VHF Digital P25

[cmjones]

Our county is looking at the VHF digital system. Anyone have experience with this system? We are currently on analog VHF.

[nmfire]

Your going to have to be much more specific than that. What kind of system. The word "system" means about 2,000 different possible things.

[cmjones]

Motorola MotoTrbo digital system.
http://www.motorola.com/business/US-...008406b00aRCRD

This system is being proposed to our county and was wondering if any public safety agencies are using this system. From what I understand Motorola has two different digital systems, this one and the Astro Digital.

I also understand that this is not P25.

[nmfire]

NO NO NO NO

Oh my god NO. Mototrbo is a BUSINESS system for use by commercial non-emergency simple uncomplicated single-site users. It is not and never was designed or intended for public safety or municipal use.

#1: Whatever motorola dealer is trying to sell you this, fire them and do not allow them to ever come back. They either don't know what they're doing or they are out to make a fast buck and don't actually care what they sell you as long as you buy it.

#2: The Mototrbo system will only work with Mototrbo radio, of which there is one portable and one mobile. Forget interoperability.

#3: The Mototrbo "repeater" is a single-site standalone unit. It doesn't do remote connection to a console. It doesn't do any kind of multi-site. You can't have remote receivers and a voter. You have one repeater and that is it, period.

#4: You can throw away your pagers since you can't page with it.

I say again, this is NOT for fire department and public safety use. Get the moron trying to sell you that out of your town before someone gets killed.

[cmjones]

Thanks for the info...From reading over it that was kinda the idea I got as well. Is the astro digital better on VHF? That would be P25 compatible right?

[ffarchitect]

Be very careful with the Digital "P25" systems in Fire Ground Use. Our dispatch center is trying to push a Motorola APX system down our throat. I realize that there is a mandate requiring everyone to go to narrowband by 2013, but I have also found out that there are several issues about using digital in the Fire Service. Just type P25 in google, and you will be amazed at the information out there, and none of it good for Fire Service use.

JMO, be careful out there.

B

[cmjones]

We wouldnt actually use the digital channels for fireground, we would switch to analog simplex channels. Only the IC would be monitoring the digital channel & the fireground channel.

[nmfire]

When you say "system", are you talking about conventional repeaters using P25? If so then you are wasting your money. Making a conventional channel operate in P25 gains you nothing except a bigger price tag and no interoperability with anyone. There is absolutely no reason or advantage to do it. It is totally irresponsible expense. I'm speaking not just as a resident communications geek but also based on personal experience in my town.

I'd also like to remind folks that NARROW BAND has absolutely nothing to do with P25 digital. There is not and never will be any requirement to go P25 digital. Do not let Motorola BS you into it.

[cmjones]

our story is the County has been looking at 800 Mhz but it costs too much so now they are looking for an alternative. Our state has a statewide 800 Mhz but they charge a fee per radio per month to use plus not good coverage in most of our county.

We have problems with skip and interference on the VHF analog, sometimes our pages are dropped and our dispatch has to tone multiple times. Adjoining county Receive frequency is our transmit freq (different PL) and when you first key the mike sometimes you can hear the other county.

[nmfire]

Well that's an even better reason to not go P25 digital. Digital doesn't overcome interference like that. In fact, it will just make it worse.

You should look at change your frequency. That's the only way to fix that kind of problem.

[MoosemanKBB527]

Be very careful with the Digital "P25" systems in Fire Ground Use. Our dispatch center is trying to push a Motorola APX system down our throat. I realize that there is a mandate requiring everyone to go to narrowband by 2013, but I have also found out that there are several issues about using digital in the Fire Service. Just type P25 in google, and you will be amazed at the information out there, and none of it good for Fire Service use.

JMO, be careful out there.

B

wait what... is this a nation wide mandate, NFPA or somthing else.
this can only be too good to be true.

a few years ago we had some a hole sell pour county on a low band simulcast system . that he pieced together and hasnt work right from day one,

[nmfire]

wait what... is this a nation wide mandate, NFPA or somthing else.
this can only be too good to be true.

a few years ago we had some a hole sell pour county on a low band simulcast system . that he pieced together and hasnt work right from day one,

Its an FCC mandate. Nothing to do with the NFPA and it is for everyone, not just the fire service. Public, private, commercial, etc etc. Anyone using VHF or UHF (150-500 for the sake of simplicity) is being required to migrate to narrowband operation. For the emergency services, that deadline is 2013.

