As the title states I am wanting to link two analog UHF repeaters that are about 75 miles apartment (which will have an overlapping coverage area). How do I do this??
I am open to linking through the internet, or through a RF link, But I need to know the basics from theory to possible hardware selection?
Thanks, Rob
Also, If there is any specific info on the internet stuff pls post (this is not a ham box so none of the wires or echolink stuff will work) This might be from CPU to CPU through high speed cable service.
P.S. I have looked at the VEGA unit that coverts this, But they are $$$$$$-there has to be a cheaper method, this type of technology I wouldn't think would cost this much.
Tell me about simulcasting/linking two repeaters???
Moderator: Queue Moderator
Sorry,
Both of the repeaters will be on the same freq.
One system is up and running. I am adding a Doug Hall voting system to increase the main sites RX coverage. As we are testing we feel the need to increase the TX range of the main repeater to cover east of us.
So, We have another possible site, and are wanting to set up an identical repeater possibly with voting as well.
BUT
We want seemless coverge (so to speak) Same Freq and PL, so this way you can travel between coverage areas without having to cahnge channels
Hope this helps. Rob
Both of the repeaters will be on the same freq.
One system is up and running. I am adding a Doug Hall voting system to increase the main sites RX coverage. As we are testing we feel the need to increase the TX range of the main repeater to cover east of us.
So, We have another possible site, and are wanting to set up an identical repeater possibly with voting as well.
BUT
We want seemless coverge (so to speak) Same Freq and PL, so this way you can travel between coverage areas without having to cahnge channels
Hope this helps. Rob
Well that's going to be a problem. Unfortunately, you can't just key up both transmitters on the same frequency at the same time where there is overlap. Have you ever heard two mobiles or portables transmit at the same time? All you hear is wahahergilzzzerbalalawahahahahaha-squack. That's all you are going to get if you key up two base transmitters at the same time.
To do what you want, you will need a true syncronized simulcast system. These use GPS time-syncronized controllers, special transmitters that meet certain specs, and a control infrastructure that is up to the task. I don't think a typical RF Yagi link will do it. Microwave or leased lines are required. It is astronomicly expensive!
You might be better off using a different TX frequency at the other site and switching channels if it is breaking up. You would have the same RX frequency and simply have the voter key up both transmitters.
To do what you want, you will need a true syncronized simulcast system. These use GPS time-syncronized controllers, special transmitters that meet certain specs, and a control infrastructure that is up to the task. I don't think a typical RF Yagi link will do it. Microwave or leased lines are required. It is astronomicly expensive!
You might be better off using a different TX frequency at the other site and switching channels if it is breaking up. You would have the same RX frequency and simply have the voter key up both transmitters.
"I'll eat you like a plate of bacon and eggs in the morning. "
- Some loser on rr.com
eBay at it's finest:
Me: "What exactly is a 900Mhz UHF CB?"
Them: "A very nice CB at 900Mhz speed!"
- Some loser on rr.com
eBay at it's finest:
Me: "What exactly is a 900Mhz UHF CB?"
Them: "A very nice CB at 900Mhz speed!"
I don't know that the description of "astronomicly expensive" is quite correct. But as Matt says above, it is quite a bit of work, and costly.
You MUST have very consistent "signal transport" between your two sites, and syncronized or Hi-Stab oscillators. And audio delay, for both voice audio, and if used for your PL.
It can be worth the money in the several year run, but there is no cheap way to do it.
It would be much cheaper and easier to get another pair and "muticast".
Even if you have to add freqs to a fleet of radios, that is cheaper than simulcast.
Second best option is "transmitter steering", using the rx voter to decide which transmitter to rebroadcast on.
Do a search on "simulcast" and you will find a lot of discussions about simulcast.
Personally, I like simulcast. But it requires a lot of up front work, and a bit of maintenance.
Even with that, you will have overlap areas where it sounds kinda crappy.
You MUST have very consistent "signal transport" between your two sites, and syncronized or Hi-Stab oscillators. And audio delay, for both voice audio, and if used for your PL.
It can be worth the money in the several year run, but there is no cheap way to do it.
It would be much cheaper and easier to get another pair and "muticast".
Even if you have to add freqs to a fleet of radios, that is cheaper than simulcast.
