Batboard

I think this can be done, but I’m not sure what would be needed.

We have 6 VHF “Analog” repeater sites, one in each county. Each site uses a different frequency. We are looking at ways to interlink these sites. A couple methods have already been looked at such as IP based, or microwave interconnection. The problem is that we only have about $5,000 per county, and can NOT have any re-occurring costs. I suggested that we place a VHF control station at each site. Each control station would have the other counties VHF frequencies. This control station would then be connected to the repeater via a wire-line interface, tone remote, or RICK or other method that could allow remote control for channel selections. I'm not sure what would be needed for this.
Sence I made the recommendation, I am being asked to provide details on how this would work, and what equipment would be needed.
For Example: County 1 VHF Repeater with Their Control station set to County 2 frequency. If County 1 keyed up a radio on County 1 it would be re-broadcasted to County 2’s repeater, and vice versa. This should allow cross county communications.
Am I thinking too simplistic here? I know It would not be perfect, and there may be some FCC issues involved, but I am trying to come up with some sort of solution for multi-County Interoperability on a shoe string..

Does anyone know of anything else that can do this? Recommendations?

Larry

Add a seventh repeater on a different band. Put it somewhere central to the other six. We’ll call it the hub repeater. The other six we’ll call repeaters “A”, “B”, “C”, “D”, "E" & "F". Configure each repeater with a half-duplex transceiver connected in. The half-duplex transceiver would be tuned to the frequency of the hub repeater.

Repeater “A” would receive it’s users on the input frequency and transmit that on it’s output frequency as normal. It will also transmit the ouput on the input of the hub repeater via the connected in transceiver. Repeaters “B”, “C”, “D”, "E", & "F" would receive the output of the hub repeater on their transceiver and transmit that on their regular unique output frequency. Give priority to each repeater to retransmit what is coming in on their regular input so if there is a problem somewhere else in the system they will still be able to communicate amongst themselves. You could also have control stations operating on the hub repeater frequency and be able to monitor & transmit to all.

Put a very short hang time or mute the CTCSS on the hang time of the hub repeater so it's hang time isn't retransmitted on the other repeaters, and configure your tranciever to operate at zero hang time. There are several inexpensive external repeater controllers that will perform this function and can be remotely controlled with DTMF if you want. You could even assign a unique DTMF address to each repeater & add them or remove them from the link as wanted. I would suggest the use of a pre- MDC type PTT ID just to force the users to wait a half second or so before speaking so everything has time to come up.

This set up works. The USFS does this to connect areas together on major wildfires, and I’ve seen ham systems done like this as well.

It is critical that the linking transceiver operate half-duplex otherwise it will lock itself up.

Go here for a pictogram from the NIICD for setting this up:

http://www.fs.fed.us/fire/niicd/docs/sy ... s_v5-0.pdf

Diagram 12 shows exactly what I am talking about and connects four repeaters but there is no reason you can't connect more.

If wirelines are an option and you want everyone on the repeaters to hear everyone on the other repeaters, what I would do is put all the repeaters receivers on the same receive frequency.

Tie everything back to a voter, then use the voter output to tie back to the wirelines of the repeaters transmitters, and "sloppy cast" it.

It's not necessary to actually change the receive frequencies, you could do it without changing receive frequencies, but doing so allows you to get true "best received signal quality" voting out of the system as an added bonus.

Otherwise if you leave the receive frequencies as-is, the voter can still function as a pass through to the transmitters.

I'll second the response by AI4UI about the hub repeater setup. I just built one of these with only three repeaters, but the concept is the same. One difference is that my hub repeater is hooked back to back with one of the primary repeater sites configured as a crossband repeater. I used UHF RKR1225 repeaters (with 100 watt PAs on the primary repeaters) and CM200s as the linking trancievers. I did this in-band, but I used physical seperation and BPBR duplexers to prevent desense. There were some interconnection issues with the CM200/RKR1225 when attempting a direct COR/PTT connection, probably due to the RKR1225 using 5 volt logic, and the CM200 using 3 volt. I went the cheap and dirty route and drove DIP relays with COR for PTT activation. After the initial setup in the shop, it was a throw down and walk away system with a happy customer glad to be rid of two cranky old Mastr II repeaters on short towers. Two 400 foot towers and one new 180 are much better than two OLD noisy 180 footers.

Kevin