Cullman County Fire-Going Digital

[jody_clarke]

Simply noticed this afternoon that Cullman County Fire Dispatch@158.745 had been testing out their new P25 radio system. Unsure if all the volunteer departments have new equipment yet or not, dispatch was toning out different departments last week for "meetings" to get new radios out. Didn't catch the NAC either as I didn't save it- seems like it was 116 or 119. Will update/correct NAC tomorrow, Am also unsure how the system will be set up, if their will be any changes to the current paging system or not- perhaps someone out there with more information than myself can bring some clarity to this. Seems I've brought more questions than answers to the issue- other than to say they are testing out the new system & are apparently getting closer to making the switch.

 

[puzzleriddle]

http://www.radioreference.com/apps/db/?fccCallsign=WNMN460

2 OF EMISIONS ARE NARROW BAND the e 1 that needs to be needs to be "watched "is 8K10F1W P25 Phase II subscriber units (Harmonized Continuous Phase Modulation - H-CPM)

 

[Avery93]

Simply noticed this afternoon that Cullman County Fire Dispatch@158.745 had been testing out their new P25 radio system. Unsure if all the volunteer departments have new equipment yet or not, dispatch was toning out different departments last week for "meetings" to get new radios out. Didn't catch the NAC either as I didn't save it- seems like it was 116 or 119. Will update/correct NAC tomorrow, Am also unsure how the system will be set up, if their will be any changes to the current paging system or not- perhaps someone out there with more information than myself can bring some clarity to this. Seems I've brought more questions than answers to the issue- other than to say they are testing out the new system & are apparently getting closer to making the switch.

For about the past month or so I've noticed that most, but not all of the County Fire units were using new Motorola P25 radios (in analog mode only). However when I was monitoring them Saturday and Sunday night, all of the units I heard had the new radios; so they are definitely getting very close to being able to convert.

Today I have been monitoring them since I saw this post a few minutes ago, and have only heard one digital keyup (146 NAC) and a few analog keyups (still 146.2 PL). If I had to guess, they will probably operate in mixed-mode with paging and interop on analog, and operations on P25.

2 OF EMISIONS ARE NARROW BAND the e 1 that needs to be needs to be "watched "is 8K10F1W P25 Phase II subscriber units (Harmonized Continuous Phase Modulation - H-CPM)

While 8K10F1W can indicate H-CPM, it is also used to indicate P25 Phase I voice and data under one emission mask. In this case it is almost certainly used to indicate the latter, as Phase II (TDMA) is currently limited to trunking systems; and I doubt County Fire spent the extra money on APX series radios just to be able to use Phase II in the future, if it is ever available for conventional systems.

 

[askdaniel1]

county fire

The NAC is 146. The PL will remain 146.2 . Mixed mode, full time.

Dispatch is (will be) analog, units will be p25 digital.
Testing and configuration still in progress. The radio vendor is handling all of this, and I have no direct relation to the project as I am not with that agency. (My agency does have interop with the county fire agencies though)

 

[puzzleriddle]

thanks Avery for clearing that uP

 

[KJ4TDM]

So any word on when they are going to make the full transition to digital?

 

[askdaniel1]

Like I said before, they aren't. It will be mixed mode, full time. Analog + digital. They will keep using quick call 2 tones in analog from the dispatch, the field users will be mostly digital but I imagine a good bit of analog will happen just due to programming/confusion/old radios.

 

[medic9351301]

ok what does this mean for analog users just dispatch heard with no units being heard or am i off base here

 

[CORN]

Sounds like if dispatch is gonna stay analog and the units are P25 and you have a analog scanner then yes, you will hear dispatch but the field units will sound like a awful jackhammer sound.

 

[Avery93]

ok what does this mean for analog users just dispatch heard with no units being heard or am i off base here

While I don't have any inside knowledge and only monitor Cullman County occasionally, It sounds like they will operate similar to Franklin County. They page in analog, immediately repeat the page in digital, and then all traffic after that is digital. For Franklin County, yes that means you would only hear the initial dispatch with an analog radio; however it sounds like County Fire will make greater use of analog.

Due to better mixed-mode support in the Motorola radios and (hopefully) better programming, I would also expect County Fire's dispatch process to be more streamlined (i.e. not having to repeat pages in digital).

This morning when County Fire was doing page testing, only the paging tones and alert tone were analog, all voice was digital. Hopefully this was just for testing, as this configuration doesn't make much sense. They also seem to be having quite a bit of problems getting the radios to reliably decode the paging tones.

 

[KJ4TDM]

Just my personal opinion, but to me that don't make much sense. Why do mixed mode? Either go digital or stay analog. What are they benefiting from by going mixed mode?