Second best option is "transmitter steering", using the rx voter to decide which transmitter to rebroadcast on.
Do a search on "simulcast" and you will find a lot of discussions about simulcast.
Personally, I like simulcast. But it requires a lot of up front work, and a bit of maintenance.
Even with that, you will have overlap areas where it sounds kinda crappy.
-
psapengineer
- Posts: 175
- Joined: Thu Oct 07, 2004 10:00 am
Simulcast
True simulcast is an expensive task and an artform. A good explanation can be found at: http://www.simulcastsolutions.com/case-studies.htm
My two bits worth:
Having worked on simulcast systems from the Motrac days, I observe that
"the sum is less than the whole"
That is, the coverage from the two sites is not the same as both sites individually.
Capture areas are where you hear just one site, 20Db or so stronger than the other sites.
The problem is with the "Area of Non Capture"
This is where you hear both stations, at about the same signal level.
If the audio phasing should be over 45 deg the recovered audio will be un intellagable.
Some systems use directional antennas to minimise the area of non capture.
There is also problems with beating of PL tones, as well as the RF carrier.
Voting comparators like to choose between "Good" and" Excellent"
Not" lousy, and noisy"
75 miles between sites seems a bit much to me.
If you want true seamless coverage you might have many more sites involved.
In my opinion, the "Multi cast" option is the way to go.
You could allow your mobile receivers to scan, using a common site receive channel for the complete system.
Having worked on simulcast systems from the Motrac days, I observe that
"the sum is less than the whole"
That is, the coverage from the two sites is not the same as both sites individually.
Capture areas are where you hear just one site, 20Db or so stronger than the other sites.
The problem is with the "Area of Non Capture"
This is where you hear both stations, at about the same signal level.
If the audio phasing should be over 45 deg the recovered audio will be un intellagable.
Some systems use directional antennas to minimise the area of non capture.
There is also problems with beating of PL tones, as well as the RF carrier.
Voting comparators like to choose between "Good" and" Excellent"
Not" lousy, and noisy"
75 miles between sites seems a bit much to me.
If you want true seamless coverage you might have many more sites involved.
In my opinion, the "Multi cast" option is the way to go.
You could allow your mobile receivers to scan, using a common site receive channel for the complete system.
Aloha, Bernie
UHF Multi Site repeaters
[quote="bernie"]My two bits worth:
Having worked on simulcast systems from the Motrac days, I observe that
"the sum is less than the whole"
That is, the coverage from the two sites is not the same as both sites individually.
.[/quote]
Bernie hit the nail with the hammer. You would be much better off with going and getting another pair of frequencies and just setting up the system as 2 different channels. Make on the East and the other West or what ever your going to use them as.
Even using a common input with the repeaters this far apart is asking for problems. If nothing else, use a different input tone. Then you could use the same output frequencies. Just don't try to bring them up together.
The state of New Hampshire usies a system like this for the Fish and Game radio system. They have repeaters all over the state. They use a common RF channel, just change the input tone squelch to select the location they want. If your in between two repeaters, the one selected comes up. You have a better chance of hearing. If your having problems, ask the other person to switch and see if the other repeater is any better.
Many states use this type of multi site system. Some even tie multi sites together, but are careful in the frequencies used and the site spacing apart to make it work. They link them via microwave normally.
Jim
Having worked on simulcast systems from the Motrac days, I observe that
"the sum is less than the whole"
That is, the coverage from the two sites is not the same as both sites individually.
.[/quote]
Bernie hit the nail with the hammer. You would be much better off with going and getting another pair of frequencies and just setting up the system as 2 different channels. Make on the East and the other West or what ever your going to use them as.
Even using a common input with the repeaters this far apart is asking for problems. If nothing else, use a different input tone. Then you could use the same output frequencies. Just don't try to bring them up together.
The state of New Hampshire usies a system like this for the Fish and Game radio system. They have repeaters all over the state. They use a common RF channel, just change the input tone squelch to select the location they want. If your in between two repeaters, the one selected comes up. You have a better chance of hearing. If your having problems, ask the other person to switch and see if the other repeater is any better.
Many states use this type of multi site system. Some even tie multi sites together, but are careful in the frequencies used and the site spacing apart to make it work. They link them via microwave normally.
Jim