Why all the fuss about DStar?

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#1
Keeping in mind that I'm a newbie at all this, I have a question that might seem a bit silly.

I've been reading threads about DStar and other similar digital modes and had to use google to see what's going on and how this stuff works.

I spent a month learning how to decode the various digital modes on HF frequencies. Learning how to recognize PSK31, used software to decode CW, and about a dozen other modes that all reminded me of my days with a 2400 baud modem and a dial up connection to my prodigy account. I found the data transfer modes fascinating and spent quite a few hours listening and decoding to learn the in's and out's of it all. I decided that using the PSK (and other) digital modes could be really useful.. that is, if the internet or my phone ever stopped working.

I got into the Ham radios because I wanted a standalone communications capability.. The ability to talk to the outside world (both local and long distance), that didn't depend on any infrastructure except my own. In fact, I thought that was what ham radio was all about.

Along comes these other digital modes like DStar that inevitably require a repeater and an internet connection.

So my next thought is why? Why would someone spend the money on an expensive ham radio that requires 3rd party infrastructure when you can just pick up your smart phone and do the same thing (only better) at a fraction of the price?

Do I have a misunderstanding? Am I missing something?

Seems to me, and I hope I'm mistaken, that they're slowly morphing radios into smart phones. If I find an iHam at the apple store, I'm going to be disappointed.
 

W9BU

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#2
Ding! We have a winner! If all that digital voice on amateur radio offers is repeater linking, we already have that with AllStar Link, Echolink, and IRLP for analog repeaters. And, before those Internet-based systems existed, repeater owners were linking to adjacent analog repeaters using RF links on higher frequencies.

If a digital voice mode offers the ability to move data including voice, then I would consider that a plus. D-STAR has the capability, but the data throughput is fairly slow. DMR supposedly has this capability, but I don't think anyone is using it. Yaesu System Fusion has the capability to transport low-resolution images, but Yaesu officials have made it clear that data is not their focus.

The original plans for D-STAR included a linking system using amateur radio allocations at 10 GHz. I don't know that that idea ever really got off the ground and I don't know anyone who is using it.

I don't have an answer to your question of "why?". Yeah, it's amateur radio from your radio to the nearest repeater, but it's the Internet from your repeater to the other repeater. And, with the proliferation of "dongles" and "hotspots", you don't even need to use a repeater. You just talk to your hotspot at home or in your car which is connected to, you guessed it, the Internet. Another answer is "experimentation". But, all of these digital voice modes along with all of the hardware and networking protocols have been developed by large corporations. The only "experimentation" that I can see is figuring out how to configure your radio, your hotspot, or your repeater. And, since everyone who buys a new DMR radio immediately goes on-line asking for someone else's "codeplug" to program their radio so they don't have to figure it out themselves, then where is the personal "experimentation"?

Don't take my opinion as gospel, though. I'm not a fan of digital voice modes mostly because I simply don't see the point. Also, I think that DV is further segregating amateur radio. There are 700,000 licensed amateur radio operators in the U.S. Only a subset of that number ever get on the air on a regular basis and only a subset of that number ever use repeaters and only a subset of that number ever get involved in one of the three popular, but mutually incompatible DV modes. For the record, I own D-STAR and System Fusion equipment...that I rarely use.
 

AI7PM

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#3
Along comes these other digital modes like DStar that inevitably require a repeater and an internet connection.
They do not require an "internet connection". That bit of misinformation refuses to die.

I use a DMR system that is microwave linked into three states. The internet can die, and it would keep on working. Same goes for the analog repeater network, which is now moving to digital link radios. Better audio and dependability in the system, and the analog repeaters are still analog.

All of the digital modes will operate simplex, or via a repeater, just like analog.

Now, if one wants to chat around the world via digital HT, then yes, a dongle or repeater with an internet connection will be necessary. Great for those in assisted living facilities and few transmissions left to make. Great for those in antenna restricted situations such as apartements or condos.

I prefer HF for long distance/international contacts. Just me, my battery, and some wire. Did you know you can use DSTAR on HF? No internet, no repeater. Just radio, battery, and wire.
 
