From that you can see the name of the person, their call sign, a short message and if they have GPS enabled, you can even see direction and distance information.
With DMR, their subscriber ID is what you get, to see who is calling you would have to enter into your contacts everyone you know, otherwise there is no user information available.
There are radios available for all modes that can provide GPS data. However, since DMR does not meet the ID requirement that are required, it is illegal to send the GPS data when using the radio under Part 97 Rules.
In both D-Star and System Fusion, the GPS data is used to display the direction and distance between 2 contacts. In addition, in D-star you can click on the orange link in the dashboard and view it on a map. Also, the GPS data in D-star that they call DPRS is transmitted to APRS. So if your D-star radio has GPS and is enabled, you can look on sites like aprs.fi to see your location reported.
Can Send Data
All of the modes have some form of data available. In D-star you can send up to 9600 Kbs data. It is just data not formatted messages, etc. In DMR you can send text messages. In fusion you can send formatted messages, pictures, etc.
It would seem more thought was put into System Fusion as far as using the data features without connecting it to a computer to generate formatted data.
Each mode uses the bandwidth differently. However they are all narrow band compliant. Not yet a requirement under Part 97 Rules but it could become a possibility. D-Star uses 6.25 Khz of bandwidth that is 9600 Kbs separated into 2 data channels, one for low speed data and one for the voice data.
DMR uses 12.5 Khz that is split in half, one for time slot one and one time slot two.
System Fusion uses either 6.25 or 12.5 Khz. In regular voice mode, 6.25 Khz is used. If you are sending data and talking or are using the mode called voice wide then you are using 12.5 Khz
Concurrent Voice Channels
DMR is the only mode that can support more than one voice channel at a time. It can support 2 different voice channels in the same 12.5 Khz bandwidth. DMR refers to these as Timeslot 1 and Timeslot 2.
All of these modes have Forward Error Correction (FEC) but not all of them are created equal. From my experience DMR has the best and can recover from bit errors quickly making for a great sound. Fusion is a close second with great sound, especially in Voice Wide mode. D-Star trails behind them, If you are on the fringe and get some packet loss D-Star like the other modes puts out something unintelligible (called by Many R2D2). However, D-Star takes longer to recover when that happens than the other modes.
Mixed Mode Repeaters
D-Star does not support mixed mode at all. It is digital all the time. DMR and System Fusion both do but not equally.
DMR can run in mixed mode but when you setup to support both analog and digital you lose the networking ability that makes these digital modes so compelling.
System Fusion was designed to support mixed mode. Their plan is to replace aging analog repeaters with one that can do both analog and digital in the hopes that people would start using digital because it was there. Because of that, their handling of mixed modes is great. There are lots of options around how the repeater handles it and there is transcoding from one to the other, etc.
Ease of Multi-User
I wanted to add this to the end because this is one thing that really bothers me. On both D-Star and System Fusion, when you ask the repeater to connect to a different location, anyone that is listening on that repeater hears that you are there and can tell you have moved the repeater. If they want to move it, it is proper etiquette to ask if the channel is in use and if not go ahead and link it somewhere else.
In DMR this is not the case. DMR uses talk groups and the repeater operator specifies which talk groups are on which timeslot and which ones are connected full time or (pinned up). On your DMR radio you select what talk group you want to listen to. However, say you want to listen to North America and that talk group is not pinned up all the time, you have to tell the repeater by keying down on that talk group.
The C-Bridge then will stop sending the current talk group to the repeater and start sending North America. It will keep sending North America until either there is no activity from the repeater on that talk group (you do not key down for a period of time) or someone requests a new talk group.
So you are listening and having a QSO on North America and suddenly it is like the person you were talking just stopped talking. So while you are having a QSO on North America, I key down on TAC310 to talk to my friend. I unknowingly just took over the repeater, disconnected you from North America and told the C-bridge that the active talk group is now TAC310.
You do not know what happened and I do not know that it happened. I have had this happen to me a couple of times. If the repeater is not busy and with lots of people then the likelihood is lower but in large metropolitan areas the repeaters are busy and it happens.
With DMR, you have to setup a scan so that you can scan all of the possible talk groups on the repeater, but if you do not like one of the talk groups because it it too busy, etc and do not scan it, the likelihood continues.
I just went down a long list good and bad things about each mode. There is not one that stands out above the other, they are all legitimate modes, you have to decide what is right for you.
I assume if you read this far you are likely one of 2 people. An amateur radio operator that is investigating the digital modes or maybe a club or repeater organization considering putting up a new digital repeater or replacing an existing one with a digital mode. I will break this down into some things to think about for each
Amateur Radio Operator
The first thing you should do is go to repeaterbook.com and check to see what types of digital repeaters are around you. More than likely you would want to pick a mode that you can use in your area. You may live in an area that has all of the modes available or may live in an area that has none.
