microwave
Member
Has anyone compared all three digital voice modes? I'm unhappy with the Dstar quality. P25 sounds good with a new DSP and I haven't tried DMR. What are your experiences with voice quality?
"From what I have experienced with D-Star you'll have to be next to the repeater if you have a handheld or if you have a mobile d star capable radio you'll have a better chance accessing the system. The audio is some what garble or R2/D2 robot voice when someone isn't close enough."
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You have identified a fundamental problem with D-Star.
The format is inferior in that it doesn't re-sync immediately when the signal drops out. You can demonstrate this issue easily - while listening to a D-Star transmission, simulate a drop-out by disconnecting your antenna and then quickly reconnecting it. The audio will be gibberish for three to five seconds until re-sync finally occurs.
The commercial formats re-sync almost immediately. In the case of P25, that is a part of the standard and a required conformance test.
This issue makes D-Star hugely inferior to the commercial digital modes for mobile and portable operation where fading and drop-outs are inherent. The second rate performance of D-Star compared to the commercial formats is part of the reason for the growing amateur interest in DMR and NXDN. They just flat-out work better.
NXDN is popular in my area but when I try to talk to the locals on NXDN it's like talking to the dead silent but when someone else is talking everyone responds. Audio is nice.
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I just starting doing stuff with NXDN. If you are able to get on the WW network, I'm usually listening later at night after 9pm. I've been on around commuting times, too. I've found to make contacts I have to be persistent.
"From what I have experienced with D-Star you'll have to be next to the repeater if you have a handheld or if you have a mobile d star capable radio you'll have a better chance accessing the system. The audio is some what garble or R2/D2 robot voice when someone isn't close enough."
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You have identified a fundamental problem with D-Star.
The format is inferior in that it doesn't re-sync immediately when the signal drops out. You can demonstrate this issue easily - while listening to a D-Star transmission, simulate a drop-out by disconnecting your antenna and then quickly reconnecting it. The audio will be gibberish for three to five seconds until re-sync finally occurs.
The commercial formats re-sync almost immediately. In the case of P25, that is a part of the standard and a required conformance test.
This issue makes D-Star hugely inferior to the commercial digital modes for mobile and portable operation where fading and drop-outs are inherent. The second rate performance of D-Star compared to the commercial formats is part of the reason for the growing amateur interest in DMR and NXDN. They just flat-out work better.
N8OHU: "Part of the reason that D-Star doesn't resync properly is..."
You observations may have merit, but if so, they constitute additional D-Star weaknesses beyond the flawed "air interface".
The lack of re-sync on signal drop-outs affects even simplex radio-to radio transmissions, and thus has nothing to do with reflectors, other than the fact that they will "reflect" the incoming data errors from signal issues on the initiating user's transmissions.
As you note, hams are adding innovations to D-Star. Reflectors are an example of this - which illustrates the fact that, as conceived by JARL, D-Star doesn't fit US amateur operations very well.
It's sad that we didn't have domestic leadership participating in the development of a digital voice format with enough versatility to meet everyone's needs worldwide and based on the highest technical standards.
It's also unfortunate that so many innovations are being developed for D-Star when that effort could have been invested in a format with a real future. It's kind of like building a beautiful new house on former marshland. Sooner or later folks are going to see the that the foundation is settling and notice the cracks in the walls.
I sold off my NXDN radio I just didn't like how the locals wouldn't speak to me but they would speak to someone else. It's clicklish on some of the repeaters around here. :roll:
The biggest stumbling block for many hams with TRBO is the price of the programming software, and now the entitlement key requirement if you wish to program wideband, even in the ham bands- other manufacturers like Kenwood allow current radios to be programmed for wideband only in the HAM portions of the VHF and UHF bands (this is the case on my TK-2312). Programming software is also cheap and widely available from Kenwood, Icom and Vertex for their DMR and analog radios. This is why NXDN/iDAS has taken off at quicker pace, it's more ham friendly to the wallet.
That being said, there is no question that DMR has the best audio quality compared to NXDN and D-star. D-star is to venerable to QRM as has been discussed. I wonder how much gas there is left on the D-star bus?
It's too bad the Vertex eVerge DMR radios do not support IP connect. They would be a perfect way for hams to get into DMR for less than many D-star radios cost, and they use the same programming cables (portables at least) as the Yaesu ham rigs. Dealers are pretty liberal with "helping" buyers get software as well.
JRayfield: "We did have "domestic leadership participating in the development of a digital voice format with enough versatility to meet everyone's needs worldwide and based on the highest technical standards".
It's called DMR...."
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I guess I thought I was clear enough since the format being discussed was D-Star.
Apparently not, so it should have read:
It's sad that we didn't have domestic leadership participating in the development of an amateur radio digital voice format with enough versatility to meet everyone's needs worldwide and based on the highest technical standards.
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The point is that amateur radio in the US is stuck with a digital voice format developed elsewhere, one which not only needed extensions to fit US ham's operational desires but one which is technically deficient - it just doesn't work very well at the basic air interface level.
This has driven knowledgeable hams to adopt commercial formats such as DMR and NXDN along with P25. DMR appears to be the winner in this so far and had Yaesu chosen DMR for their new digital ham radio they would have become a serious threat to the future of D-Star.
Sadly, they did not, thus earning the scorn of countless US hams who have no need whatsoever for yet another incompatible digital voice format.
JRayfield: "We did have "domestic leadership participating in the development of a digital voice format with enough versatility to meet everyone's needs worldwide and based on the highest technical standards".
It's called DMR...."
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I guess I thought I was clear enough since the format being discussed was D-Star.
Apparently not, so it should have read:
It's sad that we didn't have domestic leadership participating in the development of an amateur radio digital voice format with enough versatility to meet everyone's needs worldwide and based on the highest technical standards.
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The point is that amateur radio in the US is stuck with a digital voice format developed elsewhere, one which not only needed extensions to fit US ham's operational desires but one which is technically deficient - it just doesn't work very well at the basic air interface level.
This has driven knowledgeable hams to adopt commercial formats such as DMR and NXDN along with P25. DMR appears to be the winner in this so far and had Yaesu chosen DMR for their new digital ham radio they would have become a serious threat to the future of D-Star.
Sadly, they did not, thus earning the scorn of countless US hams who have no need whatsoever for yet another incompatible digital voice format.
xmo said:...had Yaesu chosen DMR for their new digital ham radio they would have become a serious threat to the future of D-Star.
Sadly, they did not, thus earning the scorn of countless US hams who have no need whatsoever for yet another incompatible digital voice format.
Boatanchor said:Lots of people 'invested' (wasted) large sums of money on D-Star and P25 radios, only to later end up selling the gear for a third the price they paid, to some other sucker.
It was/is all hype IMHO.
+-5Khz FM gives better audio quality (under most signal conditions), cheaper repeater setup & running costs, universal access to cheap equipment and really, I don't see any compelling reason to go down the public safety path and be royally screwed over at every turn.