Anyone out there using......

[BSFD9302]

Anyone out there using the Motorola Astro P25 VHF Digital radio system? Our county is getting ready to switch and am looking for some info from people with experience with them. Is there is quirks with using radios with voice amps? How far away to hold radio if it is different from using a Analog radio? Any information like that would be helpful instead of finding out on the first run we use them on. There will be testing but most likely will not be testing in a real world situation.

Note:

I am not the project manager of the change, just one of the guys in the county wondering about how the system works.

[tree68]

Any experience with trunked systems?

Wait for the beep, then talk.

Know that you can't just key up over anybody - your radio won't let you.

Make sure you have a simplex fireground channel. If you can't hit the repeater, you can't talk to anybody - at least with simplex all you have to hit is another radio on the scene.

Know that you can have lots of talk groups. Different areas/functions can use them instead of tying up dispatch or what may be your only fireground channel.

There were problems with background noise (saws, especially) with some vocoders - know how your system works. That's getting sorted out.

Hopefully you'll have some overlap between the systems. Once you get the new radios in hand - play with them. All over your district. Because it's a repeated system, you can check for coverage without bothering dispatch. Just go to a fireground talkgroup and talk to each other.

If you're not used to a trunked system, there will be some adjustment. In the end you'll wonder why they waited so long.

That discounts any engineering shortfalls the system may or may not have. You'll have to sort them out locally.

[BSFD9302]

Any experience with trunked systems?

Wait for the beep, then talk.

Know that you can't just key up over anybody - your radio won't let you.

Make sure you have a simplex fireground channel. If you can't hit the repeater, you can't talk to anybody - at least with simplex all you have to hit is another radio on the scene.

Know that you can have lots of talk groups. Different areas/functions can use them instead of tying up dispatch or what may be your only fireground channel.

There were problems with background noise (saws, especially) with some vocoders - know how your system works. That's getting sorted out.

Hopefully you'll have some overlap between the systems. Once you get the new radios in hand - play with them. All over your district. Because it's a repeated system, you can check for coverage without bothering dispatch. Just go to a fireground talkgroup and talk to each other.

If you're not used to a trunked system, there will be some adjustment. In the end you'll wonder why they waited so long.

That discounts any engineering shortfalls the system may or may not have. You'll have to sort them out locally.

All of that we have on our current UHF system, except the talk groups. We had some meetings over the system and our dispatch has been testing it all over the county. The initial results appear that the coverage is really good on the VHF digital system. Is there any quirks with a digital systems that the analog VHF system does not have that can affect communications?

[tree68]

The 'digital cliff' can be a factor, or not. Essentially it means that when you hit the end of sufficient signal, and get beyond what error correcting can fix, your communications drops to zero, as opposed to an analog system, where things peter out but you can often still sort out what is being said.

That all depends on where that occurs. If it's outside your normal response areas, it won't be an issue.

[voyager9]

All of that we have on our current UHF system, except the talk groups. We had some meetings over the system and our dispatch has been testing it all over the county. The initial results appear that the coverage is really good on the VHF digital system. Is there any quirks with a digital systems that the analog VHF system does not have that can affect communications?

We've been using a Digital Trunked system to handle our Response communications (apparatus, Central communications..etc). Our fireground communications remain analog.

I wouldn't use a trunking system for your fireground communications. We found that being inside buildings drastically reduced or eliminated our ability to hit the towers with the portables. As mentioned above, if your radio can't hit the tower you are not going to talk to ANYONE.. even another radio 2 feet away. With Trunked everything is routed through the central system. No Comms to that system, no comms to anyone.

Check out section 3.4 of our county Radio Manual for more information.

[voyager9]

That all depends on where that occurs. If it's outside your normal response areas, it won't be an issue.

We were more concerned with having it occur when we needed it most.. like in a basement after a floor collapse. I'd much rather fireground be limited-range LOS then county-wide but dependent on hitting the tower from within a building.

[tree68]

We were more concerned with having it occur when we needed it most.. like in a basement after a floor collapse. I'd much rather fireground be limited-range LOS then county-wide but dependent on hitting the tower from within a building.

Which is why I suggested a simplex channel (or several, for that matter). Analog is a good thing too, unless your vendor has gotten around the noise issue with their vocoder.

Some jurisdictions have expressed concern about folks who are in simplex mode being 'off the net,' and thus unable to declare an emergency with their radio. There are ways around that. Talk to your vendor.

As can be seen from Voyager's link, a really great thing about trunked systems is the ability to create and use talkgroups. When implementing a system, be prepared to think outside the box. Stuff like a separate talkgroup for each department/station, for special teams, even for management, are not beyond possibility. One county I know of set aside a couple of "training" talkgroups so departments could conduct multi-agency exercises without tying up the regular tactical channels.

The system I set up has three "special event" talkgroups that are included in every radio - from the fire chief to the dog catcher to the street sweeper. That allows for a common channel for all agencies operating at a special event.

I also included in all administrative (non-public safety) a "9-1-1" talkgroup which is monitored by the 9-1-1 dispatchers. It can be used to report an incident directly.

V's link shows an interesting method of assigning working talkgroups. A county near me assigns a fireground (working) talkgroup on dispatch. They are not a tremendously busy county, though. I've never heard them go above "fireground 4." That would have been three concurrent incidents, as they stayed with the familiar and the first fireground channel is '2'.

[voyager9]

Some jurisdictions have expressed concern about folks who are in simplex mode being 'off the net,' and thus unable to declare an emergency with their radio. There are ways around that. Talk to your vendor.

That is one of the drawbacks to our setup. Since the fireground chatter uses the analog channels that have a limited (2-mile'ish) range they are not monitored by Central, and cannot take advantage of the trunking system's emergency features (mainly priority).

V's link shows an interesting method of assigning working talkgroups. A county near me assigns a fireground (working) talkgroup on dispatch. They are not a tremendously busy county, though. I've never heard them go above "fireground 4." That would have been three concurrent incidents, as they stayed with the familiar and the first fireground channel is '2'.

Our county is broken up by geographic region (North, North-west, North-East, East..etc). Each region gets a bank of response talk groups (R1, R2, R3..etc). By default everyone in the region uses the first group (R1) but communications are moved to R2.. R3 when major incidents occur. Note: The major incident stays where they are, and all other incidents get moved.. future incidents are told to use the new group on dispatch. On the analog side there are 6 Ops channels but everyone defaults to Ops1. The only time Ops2 is used is when two incidents are close together or when a single incident requires additional channels (staging, pipeline..etc).

While a lot can be done with talkgroups, the KISS principle still applies. You can do an awful lot that sounds good on paper but get wrapped around the axle out in the field.

[voyager9]

Some jurisdictions have expressed concern about folks who are in simplex mode being 'off the net,' and thus unable to declare an emergency with their radio. There are ways around that. Talk to your vendor.

One other thing.. I've found that the simplest way to declare an emergency is to push the button and talk to give a vocal MAYDAY. Hitting the emergency button on the radio is a PITA when the radio is in the radio pocket or strap and the FF is wearing structural gloves. It can be done, with practice, but hitting the mike and talking is much easier.