Multiple rx repeater

[sjmark24]

Hey all, was wondering if there is a way to setup a repeater system to be monitoring multiple frequencies and transmitting it out onto one. Would this need to be done with a voting system or is there a repeater on the market that has the capabilities of monitoring 3 or 4 channels then transmitting on 1. I'm assuming things can get complicated when using a duplexer within the system as it would filter out the other rx channels.

Any help would be greatly appreciated. Thank you

 

[mmckenna]

A signal to noise voter would be used to pick the strongest signal and pass that to the repeater. If that's the function you were looking for, then that would be a good choice. Individual receivers would be connected to the voter. Those receivers could be all located locally, or spread around your area.
The way voters are often used is multiple receivers all listening on the same frequency. This can be a good choice if you are trying to improve receive coverage.

You could do a scan function, but the issue with scan is that it can miss the first bit of a transmission. Might be OK with your application, might not.
And, as for the duplexer, you'd be correct, it can be an issue, depending on how you have things set up. Running separate RX and TX antennas can solve that, but you'd need to notch out the TX frequency.

What is your end goal for this system? Is it improving talk in coverage, or is it to monitor multiple frequencies and send specific ones to the transmitter?

 

[sjmark24]

A signal to noise voter would be used to pick the strongest signal and pass that to the repeater. If that's the function you were looking for, then that would be a good choice. Individual receivers would be connected to the voter. Those receivers could be all located locally, or spread around your area.
The way voters are often used is multiple receivers all listening on the same frequency. This can be a good choice if you are trying to improve receive coverage.

You could do a scan function, but the issue with scan is that it can miss the first bit of a transmission. Might be OK with your application, might not.
And, as for the duplexer, you'd be correct, it can be an issue, depending on how you have things set up. Running separate RX and TX antennas can solve that, but you'd need to notch out the TX frequency.

What is your end goal for this system? Is it improving talk in coverage, or is it to monitor multiple frequencies and send specific ones to the transmitter?

Goal is to consolidate multiple repeaters spread across the area and have a central location that can receive all the repeaters and transmit out onto one main channel. all of the other repeaters are receiving the same handheld frequency and then repeating out onto a separate frequency. Id like to take all of those repeated frequencies and turn it into one channel.

 

[n5ims]

What problem are you trying to solve with that solution (assuming that it's an amateur radio repeater system since it's in that forum)? You would probably get lots of push-back trying to coordinate the various receive channels and this would confuse the typical ham user when what appears to be a repeater pair is receive only and transmits on some apparently unrelated frequency.

Extending your receive coverage is typically what a voting system is designed to do (and there are many ham repeater systems with voter receivers in remote locations that feed to the main repeater transmitter) and those remote receivers are on the same frequency as the main repeater. The voting system uses the RSSI value (typically) from the receivers to pick which one is retransmitted. It's smart enough to have voter 3 selected for one transmission and the main receiver for a reply (often even can switch voters when a mobile moves from one area to another during their transmission).

If you're trying to isolate some types of transmissions from another (say normal traffic from a net or even give certain nets special access), this can be done using PL tones or more often by programming the controller to work differently based on which mode is selected (the net's control operator will change the mode into the desired mode at the start of the net and set it back to normal at the end of the net). Often this is easier to accomplish than getting all of those voters to handle the multiple tones.

If you are attempting to do some cross-band action or even some type of remote base linked to the repeater, some of the higher end controllers often have those functions built in or at least available as options and will keep the system fairly simple. Users will also more easily understand how the system works as well.

If you really need to have multiple input frequencies go to a single output frequency, a voting system can handle it, but it may get confused and cut off the user on frequency C when a more powerful user keys up on frequency A and switch the output to that receiver. Now, that assumes that the various receivers are in different locations, or at least far enough away from the repeater transmitter to prevent desense. You are correct that the typical duplexer will generally not handle multiple receive frequencies as it must be tuned for both the input and output frequencies.

 

[mmckenna]

How are you going to handle multiple people talking on separate repeaters? Which one gets transmitted out your repeater?

Finding an audio switch would be an option. I seem to remember using one a long time ago in a PA application. Basically which ever input triggered first would get sent out. I'd have to do some thinking to remember what it was called.
Issue with that is a fault at one site could tie up your system. Issues on your link connections could fail to a state where it would key up your repeater.

I get the idea of what you would like to do, just trying to think about the issues you'd have to resolve.

A signal to noise voter would pick the active receiver. If multiple receivers were active, then you'd get which ever one had the better audio.

 

[n5ims]

Goal is to consolidate multiple repeaters spread across the area and have a central location that can receive all the repeaters and transmit out onto one main channel. all of the other repeaters are receiving the same handheld frequency and then repeating out onto a separate frequency. Id like to take all of those repeated frequencies and turn it into one channel.

OK, that answers many of my questions. It may be easier to use one of the various repeater linking solutions that are on the market and simply link them together. IRLP (IRLP - Internet Radio Linking Project) is one and All Star Link (https://allstarlink.org/) is another. Your existing repeaters would work as they currently do but any input on one would also be sent to all of those linked together at the time. One issue is that you will probably experience higher utilization on the repeaters since they're handling traffic from all that are linked, not just from their local area. This may cause them to run much hotter than normal since they're won't have as much time to cool off between transmissions.

