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Digital Voice for Amateur Use Discuss use of digital voice technologies on the amateur radio bands. This is to include technologies such as VoIP, P25, DMR/TRBO, NXDN, D-STAR, etc.

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  #21 (permalink)  
Old 02-06-2013, 6:45 PM
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Originally Posted by Boatanchor View Post
I don't see any compelling reason to go down the public safety path and be royally screwed over at every turn.
Public Safety (meaning Law Enforcement and Fire/Rescue) is only getting royally screwed if they are not purchasing P25 equipment; that is the national interoperability standard as I recall. Also, I don't think they are affected by the mandated narrowbanding, but I could be mistaken on that.
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Old 02-06-2013, 6:50 PM
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I truly hope that Yaesu takes notice of this and takes it to heart.

I really would like to see a decent amateur radio that uses an already in use commercial market protocol.
We've already been down that path with AX.25 Packet, and you know how popular that is right now. I would like to see more innovation with, or based on, the JARL D-Star specification, which will continue to grow as Ham Entrepreneurs like Northwest Digital Radio and pipeMSG develop new hardware for D-Star and Codec2 digital voice modes.
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Old 02-07-2013, 7:58 AM
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If you really want D-Star to take off, then have Icom sell a dual-mode repeater that will allow analog and D-Star operation. Try and convince your club to drop $3K on a repeater that will require everyone to buy new rigs to operate on because they won't be able to use there current equipment!
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Old 02-07-2013, 9:26 AM
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Originally Posted by N8OHU View Post
Public Safety (meaning Law Enforcement and Fire/Rescue) is only getting royally screwed if they are not purchasing P25 equipment; that is the national interoperability standard as I recall. Also, I don't think they are affected by the mandated narrowbanding, but I could be mistaken on that.
I agree with this, but I don't think amateur radio operators should follow this. We can't talk on their frequencies and they can't talk on ours. So the question of a compatible digital mode really doesn't matter.
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Old 02-07-2013, 9:55 AM
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I don't have a lot of experience with any of them but I'd say that DMR and NXDN are comparable in terms of audio quality. I wouldn't say one is better than the other. IME, when you're fringe NXDN gets noticeably garbled (what is known as the r2d2 effect) whereas DMR doesn't seem to do that but the voices get so distorted that you don't recognize who you're listening to on the other end. So being that I always seem to be fringe where I live, NXDN has a more natural sounding voice quality.
In my limited time as a D-star user, I'd say that d-star takes a close second place to DMR and NXDN.
I've only had very brief experience listening to p25 on an actual p25 radio. It probably sounds the best but that may just be psychological seeing as how I was listening to it on a radio that's worth the combined value of my dstar radio, my 2 nxdn radios and my mototrbo radio all put together and the signal was very strong.

I know the OP didn't ask about anything other than audio quality but there is definitely something to be said for the ease of getting on the air with NXDN. Compared to the others, including D-star, it is the least complicated. Equipment and programming gear is the easiest to come by.
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Old 02-07-2013, 10:25 AM
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Originally Posted by wb0wao View Post
If you really want D-Star to take off, then have Icom sell a dual-mode repeater that will allow analog and D-Star operation. Try and convince your club to drop $3K on a repeater that will require everyone to buy new rigs to operate on because they won't be able to use there current equipment!
Not really needed; it's relatively easy to take an existing analog repeater and convert it to dualmode operation with available hardware and software.
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Old 02-10-2013, 4:39 PM
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Hey all. Personally, i think as to audio quality between P25 and DSTAR, it`s a horse apiece. P25 does sound more "trebbley" than DSTAR does, but that`s just how i hear it, and i`m hearing the P25 stuff on a scanner instead of a P25 radio, and the DSTAR on my `92AD. In some cases P25 does beat DSTAR for nice loud "punchy" audio though. 73. N9NRA
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Old 02-11-2013, 5:47 AM
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Originally Posted by N9NRA View Post
Hey all. Personally, i think as to audio quality between P25 and DSTAR, it`s a horse apiece. P25 does sound more "trebbley" than DSTAR does, but that`s just how i hear it, and i`m hearing the P25 stuff on a scanner instead of a P25 radio, and the DSTAR on my `92AD. In some cases P25 does beat DSTAR for nice loud "punchy" audio though. 73. N9NRA
With digital subscriber radios, the important part to what "sounds" better is all in how the subscriber radio DSP works- and how well it is setup.

