Digital Formats and a few questions

[Romer]

I am looking at upgrading my HAM setup and was trying to educate myself on Digital Modes

There are 3, D-STAR, DMR and Fusion. There is no single standard

ICOM and Kenwood make radios for D-STAR. Yaesue makes the Fusion system and DMR is more widely used

It wasnt clear to me what this mode does vs what one to get when buying a radio. It looks like Digital quality communication and high speed Data and voice communications. After reseraching and finding the links below some things are not clear to me

1) Is this mode for repeaters only or will it improve communication in simplex between two radios running the same system?


This article was helpful. No real winner here. From what I read I could easily pick the Fusion. Seemed to me D-STAR or Fusion and thats back to the Kenwood and Yaesu


http://www.mikemyers.me/blog/2016/2/19/d-star-dmr-fusion-which-is-right-for-you-7nhdl

also very few repeaters of either type (use special modes)
https://www.repeaterbook.com/index.php

This seems to be banking on wider use in the future

here is a good write-up on System Fusion
https://systemfusion.yaesu.com/what-is-system-fusion/

So without a repeater and say you are stuck 4 hours to the south in a snow storm, would this provide any benefit?

 

[DaveInDenver]

D-STAR and Fusion are both amateur specific. Yaesu invented Fusion and retains ownership of it. D-STAR was invented by the JARL (The Japanese Amateur Radio League), so it's not really owned by any one company. DMR is also an open standard, being invented by ETSI (European Telecom Standards Institute). In it's basic form it's also not owned by one company, although Motorola extended it and called it MotoTrbo. The majority of what we use DMR for isn't proprietary to anyone (for example Motorola can encrypt, which isn't legal for ham anyway).

There are other digital protocols, NXDN, P25, TETRA are also common in commercial world. P25 (Project 25) for one, which is what most public service uses and is also a public standard specific owned by APCO. Kenwood does NXDN for their commercial offerings.

There are pros and cons to each type, so it's more than just being digital. The main advantage to digital modes is you use less bandwidth to achieve a particular fidelity. Our FM radios in amateur radio use 25KHz for each channel which allows as much as +/- 12.5KHz deviation (we usually use +/-8KHz deviation). This is fairly wide band (about half what a commercial FM broadcaster uses) and why it sounds so much better than AM CB.

But this doesn't allow a lot of channels in a limited space, so the FCC dictated that commercial radios reduce that by half. You'll hear that referred to the narrow band mandates. Manufacturers complied and make analog radios that do this but it does start to really sound tinny.

By encoding and using a digital signal you can use the bandwidth more efficiently, turning a 6 KHz signal into 4800 bit/sec data stream you get a bit better fidelity with the benefit of being able to tack on data, nominally call signs, routing, GPS data, that sort of thing. What gets included depends on the protocol.

D-STAR and Fusion use a 12.5KHz channel and frequency divides two streams into the channel. DMR uses the 12.5 KHz channel for two digital voice streams, which are time divided. So at minimum using digital for ham lets us double the number of people who can use the spectrum without a significant loss in fidelity. Digital voice doesn't sound as good a full width FM signal but it very listenable and much better than a halved deviation FM (which would sound like FRS for example).

There is no clear digital voice mode hams use. DMR caught on since it is common in commercial radios so there's a lot of Motorola and competitors using it. Motorola extended it primarily by linking repeaters together over IP, which is pretty cool. D-STAR can link repeaters through reflectors but it's more clumsy since it was developed before the Internet was quite as wide scale. Fusion repeaters can also be linked but I'm not sure the mechanism.

OTOH, D-STAR and Fusion are tailored for ham, so your radio is identified by your call sign. DMR radios are identified by a unique code that isn't your call sign so that data is kept in a database, which assigns radio IDs to call signs (I have personally have two DMR radio IDs). It's not nearly as obvious how to get a DMR radio on the air as a result and in any case all the modes take more configuration than just turning on an FM radio. But if you understand how to program repeaters and set up a computer it's not really that much harder to do.

So without a repeater and say you are stuck 4 hours to the south in a snow storm, would this provide any benefit?

This question could be asked any time. Repeaters and other hams listening is what make the whole thing work.

That's mainly why I bought DMR radios. All the guys in Northern Colorado were getting them and repeaters were going up. So there was someone to talk to. Nationally and globally it's growing with all the linked repeaters so it seemed fun. D-STAR has an established user base but there aren't nearly as many repeaters in Colorado.

Fusion is getting an installation base but Yaesu's repeaters are dual mode, meaning they switch between analog FM and Fusion automatically so having a Fusion repeater is no guarantee anyone is actually using it for a digital mode. It's just capable of it so if you call in digital it will repeat digitally and anyone around who has Yaesu radios will have their radios switch to Fusion, too. But if I use the repeater for analog with a Kenwood or some other brand the whole system switches back to analog, too.

 

[DaveInDenver]

It looks like Digital quality communication and high speed Data and voice communications. After reseraching and finding the links below some things are not clear to me

1) Is this mode for repeaters only or will it improve communication in simplex between two radios running the same system?

So without a repeater and say you are stuck 4 hours to the south in a snow storm, would this provide any benefit?

The main reason for digital voice is bandwidth reduction. But along with that comes the ability to have sub-channel data. Another benefit to digital is it uses the transmitter more efficiently. You're not transmitting dead air so HT batteries last a bit longer.

Beyond that the site connect feature of DMR is why I like it. It's easy to jump in and out of talk groups. D-STAR and Fusion aren't quite the same in this regard. You can make wide area links but they aren't pre-confgured but more ad hoc. There are state-wide and regional DMR talk groups, subject specific (such as off highway and "overland" ones). Once you have your information packetized putting on the Internet is simple.

FWIW, there are now 2,600 DMR repeaters globally tied into the Brandmeister network. You can in theory talk on all 2,600 of them at once with an all call. But they are filtered down by how they are configured. Ones in Colorado will be linked to others in Colorado using talk groups for that.

https://brandmeister.network

There's also the Rocky Mountain Ham DMR systems. They are not on the Brandmeister network yet (and notably there isn't a RMHam DMR repeater in Grand Junction yet and I can't reach the Rangley one).

https://www.rmham.org/wordpress/dmr-radio-site-information/

To our use here there's nothing that really stands out as better or worse. They are all compromises. The main problem with Fusion is it's Yaesu and Yaesu only. D-STAR and DMR don't lock you to one manufacturer. There are many very cheap DMR radios out there, under $100 now. D-STAR is still only Icom and Kenwood and limited models at that. My $0.02 is from a future proofing sticking with an open protocol makes more sense. Yaesu gives the protocol away by retains licensing of it, so it'll always be controlled by them.

 

[DaveInDenver]

Also, there's a RepeaterBook app that lets you find repeaters around you filtered by band, mode and digital protocol. It's very handy.

 

[Romer]

Thanks Dave, that is very helpful

 

[Mendocino]

Thanks Dave, as expected, you added lots of value. On the net-net, I'm happy with my new TM-D710G. I'll be happy when I have the APRS set up and also can use EchoLink and Packet.

When we had the extreme eventing business, we used DMR, but that was mainly a geeky exercise.