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Thread: VHF Digital P25

  1. #41
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    Default Acu

    Quote Originally Posted by RadiomanWA View Post
    Analog only users will need something like this... http://www.raytheon.com/capabilities/products/acu_m/

    There are other models that can handle larger operations, but this one is a mobile type unit. You can connect 4 different types of radios or whatever..

    So, analog VHF <> P25 VHF. All you need to do is purchase 1-2 VHF P25 Radios and you can multi cast that over Analog. Working on tactical channels on scene usually only consist of 1-2 channels. As long as you know your surroundings (P25 info) you can pre-program the P25 radios for each mutual aid situation.

    Why purchase all new P25 Radio when you can add one of these to a vehicle that can be put on scene and relay all P25 digital conversations over Analog radios.
    These ACU devices, and others like them, are fine for situations where you'll have a trained radio tech right in front of them while they're in use. There are NOT (IMHO) a device you can turn your back on. We've had too many situations where radios start playing ping pong. One unkey causes another radio to key, and so on and so on... They'll work for hours just fine and then some combination of signals makes the radios go crazy and then it's all over for all the linked channels. They are like duct tape. They can save the day but you don't want any in a permanent system solution.


  2. #42
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    Default Narrowbanding and Simulcast

    Quote Originally Posted by wilcom8972 View Post
    So to recap, this is really a small issue since most departments have been buying radios from manufacturers who have been making this type of radio for over 6 years or more, you just dont know it. Just have your local radio shop do the programming or buy the software and cables and do it yourself. Its easy to do and I have done it several times in my county.
    One big catch in narrowbanding. If you're analog and you use simulcast, things get very expensive very fast.

    Simulcast means your system has transmitters that work together to give better talk-out range. They are timed using GPS to make sure they all transmit on the same frequency and at the same time so there is no interference and no echo effect. More sites transmitting means wider area coverage and far fewer dead spots. If you turn a corner away from one transmitter, there's a good chance you just turned toward another transmitter. Most trunking systems use simulcast but it's very common on conventional public safety systems. Just to give you an idea, one of our conventional dispatch channels would have about 5 TX/RX sites and maybe another 6 RX only sites. It's totally invisible to the users. But simulcast gets way more complicated when you need to narrowband it. The tolerances are already tight. Cutting the deviation in half makes it much more complicated. If your system does use simulcast, please let us know how things are looking for narrowbanding.

    The vendor's solution for this? Go digital. Many of the technical issues go away in digital. Of course, for the fire service, the problems digital brings are far worse.

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    Default

    Quote Originally Posted by RayVaughan View Post
    One big catch in narrowbanding. If you're analog and you use simulcast, things get very expensive very fast.
    Why does the narrowband simulcast get so expensive? I know in simulcast you have multiple sites, so each site would need to be worked on. So, for instance, narrowbanding a one repeater system would be 1X cost factor, while a three site simulcast would be 3X.

    We suffer from a few hills and ridge lines and nothing high enough in town to get 100% coverage. I think we are more than 95% portable coverage, but did solicit proposals to help get us to 100%. One proposal was a dollar sign followed by 6 digits, the other was much less (only five digits). In both cases, the vendors knew that we were already narrowband. I did not see anything in the proposals that would seem to change the price whether the system was wide or narrow.

    Brian

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    Icom has WSCA at 37.25% discount and the best match in P25 and Analog radios on the market now. Not only MIL spec but I.S AND Submersible. you can buy conventional analog, digital or digital capable.
    For more info and prices email me n8972@williamscom.com

  5. #45
    MembersZone Subscriber LVFD301's Avatar
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    Default

    Quote Originally Posted by wilcom8972 View Post
    Icom has WSCA at 37.25% discount and the best match in P25 and Analog radios on the market now. Not only MIL spec but I.S AND Submersible. you can buy conventional analog, digital or digital capable.
    For more info and prices email me n8972@williamscom.com
    Now, if we are going to start this stuff, then contact my son at Victor@frostytowers.com for prices on Icom.

    And his web page does not have equipment the FCC says you cannot use!

  6. #46
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    Default

    There's a really good article in the CSFA (California State FF Assoc) magazine last month giving watch outs and pro/con to various radio strategies. Check it out at
    http://legacy.csfa.net/csfamag/ca fire service nov-dec/index.html?pageNumber=12

    The bottom line is be careful! My own opinion: at least here in CA we have an outstanding mutual aid/interop radio plan that is 90% VHF analog. The system serves us very well and in my county, there is absolutely no reason to go digital for the moment.