Really old stuff is generally incapable of narrowband... simply because it didn't exist back then. But most public safety quality two-way radios manufactured in the last 10 years can do it. If you post what make/model radio you have, I can tell you if it will do it or not.

[MoosemanKBB527]

so this dosnt affect anyone using lowband (ie 40.00 - 50. 00)


and what is the difference between "narrowband" and uhf/vhf

[nmfire]

No effect on low band.

Narrowband is still UHF/VHF. I'll try to explain this in english the best i can. Each frequency takes up a certain amount of bandwidth. Think of a frequency as a stretch of highway. That highway has only one lane in each direction (bandwith). But they are big lanes, way bigger than they need to be. The road is congested and there isn't enough room for all the cars that need to use the road. So rather than one big lane in each direction, the DOT comes in and paints a dotted line down the middle. Now each big lane is split into two smaller lanes. The lanes still work just fine and it has doubled the amount of traffic the road can handle.

Typical UHF frequencies are spaced 25khz apart and each "channel" takes up a chunk above and blow that center frequency. Narrow band cuts that chunk in half. This effectively doubles the amount bandwidth out there for channel allocation.

[sdff1520]

#3: The Mototrbo "repeater" is a single-site standalone unit. It doesn't do remote connection to a console. It doesn't do any kind of multi-site. You can't have remote receivers and a voter. You have one repeater and that is it, period.

While I completely agree with your sentiments regarding TRBO not being a public safety radio solution and is instead a product intended for the business/commericial two way radio user, I feel I need to provide some information regarding multi-site use. MotoTRBO can in fact be set up as a multiple site system for wide area coverage. I don't recall the exact numbers for sure but thinking up to 15 repeaters can be linked via IP4 Ethernet connection sharing both voice & data (vehicle location, email, text messaging, telemetry, etc...) and offering seamless roaming with automatic site switching etc...no need for user intervention, changing channels etc... It is also possible to link TRBO repeaters operating in different bands, thus linking VHF and UHF TRBO users if need be. This system also allows for remote control and diagnostics of repeaters. No extra hardware required, the wide area IP Site Connect is built in to the repeater. Older TRBO repeaters manufactured before the introduction of the wide area feature simply need a firmware upgrade.

I agree that TRBO shouldn't be used for public safety as that was not its intended target market and your are completely correct in regards to interoperability. TRBO is propriatery and only a Motorola TRBO capable radios will operate on the system.

[nmfire]

Roaming and site switching. It isn't voting as far as i know. It just switches from one repeater site to another. Correct? There is still no such thing is trbo voting.

[sdff1520]

Correct, it is not a conventional voting system. The mobile and or portable radios select the best repeater site based upon signal quality and error rate and automatically switch frequencies to the appropriate repeater pair with no user intervention. The user simply needs to select the talkgroup they wish to use and the mobile takes care of selecting the actual frequencies to be used. The subscriber unit automatically registers with the site so any traffic (voice or data) intended for that subscriber unit is delivered to the appropriate site(s). It is not voting however, and thus a seperate pair of repeater frequencies is needed for each site (or at least the sites with overlapping coverage areas). To my knowledge a TRBO voting receiver system for the infrastructure side hasn't been developed at this point.

[LVFD301]

OMG. I can't believe I missed this. CMJONES, Everything MMFIRE has told you about your situation is corect. (The multi site from what I gather does not apply to your situation anyways)

There is NO requirement to go P25, with one caveat. In order to qualify for many grant opportunities you have to comply with your state interoperabilty plan when asking for communications equipment. As an example, in Missouri we have to ask for VHF P25 radios to comply with the state plan. (800 if we are within an UASI area)

You can check with your state office of emergency management to check compliance.

Mototrbo digital is not compliant with any state plan.

Your plan to keep fireground on analog is a good one.

Only unscrupulous Motorola dealers (Or any other manufacturer pushing
their own digital format) are pushing this for public safety, and it is evil.....

[LVFD301]

Also, Astro is not P25, while Astro 25 is......

[nmfire]

But its so much cooler to just say ASTRO! In the case of some /\/\ dealers I know, it is actually spelled ASStro.