I have been trying to find differences between P25 and DMR, why do public safety agencies tend to use P25 more? From my experience they both sound the same, and do the same, plus DMR is cheaper..
DMR vs P25
- Thread starter thecanadiangod
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kayn1n32008
ØÆSØ Say it, say 'ENCRYPTION'
Phase 2 and DMR may sound similar, P25 phase 1 and DMR definitely do not sound alike.
P25 was specifically designed for public safety. DMR was not. P25 was specifically designed to use encryption, DMR it was an after thought.
Yes DMR is cheaper, bit they do not do things the same
P25 was specifically designed for public safety. DMR was not. P25 was specifically designed to use encryption, DMR it was an after thought.
Yes DMR is cheaper, bit they do not do things the same
RFI-EMI-GUY
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DMR is newer and in some respects, a better technology if interoperability with P25 is not essential. However you can buy radios that do both, but not from Motorola.
Or Harris or Icom or BK or….
How is P25 better with Interop than DMR? Can you not patch two DMR talk groups?
nd5y
Member
In the US P25 is the only mode allowed on the 700 MHz national interoprability channels.
I don't know if it's still in effect but for a long time there were government grants available for buying radios and they had to be capable of P25.
Which brands offer this? Tait maybe?
Kenwood NX-5x00 series Radios.
NX-5200 NX-5700 VHF
NX-5300 NX-5800 UHF
NX-5400 NX-5900 700/800
NX-5200 NX-5700 VHF
NX-5300 NX-5800 UHF
NX-5400 NX-5900 700/800
RFI-EMI-GUY
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RFI-EMI-GUY
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Its only better for Public Safety interoperability because of the proliferation of P25. After demodulation to analog, you can patch two ham sandwiches if you want. And EFJ has radios that do both DMR and P25 so there is always that.
kayn1n32008
ØÆSØ Say it, say 'ENCRYPTION'
Patching can be done, via audio bridge in DMR, where as P25, at least with Harris and Harris conoles, more efficient.
The other draw back to DMR is there is a loss of voice quality when using ARC4 or AES encryption. You don't lose audio quality when encrypting P25.
kayn1n32008
ØÆSØ Say it, say 'ENCRYPTION'
Tait and EFJohnson both ha e multiband radios that support P25 Phase 1&2 and DMR Tier 2, with Tier 3 on the road map.
100% There are those who say it is barely noticeable, that is -not- true
I haven't noticed any audio quality degradation (I mean, DMR already sounds like a** to begin with). However using AES on DMR absolutely reduces your usable range. It only applies in deep fringe areas, but it can make the difference in those situations.
Project25_MASTR
Millennial Graying OBT Guy
There are a multitude of reasons why one format is better than another...but here's some of the points I've gathered over the years.
Subscribers:
Subscribers:
- P25 subscribers tend to be built to a much heavier duty specification compared to many DMR subscribers.
- Until this last year, there wasn't such a thing as a multi-band DMR that would function in VHF and 800 MHz.
- Until Kenwood added DMR to the NX5000, multi-ID DMR radios simply weren't a thing. Thus it took a lot of coordination to coordinate one ID that could be potentially used across multiple DMR systems...P25 hasn't had this issue since the P16 with CAI voice hybrid systems were still being sold (i.e 20 years now) as unique ID's per system is pretty common (unless you are somewhere like Texas where we have statewide ID standards).
- Grants often dictate P25 capability (again, unless working with Kenwood branded radios P25 and DMR weren't in the same radio).
- P25 was originally based off of the IMBE vocoder which has since been replaced with AMBE 2 but there has always been focus on backwards compatibility with the previous generation (i.e. Phase 2 being backwards compatible with Phase 1, Phase 1 being backwards compatible with analog).
- DMR has a Inter-System interface called AIS where P25's is called ISSI. AIS and ISSI can be used to interconnect different systems, even manufactured by different vendors.
- P25 has a standard for integrating consoles to any vendor's system called CSSI. DMR has no equivalent.
- P25 has a standard command/control IP protocol for repeaters called DFSI. DMR has no equivalent. DFSI is used by several manufacturers to control repeaters for both conventional and trunking applications (so you can literally have one P25 trunking controller at a site interfaced to multiple repeaters from various vendors). DFSI can also be used in conventional applications to with a console to make a repeater/base function as a high powered, remote transceiver.
A Fire Department in West Tennessee near me got a Government Grant for Radio Upgrades.
MTS2000des
5B2_BEE00 Czar
When? I was on the board that put together a new system in middle Georgia last year, and we couldn’t find grants for it anywhere.
This is a completely new system, going from a single analog transmitter site, to multiple site simulcast DMR. Had there been grants available that packed a punch, we would have went P25
Project25_MASTR
Millennial Graying OBT Guy
We have state funded infrastructure grants that will dictate P25 capability for voice.
