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  • Adding a tower to a repeater

    I'm not a radio guy, so hang with me here!

    Our district is mountainous. We are dispatched on a county-wide dispatch frequency and have several county operations channels we can use. We also have access to two company channels. 1 is simplex and one is duplex with the repeater tower located at our station 2, high atop a hill. The problem is we have a lot of dead spots, including most of the area around our station 1.

    I have read a little about repeater networks but can't find much about how they actually are set up. Would we need to acquire additional frequencies? (deal killer)

    Is there a simple way to add functionality to our station 1 area without breaking the bank? i.e. as simple as a new repeater, a new antenna, and some software magic.

    Thanks in advance!

  • #2
    First you need to be a little more specific about the nature of the problem. These dead spots, is it a problem with talking into the repeater with a portable/mobile, or a problem hearing the repeaters output, or both?
    Even the burger-flippers at McDonald's probably have some McWackers.

    Comment


    • #3
      Originally posted by nmfire View Post
      First you need to be a little more specific about the nature of the problem. These dead spots, is it a problem with talking into the repeater with a portable/mobile, or a problem hearing the repeaters output, or both?
      Trouble hitting the repeater from a portable mostly. We coordinate our response internally on this channel to not air all of our POV response on the county-wide frequency and often I'll show up at a scene and be surprised by the number of people there who claimed to have gone en route on the repeater. I think I mostly believe that they are making an attempt to transmit...

      We don't seem to have an issue with output once we actually hit the repeater... though I couldn't tell you off the top of my head the output power of the current setup. Like I said, I'm not the radio guy, but I am the ops captain so it technically falls under me.

      Comment


      • #4
        Ok. This is a very typical situation. You can fill in those dead spots with remote receivers. These remote receivers and you main repeater are all linked into a device called a voter (aka comparator). The voter picks whichever is receiving the best and sends that to the repeater transmitter. It is a pretty straight forward job, requires no additional FCC BS since it is only adding receivers, and the concept has been around since the 60's or 70's.

        The voter will run you $5000-$7000 new depending on how many line cards you need. Sometimes the local radio shops will have older ones removed from service that you can buy used for much less, like $1000, that work perfect still. The black GE voters are gold!

        The radio and pilot tone generator for the remote receiver, figure about $1,500 new. The challenge here is finding a place to put the radio and the antenna. The roof of tall buildings or a pole on high hilltop are ideal and require very little antenna/coax/install work. Putting it on an existing tower will add about $10,000 in tower work. And exiting site with receivers in your band and a multicoupler is gold.

        The most significant challenge is the backhaul. You need to get that audio from the remote receiver to the voter somehow. Your choices are leased RTPA circuits from the phone company ($$$), microwave ($$$), and RF links ($). If you an describe the terrain and obstacles between you main site and where you might put a receiver, I can go further.
        Even the burger-flippers at McDonald's probably have some McWackers.

        Comment


        • #5
          Originally posted by Firetacoma1 View Post
          I'm not a radio guy, so hang with me here!

          Our district is mountainous. We are dispatched on a county-wide dispatch frequency and have several county operations channels we can use. We also have access to two company channels. 1 is simplex and one is duplex with the repeater tower located at our station 2, high atop a hill. The problem is we have a lot of dead spots, including most of the area around our station 1.

          I have read a little about repeater networks but can't find much about how they actually are set up. Would we need to acquire additional frequencies? (deal killer)

          Is there a simple way to add functionality to our station 1 area without breaking the bank? i.e. as simple as a new repeater, a new antenna, and some software magic.

          Thanks in advance!
          Can you get your repeater antenna higher?

          Why can you not have additional frequencies? In Colorado there are a number that have become available after the new state system went in.

          Vehicle repeaters perhaps?

          Voters like MM suggests?

          Comment


          • #6
            What NM & LV have both asked are the most important questions,

            We went to a voted receiver system and improved our portable coverage area to almost 98
            % of our town from about 80% with a duplex single site repeater.. out terrain was the problem also , radio waves don't penetrate iron laden rock very well. Elevation is key , or add fill in receiver sites until the coverage is excellent.

            Have you done an RF study to see what the coverage area is from your current site?

            We went with 4.9ghz microwave links for the tie line or backhaul as the cost long term for a dedicated phone line was astronomical over time. A continuous duty UHF radio will also do it at a lower cost.