If you live in an area that has none, then your only option for DMR or Fusion is to look at the DV4Mini. For D-Star the DV4Mini is still an option but if you do not want to spend the money on a radio and the DV4Mini, look into some of the USB dongles. If you do not want to dedicate a computer to the job, you could look at putting a DVMega board on the $35 raspberry pi and then you can walk around your house with an HT talking all over the world.
If you live in an area with all of the modes, you have a harder decision to make. If you like flexibility,extendability and/or love to experiment, shy away from DMR and for experimenter, get closer to D-Star.
If you want to be able to just turn it on and not have anything confusing (after it is setup) look at DMR. DMR radios have 2 knobs, volume and typically a 16 channel knob. You pick the talk group from the channel knob and that is it.
Club or Repeater Group
From a Club or Repeater Group you have to first think about it’s purpose. Is it mainly for the club members to Ragchew and talk to people around the world or are you looking at more as a communication system when SHTF. If you are looking more towards an emergency communication system then I would look at DMR. It is much more controllable. You can setup talk groups for the different agencies and groups. If you are going to have more than one, I would setup your own C-Bridge on your network so that if there is some kind of natural disaster your repeaters remain connected but when all is good you can still enjoy the communication to the outside world.
If you do decide to go DMR, the question is do you go UHF or VHF. The biggest reason I have seen for people going VHF is because the repeater group or club already have a VHF repeater and by sticking to the same band, the DMR radio can be setup for analog and still use the repeaters in the same band.
Also, really think out your talk group layout. You can put talk groups on either timeslot. It might be that you put a local (across your repeater system) talk group pinned up on time slot 1 and on time slot 2 you use for things like TAC310, etc.
In DMR, the etiquette is, you make contact on the larger talk groups like US Nationwide but for an extended QSO you move to a Talk Around Channel (TAC) so that the US Nationwide is free. This can be the same etiquette you apply to your own talk group for your organization.
Ok, so you are wanting it more ragchew, fun and experimentation….
Is it going to replace and existing repeater? If so, how busy is the repeater? If you have regular users, how are they gonna feel if you replace it with a repeater that only does digital? Keep that in mind. At the same time, adoption of digital is slower if you give them the option of using both analog and digital on the same repeater.
Does the repeater site have internet connectivity? If not, there really is only one option of the 3 modes that will get you connected to the world without internet. That is System Fusion. The Wires-X box that connects to the internet does not have to be directly connected to the repeater. For D-Star and DMR, you have to have an internet connection at the repeater.
Assuming you have internet, is the main purpose so you can connect outside your area and connect to groups of other repeaters? If so, D-Star is the way to go. It is the best connected, most resilient Mode of the 3 and it is also the most flexible. Fusion is a distant 2nd with DMR after it. I only say that DMR follows Fusion because it is not flexible but fixed in what it provides. Meaning you cannot decide to connect to Germany today, Australia tomorrow, etc unless the repeater has talk groups already present for them.
There are lots of things to think about and much of it is confusing at first.
You can never predict the future, especially when it comes to technology. My best guess would be that Fusion is going to struggle and may go the way of BetaMax. D-Star it still growing quickly and I do not see that stopping anytime soon. DMR is growing in pockets too. It seems the DMR people are hardcore and are a lot of professional radio people that like the Motorola hardware.
I do not want to predict a winner of the modes as I hope there is not a single winner. DMR has a ways to go to catch up with D-star as far as footprint, users and especially the extendability. However, DMR is the perfect solution for some people and that is awesome.
I said in the beginning that not until the end will you know my preferred mode. If I did an objective view in this blog post you should still not know….
My goto when not analog is D-Star. I have a D-Star radio in my car, a couple of handhelds, base stations. However, that being said, I have 3 HH DMR radios, a fusion HH, etc. I use all of the modes. When at home I have a house based D-star hotspot, a portable D-star hotspot with battery, charger and cellular modem, a 20 watt D-Star hotspot, a DV4Mini running DMR and a DV4Mini running Fusion. So I give all modes equal time. I sit here at my desk with a HH for each mode right here.
Most of my friends are on D-star, in fact we get on D-star to talk about DMR. Not because DMR is bad, it is awesome (except for what I mentioned above about taking over talk groups). But I cannot reach a real DMR repeater from my basement where my office is so I have to use the DV4Mini. However, that uses the Hytera network and some of us use a repeater which is DMR-Marc and some us DV4Mini. On D-star, everything connects, there are no different networks so it is just easier.