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#4
They do not require an "internet connection". That bit of misinformation refuses to die.

I use a DMR system that is microwave linked into three states. The internet can die, and it would keep on working. Same goes for the analog repeater network, which is now moving to digital link radios. Better audio and dependability in the system, and the analog repeaters are still analog.

All of the digital modes will operate simplex, or via a repeater, just like analog.

Now, if one wants to chat around the world via digital HT, then yes, a dongle or repeater with an internet connection will be necessary. Great for those in assisted living facilities and few transmissions left to make. Great for those in antenna restricted situations such as apartements or condos.

I prefer HF for long distance/international contacts. Just me, my battery, and some wire. Did you know you can use DSTAR on HF? No internet, no repeater. Just radio, battery, and wire.
Thanks for the reply.. and now the questions..

Can two stand alone radios use DStar between themselves? Or does DSTAR require a repeater? IE: a third party?

So what kind of performance increase would be expected if two DSTAR radios wanted to communicate with each other in the absence of any other supporting infrastructure like repeaters? Would the signals be better than regular analog?

If the Dstar operates better than analog, and can do it without any other infrastructure, then I can see a benefit.
 

W9BU

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#5
Can two stand alone radios use DStar between themselves?
Yes.

With analog radios, as the signal strength at the receiver decreases, the noise component in the decoded audio increases. This change is gradual and the noise will keep getting worse and worse as the signal gets weaker and weaker to the point where the decoded audio is all noise.

With digital radios, there is a bit of a "digital cliff" in that the decoded audio stays basically the same as the signal strength decreases until you fall off the cliff and there's no longer enough signal to decode anything intelligible.

Also, digital radios are subject to brief drop-outs. No radio path is perfect, except in controlled laboratory conditions. A brief spike of interference might cause a digital radio to drop a syllable or two until the bit stream resumes. Some digital schemes have enough error correction to make that dropped syllable hardly noticeable. Analog radios experience these same drop outs, but our brains are pretty good at filling in the blanks with something reasonable. Often times, though not always, our brains are better at this pattern reconstruction than the digital voice radios are.
 
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#6
Yes.

With analog radios, as the signal strength at the receiver decreases, the noise component in the decoded audio increases. This change is gradual and the noise will keep getting worse and worse as the signal gets weaker and weaker to the point where the decoded audio is all noise.

With digital radios, there is a bit of a "digital cliff" in that the decoded audio stays basically the same as the signal strength decreases until you fall off the cliff and there's no longer enough signal to decode anything intelligible.

Also, digital radios are subject to brief drop-outs. No radio path is perfect, except in controlled laboratory conditions. A brief spike of interference might cause a digital radio to drop a syllable or two until the bit stream resumes. Some digital schemes have enough error correction to make that dropped syllable hardly noticeable. Analog radios experience these same drop outs, but our brains are pretty good at filling in the blanks with something reasonable. Often times, though not always, our brains are better at this pattern reconstruction than the digital voice radios are.
Ah.. That paints a better picture of what's going on. thank you.
 
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#7
I have D-Star and Fusion radios. I had DMR (radio died). I wasn't particularly enamored with any of them. It's neat simplex. I would say Fusion being my favorite cause you just push a button and you are in that mode (same as you would push USB or AM). I played around with D-Star for a while. It's good that there are options but bad that all the radio operators are spread out over different formats. Tough to find someone at times! Good luck
 

kf6gpe

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#8
I'd like to echo W9BU's comments about the fact that D-STAR (or DMR, for that matter) doesn't necessarily equal Internet.

I'll also say that D-STAR rekindled my interest in amateur radio in a big way. I live in a box canyon, and except for NVIS, very little works (no broadcast radio, very little HF even in the best conditions, and I can reach exactly two repeaters). Setting up an OpenSpot means I can check into some fun nets every week, and although it's not really "working DX" on REF001C the way HF when I go camping is, I can have a lot of nice QSOs with people all over the world from my living room. It's even sparked my wife's interest in the hobby.
 

pinballwiz86

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#9
Why? Because digital voice IS the future for VHF/UHF. Amateur radio USED to be the leader in radio tech...but it doesn't seem to be the case outside of Japan.

