VFDs and DMR

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wbswetnam

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What's with volunteer fire departments switching to DMR? In the last few days, Tuckerman VFD (in Jackson County) and Pleasent Plains VFD (in Independence County) appear to have switched to DMR instead of NFM. All comms for both departments are now the runaway diesel engine sound. DMR keeps taking over more and more in Arkansas. I hope that someday a DMR capable scanner comes on the market.
 

milf

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If you have like an PRO-106, or one of the Uniden Tap to PC/IF enabled type scanners, or an tapped older scanner, you can run DMR Decode to get the usage data, and DSD+ or original DSD to monitor the audio currently.
 

wbswetnam

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My RS Pro-96 has a port on the side that says PC/IF, that's what you're talking about I think.(?) So I can run an audio cable from it to the mic input on the PC while it is running DMR Decode? Do I need some kind of matching filter in between?
 

chudson584

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DMR and NFM are not unrelated. DMR is a type of transmission and NFM is a mode. Narrow FM means less spacing in frequency in khz, 6.25, 12, etc. FCC mandated a switch to NFM because it opens up more room on the frequency spectrum because there is hardly any left. DMR, if its on public safety freqs, will be transmitting in NFM if they followed the FCC mandate. DMR is a cheaper alternative to P25 but it doesn't allow for interop or is the industry standard. DMR does allow more talkpaths and such, but both have there pro and cons. DMR is intended for commercial use i.e casinos, schools, business, etc.
 

wbswetnam

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FCC mandated a switch to NFM because it opens up more room on the frequency spectrum because there is hardly any left.
Hardly any spectrum left? VHF-low band is now all but abandoned in most parts of the country, it seems. I know of only one LE agency in Arkansas which still uses VHF-low band, and that is Boone County. They use 37.160 MHz for simulcast of selected communications in the clear for the public.
 
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03msc

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Hardly any spectrum left? VHF-low band is now all but abandoned in most parts of the country, it seems. I know of only one LE agency in Arkansas which still uses VHF-low band, and that is Boone County. They use 37.160 MHz for simulcast of selected communications in the clear for the public.
He was correct in saying that was the main reason for the switch to NFM as many of the bands were getting too crowded. You are correct about low being a lot more open now, as well, however.
 

kayn1n32008

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... DMR, if its on public safety freqs, will be transmitting in NFM if they followed the FCC mandate.
Actually if using DMR the transmitting radio occupies a 12.5KHz channel, it does not transmit NFM.

DMR is a cheaper alternative to P25...
Cheaper yes, and has similar features. Subscribers are less than half the price, infrastructure is significantly cheaper as well.

...but it doesn't allow for interop...
You are gonna have to explain is. How is using analogue NFM not interop.

Interoperability is NOT a technology, it is a state of mind. People have to WANT to talk to each other, the infrastructure is only the conduit.

If the county of Big Sky(made up place) has a county wide DMR trunk system, that ALL police, sheriff, fire, ems, dpw, emo, peace officers are on, with common talk groups in all radios every one can talk to each other. THAT is interoperability. Throw in band specific analogue NFM. Interop frequencies and they can talk to other that are not users on their system.

EVERY DMR radio I have looked(except the SL-7550, which is targeted at the hospitality industry) at WILL operate in simple analogue FM.

No matter what the flavour of subscribers be it P25, NXDN, or Opensky, they all can be used conventional analogue, That IS interop. All digital technology does is make interop more difficult, not easier. And for people on different bands, gateways solve that problem.

...DMR does allow more talkpaths and such, but both have there pro and cons. DMR is intended for commercial use i.e casinos, schools, business, etc.

Motorola has targeted DMR at public safety, they bill it as a less expensive option to P25.

Having used DMR in an industrial setting I am impressed with its performance, and audio quality. It works well, when the system is engineered correctly, by competent technicians. The company that has the system I use, wentto a UHF MotoTRBO trunk system from conventional VHF analogue. Having used both, I actually like the TRBO better simply because the audio is not all over the place, and the volume has, more or less, become a set and forget, unlike the VHF system that I was constantly adjusting.

Thanks to some slick marketing by certain large P 25 infrastructure providers, people have started to believe 'if it ain't P25 it is not interop' and nothing is farther from the truth.


The fact that a scanner can not listen has no bearing on how I feel about the technology. I simply want a system that works.



Sent from my iPad using Tapatalk
 

wbswetnam

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My RS Pro-96 has a port on the side that says PC/IF, that's what you're talking about I think.(?) So I can run an audio cable from it to the mic input on the PC while it is running DMR Decode? Do I need some kind of matching filter in between?
Can anyone answer my question?
 

milf

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The output from an 96 via the PC/IF port is NOT adequate for using DSD/Unitrunker/T-88 etc... It wasn't set up to properly do this and does not feed audio from the Discriminator Tap Point correctly that method. You can tap an 96 super easy, almost as easy the 92's. The 106's however, and several other newer gen scanners do provide Discriminator Audio vias the PC'IF ports, and some even have an specific discriminator audio port on them. The data that is put out on the 96's PC/IF port however works perfectly with Pro96Com, and indeed that software was specifically designed to use the data from the 96/2096's...
 

03msc

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Not saying they aren't in the process of changing or whatever but I've heard P Plains still on their VHF conventional today several times.
 

wbswetnam

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Not saying they aren't in the process of changing or whatever but I've heard P Plains still on their VHF conventional today several times.
Me too, but yesterday I heard the diesel engine sound on their channel on two different radios. Maybe it was just testing. Also today I heard Tuckerman VFD (in Jackson County) in the clear. But I was able to find their PL tone so I reported it to RR so at least we can hear the regular FM transmissions when they have them.
 

milf

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Multiple agencies in IndCo and the surrounding area are joining the ever growing list of DMR users in AR. They will multi cast during testing, and then may even simulcast in both analog and DMR until everyone has the DMR radios etc... Then most likely, they may keep an anlog set up for county dispatching, and interop... While primary ops will be DMR. This seems to be how most are doing it. Though Clark County seems to be still fully simulcasting DMR and Analog. Go figure!
 

