Differene between DPMR and DMR

[teufler]

Reviewing radios that are available on the market, I see two that are "close to initials", but have no idea how they are different or they are just the same. Can somebody expl;ain the difference??

 

[nd5y]

https://en.wikipedia.org/wiki/Digital_mobile_radio
https://en.wikipedia.org/wiki/Digital_private_mobile_radio
DMR Association | The DMR Standard
dPMR - Technology Benefits

 

[jaspence]

dpmr vs dmr

DMR versus dPMR comparison

The link above gives you a good comparison. I have both, and DMR is much more complicated of the two in terms of programming and twice as efficient in spectrum use. DMR radios also are more expensive, but the gap has closed with some of the newer DMR offerings.

 

[teufler]

thank you all and to all a good night!! Back to the cards game.

 

[Project25_MASTR]

It may be of note DMR radios with the AMBE3000 chip tend to have inital audio issues as well. You see this with most of the cheaper DMR radios. The more expensive radios tend to use a AMBE+2 chip.

 

[slicerwizard]

DMR versus dPMR comparison

The link above gives you a good comparison.

A highly biased comparison.

I have both, and DMR is much more complicated of the two in terms of programming and twice as efficient in spectrum use.

What? How do you figure DMR is twice as efficient in spectrum use?

 

[FR3500]

The main difference for me is up to now i can hear all DMR coms using DSD

as for dPMR isn't available

Only way to hear it would be AR-DV1 but expensive ...

 

[johnls7424]

It may be of note DMR radios with the AMBE3000 chip tend to have inital audio issues as well. You see this with most of the cheaper DMR radios. The more expensive radios tend to use a AMBE+2 chip.

Even the Tytera MD-380 has a AMBE+2 vocoder anymore

 

[paulears]

I've been reading all this myself recently, and am having trouble with the differences because the dumbing down of the technicals has actually confused me more.

Nobody seems to have yet produced a definitive list with compatibility between makes, which is amazing. The basic differences between them seem to be the time division slots on one vs the frequency division on the other. They both fit into the same width channel. The Tait white paper is not really a white paper if you expect technical details, because it's presented for easy basic level understanding. Using the example of a dpmr channel needing two transmitters is a poor one, because clearly it doesn't, just one transmitter capable of producing the two channels, in a similar way to how an analogue radio transmitter deals with stereo by having two parallel streams. I read that you cannot send digital radio data through a repeater, for example, but does this apply to dmr as well as dpmr? I can understand how the two parallel streams wouldn't work with the analogue repeater, but maybe it could with a dmr td system? No idea.

Worse still are the other variables with codecs and vocoders. Are these compatible or not. I've only found one link that lists other radios with compatible facilities, like the kirisuns. Everyone seems to be buying these things then discovering X radio doesn't work with y! The Chinese specs are terrible, they give no real technical data, so I expected the dealers to do it, but they don't, keeping the info secret. If you buy dmr then it really should work with any other dmr, otherwise it's not a proper standard, same with dpmr. You read all the stuff and view simply awful YouTube reviews that don't review anything useful apart from opening boxes.


Has anyone seen a proper comparison chart? Maybe we should start a topic where people who have tried two radios of different brands could detail success or failure and we could build up something useful. It's really silly that this doesn't seem to exist.

 

[teufler]

I guess you buy the one that fits the repeater that you are going to talk on. Then another one for another repeater.

 

[paulears]

I've started the research, and already discovered a couple of DPMR radios that won't talk to each other, but finding people with different makes that work seems to be a tough one. So many reviews and comments are really rubbish with no technical knowledge so difficult to assess if incompatibility is down to the hardware and software, or people just not understanding the programming parameters.

I've found a couple of real idiots on Youtube who clearly have no real idea and are advising people really badly - getting DMR and DPMR mixed up, and one video clearly showing the radio is on an analogue channel, and they talk about the super digital audio quality. Another talks about the digital reverberation designed to help it be understood and identified, when all they are hearing is the latency of the two D/A processes feeding back slightly, which have that weird 'hollow' delayed sound (latency) - that you do not hear when using the radio without another local to it!

 

[hitechRadio]

A highly biased comparison.


What? How do you figure DMR is twice as efficient in spectrum use?

I agree, biased for sure.

With out doing much research. At first glance it seems to me IMO, DPMR is nothing more than NXDN in a way. Just CAI is different, and as such makes them incompatible..

A VERY simplistic view of course.


NXDN=NXDN is an "open proprietary protocol"
dPMR= dPMR is an ETSI Standard

 

[paulears]

It isn't - the data is just streamed differently. One thick vs two thin, in it's most simplistic format.

I was going with DPMR, not DMR, but it turns out my order for the Zastones got cancelled as their now discontinued, so now I'm thinking again. I'm viewing the whole thing like the battle for VHS or Betamax - realistically, there really wasn't anything in it.