My experience is with P25 phase 1 and DMR radios- but both of them offer multiple options in their programming software to tailor the audio response to the user's preference or the intended use. The LMR radios typically have superior performance than D-star radios because of this, but then we are talking about tools versus toys. The LMR radios are also kept current (or should be by their users!) with DSP and firmware updates which can affect performance greatly. Only on the later D-star radios has Icom bothered to make firmware updates available.

I've yet to see a D-star radio that gives anywhere near the fidelity and RX audio quality of even the lowest price LMR digital radio. So it's really hard to compare the two.

But the lack of syncing during packet loss is a big loser. When D-star users get multipath or short fades, the audio loss is 3-5 seconds. This doesn't happen on NXDN, DMR or P25 phase 1.

Rapidcharger, keep in mind when you heard P25 phase 1, you were listening to a system using CQPSK-LSM simulcast from 7 sites, one of which was about 2 miles away- with an ERP of a quarter kilowatt- on a system that you and your fellow taxpayers shelled out around $32 million dollars for (not counting the $300K a year maintenance fees) and on a radio that, as you said, has a street price of around $2800 (your county paid more than that though in 2007!).
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Old 02-11-2013, 5:50 AM
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Originally Posted by N9NRA View Post
Hey all. Personally, i think as to audio quality between P25 and DSTAR, it`s a horse apiece. P25 does sound more "trebbley" than DSTAR does, but that`s just how i hear it, and i`m hearing the P25 stuff on a scanner instead of a P25 radio, and the DSTAR on my `92AD. In some cases P25 does beat DSTAR for nice loud "punchy" audio though. 73. N9NRA
When you hear P25 phase 1 on an actual subscriber radio, setup correctly, with current DSP and software, you will be ashamed of how lousy the D-star radio sounds. I think it is more the fault of the typical "cheap ham toy" radio design with a vocoder stuck on the end of the audio chain.

This of course, if your local P25 system is optimized and not some poorly maintained POS. We have one of those in my area- it's amazing no one has lost their life because of it either.
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Old 02-11-2013, 7:20 AM
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As MTS2000des says, the NX-300 from Kenwood I have that I use for amateur radio NXDN has multiple options for both receive and transmit equalization. At first, I was talking to someone and they said my audio wasn't sounding right. They advised me to change the settings to match how theirs was set up, and they said my "digital voice" sounded very close to my "analog voice".

The commercial rigs do sound very good. I sold off my D-Star radio 3 years ago. Now that I've heard the commercial digital formats, I am sticking with them. At least in parts of New England, we have DMR, P25, and NXDN systems, and some are linked to worldwide networks.
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Old 02-11-2013, 8:21 AM
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I hate to say it but the more I listen to and use DMR and NXDN and DSTAR, the more I think analogue sounds a lot better to me in terms of sounding "natural." Assuming you've got a strong signal, that is. The rest if it kinda sounds like nextel.
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Old 02-11-2013, 5:04 PM
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Quote:
Originally Posted by rapidcharger View Post
I hate to say it but the more I listen to and use DMR and NXDN and DSTAR, the more I think analogue sounds a lot better to me in terms of sounding "natural." Assuming you've got a strong signal, that is. The rest if it kinda sounds like nextel.
Wait til you meet someone in person that doesn't sound anything like they do on the radio...
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Old 02-11-2013, 8:24 PM
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rapidcharger:
"I hate to say it but the more I listen to and use DMR and NXDN and DSTAR, the more I think analogue sounds a lot better to me in terms of sounding "natural." Assuming you've got a strong signal, that is...."
---------------------------------------------------------------------------------------------------------------

The three commercial formats and D-Star have one thing in common which is the use of DVSI's VOCODER technology. As a result, they share similar audio quality characteristics with differences as discussed in this thread - primarily the superior faded signal performance of the commercial formats and their more sophisticated audio processing.

The exceptionally low data rate of the DVSI VOCODERs is not achieved without a cost and that cost is that the resulting audio quality is slightly lower than the best analog audio. The big advantage of the digital modes - beyond added features associated with digital such as embedded signaling - is that the audio quality is consistent throughout the system's service area.

