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narrowband-ready?

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  • onlocation
    replied
    My department has made the switch and every thing went flawlessly. We went from wide band to narrow band and also added a P25 digital channel. We pretty much stay on the narrow band channel due to our pagers. This way members without radios and/or scanners can here the traffic. However sometimes we will switch over to our digital channel to clear up our page channel for fire scene operations. We also at this time still have our old wide band channel. Only the department has this channel, dispatch doesnt even have it anymore. We have been using it for a car to car channel between members whenever they need to talk to one another. Kind of handy, but I am not sure how much longer we will have it. Our digital channel has been working great, however, the sherriff's department just switched to digital also and theirs has a lot of "warble" noise and missed communications. The census is they still have something screwed up in the programming.
    Our department has come a long ways from having an old wide band, repeaterless channel to having a 150 watt repeater and radios on narrowband and a digital channel and almost every member having a P25 handheld so I cant help but feel this is a step foward.

    Leave a comment:


  • tree68
    replied
    Originally posted by koechler View Post
    Hi Tree, how do they deal with it?
    At present, they don't.

    What they could do is set up a "gateway" such as they have for talking to the various outside agencies (fire, sheriff, city police and fire, state police) which simply becomes another talkgroup on the system. Since almost all of the buildings involved are within range of the main repeater site, dispatch would hear most of the traffic.

    Of course, if the handhelds could hit the repeater from inside the buildings, it wouldn't be an issue in the first place, but much of the simplex traffic would still be heard.

    Since it would be on a talkgroup, it could also be recorded, something not possible right now.

    One valid concern with going to the simplex channels is that the users are now "off net," so if they hit their emergency button, it won't register with dispatch. The simplex channels are still digital, so an emergency will still register with all of the other radios on simplex, but not with dispatch.

    There are probably other solutions - that's what I'm familiar with.

    Another is not to worry about it. If I am running a scene properly there is no reason for dispatch to be listening to my fireground.
    This agency has a standard FG talkgroup for most incidents. In fact, most of the firefighters leave their handhelds set to that talkgroup. If the IC wants to communicate with dispatch, there's no need to go back to the dispatch TG, he can just call them on FG. Keeps the dispatch TG clear.

    The daytime population of the installation is in excess of 20,000, and the hazards covered range from housing areas to industrial areas to an airfield to the gunnery ranges - 165 square miles.

    Leave a comment:


  • koechler
    replied
    Originally posted by LVFD301 View Post
    Remote recievers microwaved back to dispatch is one way.

    Another is not to worry about it. If I am running a scene properly there is no reason for dispatch to be listening to my fireground.
    Got ya. Thanks.

    Leave a comment:


  • LVFD301
    replied
    Originally posted by koechler View Post
    Hi Tree, how do they deal with it?
    Remote recievers microwaved back to dispatch is one way.

    Another is not to worry about it. If I am running a scene properly there is no reason for dispatch to be listening to my fireground.

    Leave a comment:


  • koechler
    replied
    Originally posted by tree68 View Post
    On top of that, their dispatcher can monitor all of the talkgroups, with the exception of the simplex fireground, and that can be dealt with as well.
    Hi Tree, how do they deal with it?

    Leave a comment:


  • tree68
    replied
    Having implemented a military installation digital P25 system, all of the comments are right on.

    Because it's theoretically possible to lose the entire system, I started from day one with several simplex channels, which were programmed into all radios. When it came time to do a full system service (one tower at a time), that planning paid off, albeit with many of the same limitations that existed on the system when they were using an analog system.

    Once they got over the culture shock, the users have come to like the system (some deep seated distrust still exists). Outside, coverage is near 100% throughout the area covered by the system, and we've successfully tested to nearly 20 miles in all directions with handhelds.

    Although I heard recently that the fire department wants to go back to an analog system. For some reason they can't get it into their heads that they've got a system right now with more talkgroups than they usually use, and have the simplex fireground they need for on-scene ops (there are many buildings that lose the repeaters as soon as you step in the door).

    On top of that, their dispatcher can monitor all of the talkgroups, with the exception of the simplex fireground, and that can be dealt with as well.

    A county near Syracuse needs something like 13 repeater sites to cover their area due to the terrain.

    Leave a comment:


  • LVFD301
    replied
    Daryl's blog has some good information, but some of what he posts is biased and extreme.

    P25 has its place. A well designed P25 system can rock. (NEVER, i said NEVER use digital or repeated fireground channels though)

    A poorly designed analog system sucks. A poorly designed P25 system can suck.

    P25 will help to recover some coverage issues due to narrowbanding.

    Leave a comment:


  • islandfire03
    replied
    Good article , but mostly a rehash of what several of us here have been preaching for a couple years.

    Don't get sucked into buying a half designed system based on your budget or the promises of a radio salesman.
    Do not allow some town/city/ county administrator to make purchasing decisions when it comes to public safety communications systems.