I have no idea why that is. People should be trying to advance radio instead of dropping anchor.
 
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#10
Mike Linkletter

Why? Because digital voice IS the future for VHF/UHF.
The digital modes just may be the future. And that may be a good thing.
But my minor wah here in Metro Detroit is that every digital machine has to be linked with out-of-state machines. And with the linking comes the different audio levels. And with the different audio levels, I'm using my volume control like a yo-yo to follow the conversations.

Me personally, I don't care if it's analog or digital. But I just want a local QSO. And this is why FM will be my primary mode for years to come.
 
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#11
I get a kick out of the analog vs digital debate. Yes you can link digital via the internet, same with analog. Yes you can link digital with RF, same with analog. Yes I can simplex with digital, same as with analog. Yes you can have a clear conversation without static using digital, analog not so much (at least not 100% of the time). Yes you can work weak signal with analog (and the ear splitting static will let you know it is a weak signal), weak signal digital will sound just fine until the signal gets too weak.

So to recap, I can do EVERYTHING with digital that you can do with analog, minus the static. Here is what I can do with digital that analog will not:

send data (images)
send data (location)
send data (call sign)
send data (text type messages)

Digital also uses less spectrum. Voice can use 1/2 the spectrum of analog. The rest is usually for data transmissions.

It is also noteworthy that DMR allows for two voice channels per repeater! That is correct two separate conversations at the same time! Analog cannot compete with this one.

It is at this point that the analog only crowd starts a rant that when the zombie apocalypse happens we will have to fall back to analog. I don't know why we would do that. If something happens and the internet goes down, guess what, IRLP goes with it too. Your analog repeater just became local. The exact same thing will happen to a digital repeater. The only difference is in local mode the digital repeater will have clear coms, ability to pass data, in some cases two channel capability, and use less spectrum which also can lower power consumption. All that sounds really great in a disaster, why would you limit yourself to analog?

Besides, all my digital radios can do analog too. I like analog, it has it's place but digital is the future and it is here to stay. With all the MMDVM devices and the advances in programming we are able to trans-code digital signals from one type to another (IE. fusion to DMR). Everyday digital gets better.

Oh well, my two cents that add up to nothing,

73's
Brian
AD0LR
 

pinballwiz86

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#12
The digital modes just may be the future. And that may be a good thing.
But my minor wah here in Metro Detroit is that every digital machine has to be linked with out-of-state machines. And with the linking comes the different audio levels. And with the different audio levels, I'm using my volume control like a yo-yo to follow the conversations.

Me personally, I don't care if it's analog or digital. But I just want a local QSO. And this is why FM will be my primary mode for years to come.
You've been misinformed. Your local D-Star repeater does NOT have to be linked with "out of state machines." The person who set it up linked it to a "reflector" no doubt. If you don't like it, bring it up at the next club meeting and tell them so. They can shut down the gateway and make it local only. But what is the point of that as you already say you have other analog repeaters for your FM communications..
 

belvdr

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#13
You've been misinformed. Your local D-Star repeater does NOT have to be linked with "out of state machines." The person who set it up linked it to a "reflector" no doubt. If you don't like it, bring it up at the next club meeting and tell them so. They can shut down the gateway and make it local only. But what is the point of that as you already say you have other analog repeaters for your FM communications..
I haven't found one yet that is nailed by the administration either. All have the ability to be controlled by the users.
 

pinballwiz86

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#14
I haven't found one yet that is nailed by the administration either. All have the ability to be controlled by the users.
The Gateway can be turned off. Which makes the repeater local use only. One of the main benefits of D-Star is being able to link repeaters together. Not surprising that this feature has been left on.
 

belvdr

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#15
The Gateway can be turned off. Which makes the repeater local use only. One of the main benefits of D-Star is being able to link repeaters together. Not surprising that this feature has been left on.
Correct but even with the gateway on, the users can unlink the repeater from a reflector. As you state, this would not stop DVAP and DVDongle users from connecting though.
 
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