Most of the radio vendors show this in a graphic that looks something like the following. Note that the vertical scale is in terms of DAQ which = Delivered Audio Quality. This is a subjective measurement of the intelligibility of the audio on a scale of 1 to 5 with 5 being completely understandable and 1 being unreadable. This is a subjective measurement - similar to MOS which is often used in telephony [MOS = Mean Opinion Score].
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Old 02-13-2013, 7:03 PM
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Default DMR wins hands down

I have used D-Star, DMR (Mototrbo/Hytera), and P25; DMR wins for audio quality, Phase 1 P25 is second, and D-Star is a distant third.

I have the feeling that Phase 2 P25 may be much closer to the DMR quality and possibly equal.
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Old 02-14-2013, 2:31 AM
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In reference to the chart above, That is in theory how the different in signal quality works. However, My friend and I tested once, between my NXDN radio in my vehicle, and his NXDN radio in his vehicle.
Using the same power, same frequency, we were able to receive digital voice, but when we switched to analog, when could even break the squelch on each others radio. So in our real world tests, the 6.25 NXDN signal physically traveled farther than the wideband analog signal. These tests were done with F6121 UHF radios and 5db NMO mounted antennas, verified to work very well already on the local analog ham repeaters.
So in short, I have found that digital goes farther than analog, and maintains intelligible voice.
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Old 02-14-2013, 4:32 AM
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Originally Posted by stevelton View Post
In reference to the chart above, That is in theory how the different in signal quality works. However, My friend and I tested once, between my NXDN radio in my vehicle, and his NXDN radio in his vehicle.
Using the same power, same frequency, we were able to receive digital voice, but when we switched to analog, when could even break the squelch on each others radio. So in our real world tests, the 6.25 NXDN signal physically traveled farther than the wideband analog signal. These tests were done with F6121 UHF radios and 5db NMO mounted antennas, verified to work very well already on the local analog ham repeaters.
So in short, I have found that digital goes farther than analog, and maintains intelligible voice.
I had the opportunity to do a test for a local government agency using a mixed-mode NXDN repeater (UHF) installed at my site.

From the fringe, on analog- audio was exactly as you described- almost no detectable carrier- yet switching modes (the vendor programmed the NX-800's for dual mode 12.5KHz) , the NXDN audio came through perfect copy, and I did not even notice any "Max Headroom" effect.

I would concur that digital CAN certainly outperform analog in weak signal areas. Does analog FM have superior fidelity? Of course, in a perfect analog world- when S/N is strong and no interference is present. How often do those conditions exist "in the real world"?
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Old 02-14-2013, 10:38 AM
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I read somewhere that the Florida NXDN ham guys had interfaced a Heil mic to an NXDN radio, and near analog audio quality. I think between a better mic, and future refinement of the NXDN hardware, we could see in the next 3-5 years NXDN with almost analog clairity, much like the difference between 1st generation digital cell phone and what we have today.
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Old 02-16-2013, 6:55 PM
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Originally Posted by shmget View Post
As MTS2000des says, the NX-300 from Kenwood I have that I use for amateur radio NXDN has multiple options for both receive and transmit equalization. At first, I was talking to someone and they said my audio wasn't sounding right. They advised me to change the settings to match how theirs was set up, and they said my "digital voice" sounded very close to my "analog voice".
A lot of people don't see the need to make these kinds of adjustments on the Ham equipment that does support it; I've seen numerous derogatory comments made on the FT-817 Yahoo Group whenever one of the guys that supports audio adjustments on that radio offers to help someone fine tune theirs. I'd love to see it become a standard feature on newer VHF/UHF Ham gear.
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Old 02-16-2013, 8:27 PM
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P25 kicks DMR's butt.
DMR kicks analogue's butt.
That is my conclusion.

In case there is still any confusion, here's an illustration.
DMR ---><---P25

ANALOGUE ---><---DMR

Any questions?
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Old 02-16-2013, 8:29 PM
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Originally Posted by stevelton View Post
I read somewhere that the Florida NXDN ham guys had interfaced a Heil mic to an NXDN radio, and near analog audio quality. I think between a better mic, and future refinement of the NXDN hardware, we could see in the next 3-5 years NXDN with almost analog clairity, much like the difference between 1st generation digital cell phone and what we have today.
Steven
Absolutely. Hardware makes a world of difference.
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