    Digital APCO p-25 systems are inherently complicated by design and making them work properly is not an easy or inexpensive task.
    there are many examples of regional systems that were installed with the promises of perfection. When it came to testing them , it was found that they had less than 50% coverage or that it just couldn't be made to work without doubling or tripling the amount of infrastructure.

    a contract that starts at $$$$ goes to $$$$$$$$$$$$$$$ when trying to retrofit a patch or redesign after the fact to make something work the way that the salesman promised the administrator.


    Tower sites and required land acquisition cost can get very expensive, Leasing space on commercial towers is an ongoing expense that most systems can't afford, and they are not available in a large part of rural areas.

    Far too many people are losing sight of the KISS principle. Keep the equipment simple and firefighter proof, make it so it will work anywhere , anytime without relying on high technology to make it work.

    The best example of this I can think of is two radio grant apps from 2007 AFG that I worked on.
    Both had the same number of mobile & portable radios. same coverage areas, similar terrain.

    System #1 was based on an analog VHF narrowband system.

    #2 was based on an 800 mhz trunked system where they had to purchase from one vendor
    due to a proprietary system design

    System #1 was completed and successful for the cost of $60,000 with a 99% area coverage and done keeping the KISS principle in mind.. I say 99% coverage because there is no such thing as a perfect system.
    Not too many folks really need or can use a full trunked multi bank system.
    Most cannot afford it.

    System #2 was completed for an initial cost of $172.000 with an additional expenditure after installation of $56k to install interior receiver antennas in many office buildings and big box stores so they could actually use and communicate on the new equipment. This is not including the cost of the existing infrastructure which had been previously installed & paid for.

    Leave a comment:


  • koechler
    replied
    Aren't you guys worried about switching to P25 with all the bad press out there? I just read the article on the front page of this blog and it gives me the shivers.

    http://blog.tcomeng.com/

    Don't you also somehow loose the ability to have an open channel in a digital trunked system? I was told that the switch will just break down if it has to connect to too many digital terminals at once.

    The same will happen if you use a talk group for a fire incident and tons of people switch to this talkgroup just to listen in.

    Are people just bad-mouthing P25 for no good reason or is there something behind this bad press that should make us reconsider paying all this money?

    Leave a comment:


  • islandfire03
    replied
    Originally posted by sapper937 View Post
    i personally hate narrow band doesnt work for crap in my area we are lucky if we can hear anyone else that is responding due to interference from mountians and what not in our area
    My guess would be that your wide band system used previously was marginal at best and switching to narrow band with out a propagation study being done is why you are experiencing issues.
    System design for any radio network is a very important part of the program. You can't just take the word of a salesman that it will work fine. You need an engineer to design the right equipment to make it work without problems when you get into mountainous terrain .

    Leave a comment:


  • tree68
    replied
    Originally posted by LVFD301 View Post
    I hate that you have a poorly designed system. That must suck.
    +1

    At least we know why our system used to suck worse than it does today - when it was implemented there were no pagers or hand-helds. It was intended to set off firehouse sirens and talk to fire trucks.

    Leave a comment:


  • LVFD301
    replied
    Originally posted by sapper937 View Post
    i personally hate narrow band doesnt work for crap in my area we are lucky if we can hear anyone else that is responding due to interference from mountians and what not in our area
    I hate that you have a poorly designed system. That must suck.

    Leave a comment:


  • sapper937
    replied
    i personally hate narrow band doesnt work for crap in my area we are lucky if we can hear anyone else that is responding due to interference from mountians and what not in our area

    Leave a comment:


  • tree68
    replied
    Originally posted by koechler View Post
    Are you going to keep the VHF frequency for paging only? Are you using analog or digital POCSAG/Flex?
    There's a lot of "what if" still floating around that - it'll depend on which way we end up going, ie, trunked or VHF-High repeated.

    Our paging is currently analog, two-tone sequential for the most part. The only digital is the secondary notification via cell phone texts. Given that most everyone who uses the texting (direct from dispatch is only the chiefs, but we use Google and Yahoo groups, among others, to spread the info to any member who wants it), changing over to a pure text notification might be better received than it would have been a few years ago. A lot of people like to be able to monitor what's going on with their neighbors (and the rest of the county).

    Island - We have the St Lawrence Seaway for a "neighbor." I'm sure we have many of the same venues you have for funding. We are currently working on/with a multi-county consortium so we can work the issues (and solutions) together.

    Leave a comment:


  • koechler
    replied
    Originally posted by tree68 View Post
    Figuring an average of 10 mobile and 10 handheld radios per fire department, that's upwards of $60-70,000 per department for new radios. While we've implemented VHF-High paging, some departments are still using the low band frequency (they are simulcast).
    Are you going to keep the VHF frequency for paging only? Are you using analog or digital POCSAG/Flex?

    Leave a comment:

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