Echolink (Introducing EchoLink) may also be a solution, but it generally isn't for full-time links but more often used for a temporary link between a user and a remote repeater.

 

[RFI-EMI-GUY]

Goal is to consolidate multiple repeaters spread across the area and have a central location that can receive all the repeaters and transmit out onto one main channel. all of the other repeaters are receiving the same handheld frequency and then repeating out onto a separate frequency. Id like to take all of those repeated frequencies and turn it into one channel.

If I read this correctly, you have a number of repeaters that receive portable traffic on one channel, let's call that F1, and each repeater transmits on F2, F3, F4, F5 etc.? Is this correct?

That is a multicast system. Usually a multicast system has a signal to noise voter ,like a JPS SNV-12 to select one transmission on F1 and retransmit on F2 through F5 etc.

However, you can have totally separate repeaters each receiving F1 and transmitting independently on F2 through F5 etc. It will work, but the likelihood of it working well is diminished.

If what you want is for all repeaters to receive F1 and transmit F2, it can be done and it is called Simulcast. You need the signal to noise voter and you also need hardware to synchronize the audio to all the transmitters . HARRIS synchrocast is one solution. You also need to have all the transmitters the exact same model and vintage, a GPS derived frequency and time reference. A CTCSS tone generator that is synched.

If this is what you seek, look up the webpage for Simulcast Solutions . Talk to Ed O' Conner there and he can help you work up a budget. His site has a wealth of information on doing this right.

You may have to be concerned with the limitations of simulcast when covering a huge county. This is where coverage modeling becomes important. You will need someone skilled in the art of simulcast computer modeling to determine which sites are useful for Simulcast.

Another alternative is DMR with IP site connect which can multicast transparently with automatic roaming. You will have to replace subscribers to enjoy that capability.

Drop me a PM with your phone number if you need to delve into these options further.

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[RFI-EMI-GUY]

OK, that answers many of my questions. It may be easier to use one of the various repeater linking solutions that are on the market and simply link them together. IRLP (IRLP - Internet Radio Linking Project) is one and All Star Link (https://allstarlink.org/) is another. Your existing repeaters would work as they currently do but any input on one would also be sent to all of those linked together at the time. One issue is that you will probably experience higher utilization on the repeaters since they're handling traffic from all that are linked, not just from their local area. This may cause them to run much hotter than normal since they're won't have as much time to cool off between transmissions.

Echolink (Introducing EchoLink) may also be a solution, but it generally isn't for full-time links but more often used for a temporary link between a user and a remote repeater.

The RTCM Allstar thin net client will do IP based voting and Simulcast. It's not quite ready for prime time for commercial use due to some issues with integrating an external GPS 9.6 MHz clock to fix a jitter problem. But folks have it working fine for ham radio. It is subject to the usual simulcast limitations.

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[prcguy]

If the goal is is to simply have a channel where one could here the output of several repeaters and its not a critical public service need, you could simply parallel a receiver for each repeater output frequency with a tone decoder for each and use that for keying this new repeater. During times were multiple inputs are active the system would just mix all the audios together and it would sound like more than one conversation going on at the same time, but at least you would be aware of the conversations and could probably pick out each one like sitting in a room with multiple people talking around you.

Not a very elegant solution but maybe it will work for the OP. The only other things to consider are input frequencies and how they relate to the output in needing receiver input filtering to avoid desense, etc.

 

[RFI-EMI-GUY]

A long time ago, in a distant galaxy, before such things as hand held scanners existed, I wanted to listen in on the cars and pit crews during an Indy race. I wired my Bearcat 210 scanner's discriminator to a low power Motorola PAC-RT and from anywhere on the track, I was able to listen to all of my favorite drivers radio traffic relayed from my car parked in the infield.

 

[K5MPH]

OK, that answers many of my questions. It may be easier to use one of the various repeater linking solutions that are on the market and simply link them together. IRLP (IRLP - Internet Radio Linking Project) is one and All Star Link (https://allstarlink.org/) is another. Your existing repeaters would work as they currently do but any input on one would also be sent to all of those linked together at the time. One issue is that you will probably experience higher utilization on the repeaters since they're handling traffic from all that are linked, not just from their local area. This may cause them to run much hotter than normal since they're won't have as much time to cool off between transmissions.

Echolink (Introducing EchoLink) may also be a solution, but it generally isn't for full-time links but more often used for a temporary link between a user and a remote repeater.

You can connect many repeaters and links to a conference server on Echolink......

 

[Project25_MASTR]

Yes, they did exist. Example, Motorola Quantar has a spare slot in the chassis for a secondary receiver and I used to have a GE Mastr Pro with dual receive. The real use is for bringing in a remote site but it could easily be adapted as a poor man’s voter.


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[AK9R]

Hey all, was wondering if there is a way to setup a repeater system to be monitoring multiple frequencies and transmitting it out onto one.

Is your theoretical system an amateur radio system?