Digital Radios

[adamnfd202]

Im looking for a system for a FD where i can take our current VHF freq pair and split into two talkgroups. Like the Mototrbo. Are there any other systems like the MotoTrbo?

[DaveNF2G]

Do you want the two groups to be used simultaneously?

[texasemt13]

The P25 protocol can handle multiple talkgroups on a repeater pair. It might make it a little tougher on a dispatcher (to follow the correct conversation), but mobiles/portables shouldn't be able to tell a difference.

[RKG]

You might want to check NFPA 1221 before pushing an FD into digital voice.

[Baylink]

No, the 1999 edition is apparently not new enough.

Link removed.

I'm sorry: I took out the thank you to David; 1221 is clearly something I ought to read.

[JRayfield]

In order to have two simultaneous conversations on one RF repeater pair, you will have to use TDMA technology. MOTOTRBO offers that technology, using the DMR standard, as does equipment from Hytera. Vertex is supposed to have DMR-based equipment by the end of this year, and Tait is advertising that they will also have DMR-based equipment (not sure of the time frame for Tait equipment).

Just a quick comment on the use of digital voice in the fire service....

Not all digital is created equal. MOTOTRBO works VERY well in high-noise environments, where P25 digital has been useless. I've personally done some testing myself and have been amazed at how well it works. You can hear these tests for yourself at: - MotoTRBO Sound Tests : Motorola 2-Way Radios - Springfield, MO, Implementing New and Emerging Technology. A local fire department also tested MOTOTRBO. They found that it worked better than analog in high-background-noise situations in all cases except when using SCBA equipment. In those cases, it was comparable to using analog (no better, but not worse).

John Rayfield, Jr. - CETma

[Baylink]

And a further apology to RKG, who's the person who actually pointed out 1221; I am *not* having a good week, am I? :-)

[DaveNF2G]

Another caveat - MOTOTRBO might not be eligible for some forms of government grants because it is not P25 compliant.

[rdale]

I've had a lot of government radio grants come across my table, and none required P25. We just picked up roughly a million in my region and $0.00 is going towards P25 work.

[w9jlm]

Originally Posted by adamnfd202

Im looking for a system for a FD where i can take our current VHF freq pair and split into two talkgroups. Like the Mototrbo. Are there any other systems like the MotoTrbo?

Hytera has a great product. Harris just announced they will also sell a product (which is being made by Hyterea and being re-branded)

[RKG]

1221 involves issues beyond the digital frame sync issue and the background noise issue. For instance, on the fireground, it is essential that units in a building be able to transmit simplex to companies outside in the event of a mayday. Trunking doesn't permit that, and neither does MotoTRBO.

[JRayfield]

DMR (MOTOTRBO) provides for simplex operation.

John Rayfield, Jr. CETma

Originally Posted by RKG

1221 involves issues beyond the digital frame sync issue and the background noise issue. For instance, on the fireground, it is essential that units in a building be able to transmit simplex to companies outside in the event of a mayday. Trunking doesn't permit that, and neither does MotoTRBO.

[70cutlass442]

Originally Posted by adamnfd202

Im looking for a system for a FD where i can take our current VHF freq pair and split into two talkgroups. Like the Mototrbo. Are there any other systems like the MotoTrbo?

Before you spend a ton of taxpayer money, and put your mens lives on the line. Explore other options. Im a FF/EMT as well and know first hand how bad just about anything digital is in the fire service. No mater what those slick salesmen have to say...

[JRayfield]

A nearby fire department just recently did some testing with some MOTOTRBO portables. They wanted to see how the background noise suppression would work in high noise environments. They tested them near a generator as well as near saws. The radios worked great. The fire department personnel were very impressed.

This is the 2nd fire department in this area that I know of personally that has tested MOTOTRBO equipment in high-background-noise environments and found it to work extremely well.

The police department in this same town tested the same system for range. With their analog system, they've counted about 12 'dead spots' in the town. On the MOTOTRBO system, they had 1 'dead spot'. They've also had trouble with coverage in a nearby town, from the same repeater site. All 'dead spots' were gone, except for 1, which was VERY low in elevation.

I was given this information directly by the police chief, so it's 'factual'.

Not all digital is created equal. Just because P25 digital systems have trouble in some situations does not mean that MOTOTRBO suffers from the same problems.

