Digital Voice, Why?

[gil]

Not trying to be a smart ass, I swear.. Why the push to digital voice on UHF/VHF? Does it do anything FM doesn't do?

Gil

Sent from my A1-830 using Tapatalk

[vwflyer]

I'm no expert on digital voice. I've never used a radio with it so they don't come less experty than me. From what I understand though, it has very little to do with the quality or range of the actual voice transmission. I think it has more to do the the metadata that can be included in the transmission. Echlink, IRLP, WIRES, etc. all try to create ways of interlinking repeaters so that ham radios can talk world wide and function more like cel. phones but I think this kind of thing is easier to accomplish and implement features and capabilities in the digital realm. That at least is usually the selling point for digital radio in the public safety and commercial fields. Interoperability is the buzzword.

[gil]

Right.. I saw that call signs are included in the transmission, but didn't see much use for digital otherwise... I'll have to look into it a bit more, but I doubt it is worth the extra cost...

Gil.

[cockpitbob]

The manufacturers always have to innovate and do something new in order to stay out front.  But I can see some devious thinking by the manufactures in digital radios.  By making digital incompatible with analog we'll be forced to replace our FT-60s and UV-5Rs.  And right now the manufacturers aren't working and playing well together, meaning Yaesu's stuff isn't interoperable with iComs (last I heard anyway).  If one manufacturer can get their way to be the default standard (think VHS vs. Beta VCR tapes) then all radios will be more expensive because of the royalties paid. 

Personally I'm sticking with analog as long as I can.  I just don't have a real need for any of the features digital radios provide.

[gil]

Same for me... If VHF/UHF become a strictly digital affair, I'll just stop using repeaters.. I have no use for digital voice.

Gil

[vwflyer]

It just so happens that yesterday I was listening to  the podcast "Ham Radio 360" where Rick Zach K1RJZ was talking about DMR. DMR started out in the commercial world and was adopted by hams. These digital commercial radios are dropping in price and a decent one can be had for around $110 USD. That's about half of Icom's cheapest D-Star radio. It works on analog so it's not even a bad deal for buying an analog HT. Use it for analog and if you have a need for DMR someday you already have the capability to use it.

One thing Rick likes about using DMR is that he lives in a rural part of the states where there is very little repeater traffic. Even though there is repeater coverage there are too few people using them to find someone he'd like to talk with. With DMR he can select a channel based on how big of an area he'd like to be heard in. If he goes to the state channel all the DMR repeaters in his state will rebroadcast his call. If he chooses the regional channel on his HT all the repeaters in his state and the neighboring states will open up. He can choose nation wide channel and open every DMR repeater on the network nation wide as far as I understand it. Custom talk groups can be made for whatever the occasion and only people scanning that talk group's channel will hear him. They say that it makes great use of resources because one repeater can handle many talk groups. In a tactical situation (marathon or whatever) you can have a talk group for all the mobil units, one for all medical units, one for all base units, one that everyone can hear, etc. They can all use the same repeater and not have to hear traffic that wasn't intended for them. And because of the way that DMR uses timesharing two talk groups can be using the same repeater at the exact same time and not interfere with each other. If a third talk group tries to talk while two others are already talking he'll probably get a busy signal and will have to key his mic again. If more than one repeater is in the network and within range than his radio can select the repeater with an open channel. If I remember rightly Rick said that theoretically up to four talk groups can use one repeater at once. I'll have to go back and see if he actually said that. As I said earlier I'm far from being an expert and I might have all my facts messed up, but you get the idea. It's not about better sounding voice or anything, it's about being able to talk to who you want to, when you want to, wherever he might be located.

As hams most of us don't have a real need for that but we also don't have a real need to do anything on the radio. We do it because it's fun. If listening to the nation talk group isn't fun don't do it. As far as ways it can be implemented for use in emergency situations, I think it offers some advantages over traditional analog to responders as long as the nature of the emergency doesn't compromise the repeater network.