03msc

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Multiple agencies in IndCo and the surrounding area are joining the ever growing list of DMR users in AR. They will multi cast during testing, and then may even simulcast in both analog and DMR until everyone has the DMR radios etc... Then most likely, they may keep an anlog set up for county dispatching, and interop... While primary ops will be DMR. This seems to be how most are doing it. Though Clark County seems to be still fully simulcasting DMR and Analog. Go figure!
milf always has the inside line so I expect this really will happen. Of course it's kind of inevitable, I guess, for them to switch over. Got any info on who all is switching, when to expect it, etc.? Or is it everyone?

Not happy about this myself but if there's a way to monitor it then I guess I'll be doing some research on that soon. Guess that means no mobile monitoring, though...
 

milf

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I don't know if every VFD is going to switch. But it is the current TDMA Narrowband Digital solution for conventional radio, and is cheap relatively speaking. It offers the best bang for buck for efficient spectrum management until they can come up with an P25 Phase II standard for conventional. You get much more usage, and control per frequency. Using just Narrowband FM opens up more feqs in band, yes, but you still can only have one user on a freq with analog, NXDN digital, and even P25 conventional currently. With DMR which is TDMA (currently 2 slot, soon 4 slot, then 6 slot) you can have 2 users at the same time. For an smaller rural agency this has big time appeal. Now I can be dispatching and having 1 incident on Slot 1, and another incident on Slot 2.... Or have Fire Primary on 1, EMS/First Responders etc Slot 2.... For a countywide agency, its even more appealing. Lets take an county that is using analog NFM and say the SO needs to do dispatch for itself, North, South, and has lets say a smaller town North, and South it dispatches PD for. This means at least 2 repeaters, that you have to share time on and be stepping on each other pretty constantly even if you are using different tones for SO and PD's. Now lets take it to TDMA Digital: 2 repeaters, but now, efficient usage is going on simultaneously and no one is "preempting" or "walking on" anyone else. Not to mention there is advanced digital encryption at the push of a button for security.
 

milf

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Speaking of: Craighead County Fire Services.... New Lic for VHF Conventional....
WQTJ962
Jonesboro
155.6175 Repeater Out
151.3175 Repeater In
Black Oak
154.2200 Repeater Out
151.1525 Repeater In

Emissions-
11K2F3E Narrowband FM
7K60FXE TDMA 2 Slot DMR

So possibility of them going DMR for conventional in addition to AWIN use.

And New Lic for Pineville FD in Izzard County

WQTJ906

154.3250 Repeater Out
158.9850 Repeater In

Emissions-
11K2F3E Narrowband FM
11K2F1D Narrowband FM Data (Paging)
Looks like they will be Analog NFM for the VHF Conventional.
 

03msc

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I don't know if every VFD is going to switch. But it is the current TDMA Narrowband Digital solution for conventional radio, and is cheap relatively speaking. It offers the best bang for buck for efficient spectrum management until they can come up with an P25 Phase II standard for conventional. You get much more usage, and control per frequency. Using just Narrowband FM opens up more feqs in band, yes, but you still can only have one user on a freq with analog, NXDN digital, and even P25 conventional currently. With DMR which is TDMA (currently 2 slot, soon 4 slot, then 6 slot) you can have 2 users at the same time. For an smaller rural agency this has big time appeal. Now I can be dispatching and having 1 incident on Slot 1, and another incident on Slot 2.... Or have Fire Primary on 1, EMS/First Responders etc Slot 2.... For a countywide agency, its even more appealing. Lets take an county that is using analog NFM and say the SO needs to do dispatch for itself, North, South, and has lets say a smaller town North, and South it dispatches PD for. This means at least 2 repeaters, that you have to share time on and be stepping on each other pretty constantly even if you are using different tones for SO and PD's. Now lets take it to TDMA Digital: 2 repeaters, but now, efficient usage is going on simultaneously and no one is "preempting" or "walking on" anyone else. Not to mention there is advanced digital encryption at the push of a button for security.
Yeah, sounds like a good deal...obviously the only reason I'm against it is because I can't monitor it easily. But if it IS monitorable through these methods then that'll be good.

As you can see in my signature, I have a Pro-106 so hopefully the PC/IF will let me easily listen. At least I hope it's fairly easy. I'm computer savvy I just don't want to get a headache trying to figure out some complicated program... :roll:

Hey, it's Sunday afternoon and I'm being lazy today...
 

03msc

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At the risk of sounding completely stupid I'm going to ask this anyway...could a person purchase a DMR radio to monitor these frequencies after they convert? Or is it similar to P25 and AWIN where a wrong RID would/could result in a bricked/killed radio?
 

n5ims

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Can anyone answer my question?
No, PC/IF is the programming interface, not the Discriminator Tap connection. Actually there isn't an external Discriminator Tap connection on an unmodified Pro-96. It's pretty easy to do though if you can follow some simple directions. The tap is labeled TP4 and fairly easy to get to. Just connect to that (it'll need some very simply soldering, but nothing a beginner can't handle after 15 minutes of practice or so.

This link shows you the tap point inside the scanner. Pro 93/95/96 Tap - The RadioReference Wiki

More info here Discriminator output - The RadioReference Wiki

Also this old thread on this topic has some good info for you as well. http://forums.radioreference.com/radio-shack-scanners/221-pro-96-discriminator-tap.html
 
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