John Rayfield, Jr. CETma

Originally Posted by 70cutlass442

Before you spend a ton of taxpayer money, and put your mens lives on the line. Explore other options. Im a FF/EMT as well and know first hand how bad just about anything digital is in the fire service. No mater what those slick salesmen have to say...

[RKG]

Originally Posted by JRayfield

DMR (MOTOTRBO) provides for simplex operation.

John Rayfield, Jr. CETma

It is true that one can configure a MotoTRBO system to work on a simplex channel, at least for cutover purposes. What you can't do is use "direct" to hit people on a nearby sidewalk who are listening on the "system" channel, which is the capacity that jakes at a fireground need to have.

[JRayfield]

I see what you mean.

Actually, MOTOTRBO does operate this way, if the system is a conventional repeater system. A radio on a repeater can still hear a radio that is in 'talkaround mode', on the same frequency as the repeater output. It's operates exactly the same as an analog system.

With trunking, there is no 'talkaround' mode like what you're describing. Of course, that didn't exist in LTR trunking either, or Smartnet/Smartzone. So it's not an issue with "digital", it's the fact that in a trunking system, a transmission through the system may be on one of a number of frequencies, whereas the portable on 'simplex' is only going to be on one frequency. And if the two don't match, they aren't going to hear each other. In any trunking system, radios must 'scan' between the trunking system and 'conventional simplex' mode.

John Rayfield, Jr. CETma

Originally Posted by RKG

It is true that one can configure a MotoTRBO system to work on a simplex channel, at least for cutover purposes. What you can't do is use "direct" to hit people on a nearby sidewalk who are listening on the "system" channel, which is the capacity that jakes at a fireground need to have.

[w9jlm]

Originally Posted by RKG

1221 involves issues beyond the digital frame sync issue and the background noise issue. For instance, on the fireground, it is essential that units in a building be able to transmit simplex to companies outside in the event of a mayday. Trunking doesn't permit that, and neither does MotoTRBO.

How do you figure this? The Hytera and MotoTrbo radios are mixed mode. You can easily change a channel for innerop with old analog users. Maybe i dont understand what you are trying to say here. They also have talkaround for simplex.

[w9jlm]

Originally Posted by RKG

It is true that one can configure a MotoTRBO system to work on a simplex channel, at least for cutover purposes. What you can't do is use "direct" to hit people on a nearby sidewalk who are listening on the "system" channel, which is the capacity that jakes at a fireground need to have.

Yes you can. If user "A" and user "B" are on a repeater network, and then get to a fire scene and "A" is incedent command, and stays on repeater to talk to dispatch. "B' goes into structure fire and goes to talk around for "firegrounds". Now, "A" can talk to the main dispatcher and not miss a call from "B", inside. Also, "B" can hear "A".

Another option is to have "A" stay on the repeater channel (ch1), and then program a second channel (ch2) in "B's" radio for a select call or group call on the repeater output. This essentially makes it easier to change a channel now than push a button with gloves on. Then, you simply program the ch1 with the talkgroups of both the "system (duplex) and firegrounds (simplex)" with revert. This way the radio Automatically switches to the last hear talkgroups form of comm (repeater or direct).

[w9jlm]

Originally Posted by 70cutlass442

Before you spend a ton of taxpayer money, and put your mens lives on the line. Explore other options. Im a FF/EMT as well and know first hand how bad just about anything digital is in the fire service. No mater what those slick salesmen have to say...

With narrowbanding, the noise threshold is very bad. Once the signal into a repeater or from repeater to field unit gets weaker, the noise on the signal obviously increases. However, with a narrowband signal, it increases much faster, with the reduced bandwidth. I have personally seen coverage on an conventional analog system be cut in half due to narrowbanding. We have converted such systems over to DMR Hytera, and actually seen coverage improve by 15-20% over a conventional wideband systems range. So, to say that DMR has no place in FF or EMT, is incorrect. Not to mention the digital mandown, gps, remote monitor, etc options that are available with DMR. Most FF's i know would rather have their collegues hear them clearly, and be able to find them when they are in need of help, than to sit and listen to narrowband analog hash and pray to God someone finds them.

[JRayfield]

Originally Posted by 70cutlass442

Before you spend a ton of taxpayer money, and put your mens lives on the line. Explore other options. Im a FF/EMT as well and know first hand how bad just about anything digital is in the fire service. No mater what those slick salesmen have to say...

So, have you personally used MOTOTRBO and tested it in weak-signal and high-background-noise conditions?

John Rayfield, Jr. CETma