 

[hitechRadio]

It isn't - the data is just streamed differently. One thick vs two thin, in it's most simplistic format.

Do you mean in my comparison of dPMR to NXDN?


DMR= TDMA

dPMR= FDMA
NXDN=FDMA

NXDN is based on dPMR but is incompatible with it.

As to the OP of this topic dPMR and DMR , the difference is TDMA vs. FDMA.


Without considering bandwidth:

TDMA is to P25 Phase2 and DMR
FDMA is to P25 Phase1, NXDN and dPMR

 

[paulears]

yes - to all of that. I suppose you could also describe it as serial vs parallel at the basic level. I do agree that the critical difference is the time slot system which is the real difference that people can understand.

What is causing me real problems are the subtle differences, and where specs sometimes say "based on the XYZ protocol", yet give no information on compatibility. I hate it when you see 'compatible with motorola' but then you read of people who cannot make them work. Sometimes this seems to simply be programming rather than absolute incompatibility.

As a buyer, it's causing me plenty of grief in selection.

 

[n9upc]

I have known dPMR and DMR to be broken down via technology and maker type: DMR is of the likes of Mototrbo/Hytera and dPMR is of Nxdn/iDas. This does not mean these are the only ones but they are the bigger more known in the US where I live.

Here is the break down for technical reasons:

DMR - Digital Mobile Radio - Uses TDMA (Time Division) digital technology in which a 12.5 Khz channel is actually divided into a series of time slots (known as time slot 1 and 2) that are equally spaced in the 12.5 khz spacing. [NOTE: It is argued that this achieves 6.25 khz channel spacing even though using 12.5 khz because a time slot uses 6.25 of the 12.5 spacing].

dPMR - Digital Private Mobile Radio) - Uses FDMA (Freq Division) digital technology in which this can breakdown a 12.5 Khz channel spacing into two 6.25 Khz channel spacing. It does NOT use time slots like TDMA as the frequency is just sliced into equal paths within a 12.5 Khz channel.

Hope this helps and does not hinder.

 

[Voyager]

FDMA is to P25 Phase1

P25 Phase I is a single-user modulation. It is not FDMA (or any MA at all).

 

[n9upc]

P25 Phase I is a single-user modulation. It is not FDMA (or any MA at all).

Sorry P25 Phase 1 is FDMA feel free to google search and see white papers and reports from all the manufacturers of P25 Phase 1

The P25 Common Air Interface (CAI) on P25 Phase 1 uses a technology known as Frequency Division Multiple Access (FDMA), where the channels are divided according to frequency. The channel bandwidths for voice and traffic channels are 12.5kHz. It is backwards compatible with analog.

 

[Project25_MASTR]

Sorry P25 Phase 1 is FDMA feel free to google search and see white papers and reports from all the manufacturers of P25 Phase 1

It is actually C4FM, a subset of FDMA. FDMA (see why some of us are complaing about Yaesu building a new C4FM protocol that can't play with an existing standard).

 

[Project25_MASTR]

I have known dPMR and DMR to be broken down via technology and maker type: DMR is of the likes of Mototrbo/Hytera and dPMR is of Nxdn/iDas. This does not mean these are the only ones but they are the bigger more known in the US where I live.

Here is the break down for technical reasons:

DMR - Digital Mobile Radio - Uses TDMA (Time Division) digital technology in which a 12.5 Khz channel is actually divided into a series of time slots (known as time slot 1 and 2) that are equally spaced in the 12.5 khz spacing. [NOTE: It is argued that this achieves 6.25 khz channel spacing even though using 12.5 khz because a time slot uses 6.25 of the 12.5 spacing].

dPMR - Digital Private Mobile Radio) - Uses FDMA (Freq Division) digital technology in which this can breakdown a 12.5 Khz channel spacing into two 6.25 Khz channel spacing. It does NOT use time slots like TDMA as the frequency is just sliced into equal paths within a 12.5 Khz channel.

Hope this helps and does not hinder.

Stated that way is a little confusing. DMR (TRBO) uses a 12.5 kHz channel (2.5 kHz dev), period. Due to the time division, you get 2 channels in that 12.5 kHz step so it is equivalent in terms of occupied band width to running twin 6.25 kHz channels (at 1.25 kHz dev).

NXDN (NextEdge, iDAS) only gives a single channel. It can be either 12.5 kHz wide or 6.25 kHz wide. So to get two channels in 6.25 kHz would require two repeaters.

Thus the debate between NXDN and DMR (in the US). NXDN subscribers are cheaper (roughly 40% the cost of DMR subscribers). However, the 6.25 kHz thing means it is much more expensive to get two channels in a 12.5 kHz space requiring either 2 times the number of sites or a multicoupler (couple thousand dollars right there) at each site to get the same system capacity as DMR. NXDN favors the consumers, DMR favors the system owners due to same capacity on half the hardware (minus 1 time slot for control on a trunk system).