 

[Avery93]

Just my personal opinion, but to me that don't make much sense. Why do mixed mode? Either go digital or stay analog. What are they benefiting from by going mixed mode?

There are two very good reasons to operate in mixed-mode. The first is the ability to retain Quick Call paging, and by extension, Minitor type tone and voice pagers. The second, and more important reason is that it allows near-seamless interoperability with non-P25 capable agencies.

In my opinion, all conventional digital public safety systems should be programmed for mixed-mode operation, even if analog is only used occasionally for interop purposes. Of course, this also means that additional training on when and how to fall back to analog is needed, and it takes slightly more work to set up the system correctly. Because of this, many agencies take the 'easy' way out and don't bother to set up mixed-mode.

 

[KJ4TDM]

many agencies take the 'easy' way out and don't bother to set up mixed-mode.

Maybe one reason an agency don't do mixed mode is because they just bought a million dollar system and going to make use of it. Personally this is the first time i have heard of and agancy going half way so to speak. I'm sure there are others that are doing it to.

As for communicating with others that are not p25, you dont have to be mixed mode to do that. The dispatchers can patch p25 comms to analog comms, creating a mixed mode.

So, with P25, they cannot do 2 tone paging or Quick call paging?

 

[Avery93]

Maybe one reason an agency don't do mixed mode is because they just bought a million dollar system and going to make use of it. Personally this is the first time i have heard of and agancy going half way so to speak. I'm sure there are others that are doing it to.

I guess it does look like they would be sacrificing something by continuing to use analog after getting new digital radios, but if you think about it they're really not. If County Fire operates like other agencies, almost all two-way communication will be in digital mode. Only paging and the occasional interop with non-P25 agencies will be analog. The majority of the time, they will be enjoying the good audio quality, radio ID, and emergency signalling features P25 offers.

As for communicating with others that are not p25, you dont have to be mixed mode to do that. The dispatchers can patch p25 comms to analog comms, creating a mixed mode.

Patches require dispatcher intervention, and require additional infrastructure to be in place. With mixed-mode, all a non P25 user would have to do is key up on the analog side, and the repeater and subscriber radios will instantly and automatically receive the analog transmission. A Cullman unit would only have to switch to the analog transmit channel to talk back to the non-P25 user.

Mixed-mode is pretty much the simplest, easiest, and cheapest way to ensure interoperability with analog only radios. The digital users aren't sacrificing anything because most of the time the analog side will be unused and they won't even know it's there (except for paging). The only extra thing the digital users will have to deal with is the extra analog transmit channel, which is necessary because the transmit mode is strapped per channel.

So, with P25, they cannot do 2 tone paging or Quick call paging?

Nope. Analog signalling such as Quick Call, DTMF and MDC is incompatible with P25 because the vocoder distorts it so badly. Most of this is made up for by the signalling features built into the P25 CAI, but paging is somewhat lacking. There is individual selective calling and call alert, but this isn't really useful to VFDs because it is a one-to-one calling scheme. I believe there is also a group call alert (one-to-many) built into the P25 spec, but I've never heard of it being used and most radios appear to not support it.

 

[morganAL]

Call Alert works. I have seen it. So far, the only radios I know of that support on the receive side it are Motorola XTS and APX. XTLs may support it but not sure. The radios even support programming a button to mute the audio on the radio until a Call Alert is received.

Sending (at least in the Moto world) requires the MCC-7500 console. The MCC-5500 may support it but I have no experience with it. You are correct that groups can be built but the groups are made up of individual radios. When the Call Alert is activated, the system sends a Call Alert message to each radio that is to be alerted. The Call Alert message takes 300 milliseconds per radio. For a small VFD with 10-20 units, that isn't much different than the time it takes to send a 2-tone sequence. For a department with 100 radios, that is 30 seconds.

Of course you can do radio to radio Call Alerts but you can't build groups in the radio like you do the consoles.

The fact that none of the other manufacturers seem to support it to me is stupid on their part. Seems like a necessary feature to me.

Nope. Analog signalling such as Quick Call, DTMF and MDC is incompatible with P25 because the vocoder distorts it so badly. Most of this is made up for by the signalling features built into the P25 CAI, but paging is somewhat lacking. There is individual selective calling and call alert, but this isn't really useful to VFDs because it is a one-to-one calling scheme. I believe there is also a group call alert (one-to-many) built into the P25 spec, but I've never heard of it being used and most radios appear to not support it.

 

[bamabower]

Look like they went digital this afternoon, The tone is still analog but the voice is digital,

 

[KJ4TDM]

So when are they going to change the database for Cullman County?

 

[puzzleriddle]

So when are they going to change the database for Cullman County?

When eevr someone submits them