    Somebody else stated that in the next 10 years, all the rules will change and technology will be turned on its head. Stick with what works for now, and change when there are compelling advantages to doing so.

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    Default Radio Guy Thoughts

    It is what it is. Not P25 but a good system. It is a ETSI DMR Tier 2 TDMA system that has the benefits of 2 voice channels per repeater. The radios meet high specs similar to a XTS and XTL series. The repeaters will operate dual mode so analog paging is still possible. The current repeater software supports 16 IP connected sites in any combination of 2 paths per site. The multisite trunking system is due to release soon. Avtec and Trbonet are releasing packages to direct control the repeaters at a console level. It's really a question of budget and what you can afford. I would fire your radio shope just yet. Hope that helps...

    RG

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    Default Narrowbanding Mandate

    As discussed above, there is no FCC requirement to go P25 when you narrowband. Further, narrowbanding only applies to VHF and UHF (including T-Band), not low band or high band.

    We've put together a website with all of this information, plus lots of FAQs. I will continuously update it as the FCC releases information.

    www.narrowbandinglaw.com

    ALAN S. TILLES, ESQ.
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    atilles@shulmanrogers.com | T 301.231.0930 | F 301.230.2891

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    Quote Originally Posted by LVFD301 View Post
    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.....
    I agree. It really is evil. Why would anybody want a public safety network in 800Mhz? The coverage with 800Mhz is extremely poor meaning that you will need tons of base stations...meaning that the network will be very expensive. Meaning that Motorola will earn tons of money! Another huge problem with P25 is the battery live. Since the P25 radios are continuously logged into the system the battery doesnt last longer than a day. And hey...there will never be any pagers for P25...who would want to carry around a 4 pound radio on his belt all day? I wouldnt!

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    Quote Originally Posted by RayVaughan View Post
    The vendor's solution for this? Go digital. Many of the technical issues go away in digital. Of course, for the fire service, the problems digital brings are far worse.
    What exact problems do you think fire departments would experience when going digital?

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    Default narrowbanding

    Quote Originally Posted by AlanTilles View Post
    As discussed above, there is no FCC requirement to go P25 when you narrowband. Further, narrowbanding only applies to VHF and UHF (including T-Band), not low band or high band.

    We've put together a website with all of this information, plus lots of FAQs. I will continuously update it as the FCC releases information.
    Hi Alan,

    What do you usually suggest to fire departments whose networks are not narrowband-ready? Do you propose to buy P25, DMR or stick with analog?

  12. #52
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    Quote Originally Posted by koechler View Post
    Hi Alan,

    What do you usually suggest to fire departments whose networks are not narrowband-ready? Do you propose to buy P25, DMR or stick with analog?
    Or Nexedge. Or IDAS. Or...... (DMR is certainly not the end all)

    There is no blanket answer for such a question. It depends on the area, the terrain, the adjacent users, etc.

  13. #53
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    Quote Originally Posted by koechler View Post
    I agree. It really is evil. Why would anybody want a public safety network in 800Mhz? The coverage with 800Mhz is extremely poor meaning that you will need tons of base stations...meaning that the network will be very expensive. Meaning that Motorola will earn tons of money! Another huge problem with P25 is the battery live. Since the P25 radios are continuously logged into the system the battery doesnt last longer than a day. And hey...there will never be any pagers for P25...who would want to carry around a 4 pound radio on his belt all day? I wouldnt!
    HUH?

    A properly designed 800 Mhz system can be a wonderful thing. Depending on the situation it can be the best way to go.

    P25 always logged into the system? Not following you there, what system are you talking about that causes such a thing? Where are you getting this misinformation?

    My P25 Icom radios batteries last longer than a day.

    While I know of no one planning a P25 pager - yet - it is possible. Most agencies I see that go P25 that need a paging solution either maintain an analog system for paging, or my favorite, use an alphanumeric system for paging. Cheaper, more reliable, more information, more flexible.

  14. #54
    Forum Member nmfire's Avatar
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    Default

    It's amazing the things people who have no idea what they're talking about manage to blurt out.

    LV- I got your email the other day. Sorry, I don't have any M5 codeplugs anymore and even if I did, they would all be single channel UHF or Low.
    Even the burger-flippers at McDonald's probably have some McWackers.