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            • #7
              If you have to go back to coordination (for more than one site), try to keep your VFH (150.xxx) frequencies. Use 460.xxx mHz and crossband the transmit to the primary tower. It should be easier to get approved for the sites and frequencies. The 460.xxx will not have the same penetration or RF issue that 150.xxx will using the same power... and you might be able to use low-power transmitters if you are lucky and have line of sight.

              We use three secondary towers with a common secondary receiver. If the user cannot hit the primary, then he selects the closest tower; N, SW or SE to establish contact. We use 25watts on 460.xxx to link to the primary. The repeater receives either the 154.xxx or the 460.xxx and rebroadcast (repeats) the transmission on the primary 154.xxx VHF frequency.

              We use one single UHF 460.xxx frequency with each VHF channel on the transmitter using a different PL tone for each sub-tower. That way we avoid the issue if two towers try to intercept and vote the signal. We tried to combine the three towers to one single PL and had alot of issues with vote switching between towers during transmissions.

              If there is a will... there is a way.
              HAVE PLAN.............WILL TRAVEL

              Comment


              • #8
                Originally posted by nmfire View Post
                Ok. This is a very typical situation. You can fill in those dead spots with remote receivers. These remote receivers and you main repeater are all linked into a device called a voter (aka comparator). The voter picks whichever is receiving the best and sends that to the repeater transmitter. It is a pretty straight forward job, requires no additional FCC BS since it is only adding receivers, and the concept has been around since the 60's or 70's.

                The voter will run you $5000-$7000 new depending on how many line cards you need. Sometimes the local radio shops will have older ones removed from service that you can buy used for much less, like $1000, that work perfect still. The black GE voters are gold!

                The radio and pilot tone generator for the remote receiver, figure about $1,500 new. The challenge here is finding a place to put the radio and the antenna. The roof of tall buildings or a pole on high hilltop are ideal and require very little antenna/coax/install work. Putting it on an existing tower will add about $10,000 in tower work. And exiting site with receivers in your band and a multicoupler is gold.

                The most significant challenge is the backhaul. You need to get that audio from the remote receiver to the voter somehow. Your choices are leased RTPA circuits from the phone company ($$$), microwave ($$$), and RF links ($). If you an describe the terrain and obstacles between you main site and where you might put a receiver, I can go further.
                This may be the ticket... the problem is remote mountainous areas without power sources. We had our officer meeting tonight and I delegated the main bulk of this task to my comms officer. I will forward him this information and give him a pat on the back! I knew if you saw this I could get a good answer!

                Comment


                • #9
                  Originally posted by LVFD301 View Post
                  Can you get your repeater antenna higher?

                  Why can you not have additional frequencies? In Colorado there are a number that have become available after the new state system went in.

                  Vehicle repeaters perhaps?

                  Voters like MM suggests?
                  We could get the repeater antenna higher, but not higher than the surrounding mountains without going WAY higher unfortunately.

                  I suppose I shouldn't say we won't add additional frequencies, but we'd like to avoid it if possible.

                  I had thought about vehicle repeaters... I don't know much about them...

                  Comment


                  • #10
                    Can you tell me what the location of this is so I can check it out on google maps with terrain. PM is fine if you don't want to post it.

                    It sounds like remote receivers on one or more of the hill tops could probably fill in the areas that those hills shadow from the main site. So your two challanges will be power and backhaul to the main site.

                    If there are no roads with power lines running along them in the area you need the receiver, this is a problem however not one that hasn't been overcome before. Big marine batteries and some solar panels will get you running. A receiver site uses very little power.

                    The backhaul will probably have to be point-to-point RF rather than leased phone circuits since it sounds like there isn't a phone line in sight. You'd have to license a VHF or UHF link frequency (pretty simple) and put a link transmitter at the remote site and a link receiver at the voter.

                    To keep equipment and costs to a minimum, something like a Motorola CDR500 makes a good remote receiver and link setup. It is basically two mobile radios and a link box. One receives on your input, one transmits on the link frequency. It's all 12 volt and can run off the batteries. Now, I could build this thing myself for $500 complete (done it before). But in the absence of a local geek, Motorola sells it as a package. High gain antenna for your receiver radio and a directional yagi on your link radio pointing at the main site.
                    Even the burger-flippers at McDonald's probably have some McWackers.

                    Comment

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