[cockpitbob]

vwflyer, I see DMR as a double-edged sword.  On the one hand, some jerk can QRM repeaters state wide if he wants.  On the other hand, I'm guessing there is (or will be) the ability for a repeater to "ban" a particular radio.

[vwflyer]

Cockpit Bob, I suppose you're probably right but then who would do a thing like that ::)

[gil]

Interesting, that I can see the usefulness of.. Assuming the repeater owner can indeed ban a specific radio. I could see it being used for a group, if the repeaters aren't too expensive, but if it is commercial gear, there might be many used ones for sale. That guy Rick should be invited here, vwflyer?

I could see a repeater being very useful for a prepper group if it could be located high enough and access could be limited after the SHTF. An HT can reach 30 miles with enough altitude.

The needs to be one standard for sure...

I'll look into DMR... Wondering if they use it here in France...

Gil.

[vwflyer]

Now I remember what he said about 4 simultaneous conversations. He said that because DMR uses half the bandwidth of traditional analog FM, when combined with the fact that DMR lets two conversations simultaneously coexist on one frequency you can fit 4 simultaneous conversations in the same frequency spectrum that one traditional analog FM conversation uses.

You see, you should not listen to everything I say. You'd be better off listening to him yourselves. Here is a link to that episode of the podcast so that you can do exactly that.
http://hamradio360.com/index.php/2016/05/31/ham-radio-dmr-with-k1rjz-digital-mobile-radio/

Like you say Gil, even better yet is to invite him to post here and explain to us how this can be taken advantage of in a disaster scenario. Maybe I will reach out to him and see what he says.

I'll look into DMR... Wondering if they use it here in France...

Seems to me that he did mention what was predominantly being used in Europe but I didn't pay much attention to that part so don't remember what he said there.

The needs to be one standard for sure..

I totally agree. He did say that System Fusion and DMR were very similar modes, they use the same codec or modulation scheme or something. If this is the case maybe the two could eventually be merged into one. System Fusion has an advantage in that it can use wide bandwidth modulation which of course allows for higher data speeds making it capable of sending digital photos and such.

[K7JLJ]

Really? No use? On a prepper board?  It's encrypted text right out of the box.  That's serious comm security


- Jim

[cockpitbob]

Really? No use? On a prepper board?  It's encrypted text right out of the box.  That's serious comm security


- Jim

Oh,....well......there is that, I suppose  ::)

[gil]

It's encrypted text right out of the box.

You're right Jim, that is an important factor. I looked into it a bit more... It is fairly complicated but not so much that anyone wouldn't be able to learn the system fairly easily. I can see how it would be beneficial for a group. Larger groups could even invest in a DMR repeater, those are fairly expensive.

Thanks for reaching out to Rick VWFlyer. We need experts on this forum.

Price is a bit stiff for DMR radios, but I noticed the Tytera TYT DM-390, a Chinese made waterproof UHF handheld for about $170, not much more than an analog Yaesu or Icom.

There are very few DMR repeaters in France, much less than in England, none near my location. That doesn't surprise me. The state of amateur radio in France is pretty bad, probably due to the tendency of the French to over complicate everything for no good reason. London is 150 miles from here.. I'd need a mighty antenna to hit a repeater there! Brussels is about 50 miles, that might work.. Paris is 140 miles...

My local repeater is both on 70cm/2m. The TYT would work fine in analog mode, if it can produce the 1750Hz tone required to open the repeater. I don't know why they don't use CTSS here, it's so much easier.. I'd probably use the radio in analog 99% of the time, but having the digital capability could be useful. Still, I could buy four Baofengs for that price...

Gil.

[vwflyer]

Here is a less expensive one from the same company. I've heard good things about them but they are not Motorolas.
http://www.mtcradio.com/tytera-dmr-md-380-vhf-136-174-mhz-digital-handy-talkie-with-programming-cable-software/

[K7JLJ]

The 380 or 390 was my first choice but there is a new on from Wouxon coming out soon that has a single button switch from analog I to digital.

I only see a simplex use for tactical comms and only worth it at the China prices which are less than or equal to a standard HT ~$150


- Jim