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    Quote Originally Posted by nmfire View Post
    It's amazing the things people who have no idea what they're talking about manage to blurt out.

    LV- I got your email the other day. Sorry, I don't have any M5 codeplugs anymore and even if I did, they would all be single channel UHF or Low.
    Thanks, I got it done - at least as far as I am going to try!

  16. #56
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    Koechler, you sure got quiet there....

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    Quote Originally Posted by LVFD301 View Post
    Koechler, you sure got quiet there....
    And that's why I like this forum. Knowledgable ppl calling you out on misinformation. Sorry I didnt reply earlier but I havent checked the forum message until today.

    I had an engineer explain it to me and you're right "constantly being logged in" was a nonsense statement. Just because its constantly listening to the control channel doesnt mean it causes the radio to consume more battery. The high battery consumption im comparison to other digital standards like NEXEDGE and DMR are due to other reasons. How long does the battery of your ICOM radio last?

    I guess I should specify when I say that a P25 system is not suitable for the fire service. I believe that it is not suitable for rural fire departments. Because of the high frequency used for P25 you would need a lot more base stations to cover the same area plus the equipment costs a lot more. I do believe, however, that any digital trunked system has clear advantages in high traffic urban areas as long as the radios are being switched to analog on the fireground (background noise problems)

    LVFD301, when would you recommend a fire department to go P25 and when not?

    Thanks for your help.

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    Quote Originally Posted by koechler View Post
    ....when would you recommend a fire department to go P25 and when not?
    If you are building a trunking system, it would be best to keep with the "standards". That standard is currently P25 and it works quite nicely. As long as you have analog non-trunked fireground channels available, it is fine.

    Anything else not trunked, there is absolutely no reason to go to digital modulation. You gain nothing and you lose interoperability. A salesman that tells you otherwise is a lying sack of $hit.
    Even the burger-flippers at McDonald's probably have some McWackers.

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    Quote Originally Posted by koechler View Post
    I had an engineer explain it to me and you're right "constantly being logged in" was a nonsense statement. Just because its constantly listening to the control channel doesnt mean it causes the radio to consume more battery. The high battery consumption im comparison to other digital standards like NEXEDGE and DMR are due to other reasons. How long does the battery of your ICOM radio last?

    I guess I should specify when I say that a P25 system is not suitable for the fire service. I believe that it is not suitable for rural fire departments. Because of the high frequency used for P25 you would need a lot more base stations to cover the same area plus the equipment costs a lot more. I do believe, however, that any digital trunked system has clear advantages in high traffic urban areas as long as the radios are being switched to analog on the fireground (background noise problems)
    OK, I have to call foul. Frequency has nothing to do with P25. You can do P25 on VHF (150-170MHz) or UHF (450-470MHz) or even in the 800MHz band. The bit about needing more base stations to cover an area is an untrue statement, all depends on topography and frequency band used, it has nothing to do with P25 Modulation.

    Radios on P25 Trunked systems do use a bit more battery as compared to a P25 radio on a conventional system as the reciever in the portable is constantly active monitoring the control channel. The radio uses the least amount of current in standby mode (doing nothing), a little more current when receiving signal (even control channel), a little more current when recieving and actually emitting audio out of the speaker and the most current when transmitting. You will experience longer run times per charge cycle on P25 conventional as compared to P25 trunking but battery capacities have been bumped to compensate. Normally not an issue. On trunked systems there are some cases in weak coverage areas when multiple sites are in range of a radio that may cause some higher battery drain if the radio switches sites frequenty. Every time the radio switches sites it transmits "affiliates" with the system and site and this does consume some battery, if the coverage area is weak and multiple sites are available the radio may switch sites and "affiliate" more often, although the logic that controls this does a pretty good job of limiting un-necessary affiliations, but it does happen.
    Last edited by sdff1520; 09-23-2010 at 09:13 AM. Reason: typo

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    Quote Originally Posted by sdff1520 View Post
    OK, I have to call foul. Frequency has nothing to do with P25. You can do P25 on VHF (150-170MHz) or UHF (450-470MHz) or even in the 800MHz band. The bit about needing more base stations to cover an area is an untrue statement, all depends on topography and frequency band used, it has nothing to do with P25 Modulation.
    I definitely agree on that but I havent seen many P25 systems on VHF/UHF. Can you provide some examples?

    Thanks.

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