Repeater to repeater coms

[WRVG593]

I'm fairly new to GMRS so forgive my lack of knowledge. 

Is it possible to take a repeater whose Channel/Frequency is 15/462.550 (offset of 5 mhz) and have that repeater spit out a 467.550 Mhz transmission that connects to other repeaters owned by the same person, eliminating the need for an offset and just utilizing 467.550 as opposed to adding an offset, causing unwanted listeners to not hear? Or even connect it to a repeater far away and increase the range from 50 miles to 100? Or would It spit back at the repeater it came from? Could you not set up a timer before it can accept the next transmission?

[SteveShannon]

52 minutes ago, WRVG593 said:

I'm fairly new to GMRS so forgive my lack of knowledge. 

Is it possible to take a repeater whose Channel/Frequency is 15/462.550 (offset of 5 mhz) and have that repeater spit out a 467.550 Mhz transmission that connects to other repeaters owned by the same person, eliminating the need for an offset and just utilizing 467.550 as opposed to adding an offset, causing unwanted listeners to not hear? Or even connect it to a repeater far away and increase the range from 50 miles to 100? Or would It spit back at the repeater it came from? Could you not set up a timer before it can accept the next transmission?

As I recall, from a regulatory perspective, repeaters are not explicitly permitted to transmit on the 467 MHz channels. 

[MichaelLAX]

1 hour ago, WRVG593 said:

I'm fairly new to GMRS so forgive my lack of knowledge. 

Is it possible to take a repeater whose Channel/Frequency is 15/462.550 (offset of 5 mhz) and have that repeater spit out a 467.550 Mhz transmission that connects to other repeaters owned by the same person, eliminating the need for an offset and just utilizing 467.550 as opposed to adding an offset, causing unwanted listeners to not hear? Or even connect it to a repeater far away and increase the range from 50 miles to 100? Or would It spit back at the repeater it came from? Could you not set up a timer before it can accept the next transmission?

Let's see if I get the principle espoused here:

User 1: Transmits on 462.550/listens on ???

Repeater 1: Receives User 1's signal on 462.550 and retransmits it on 467.550

Repeater 2: Receives Repeater 1's signal on 467.550 and retransmits it on ???

User 2: Transmits on ??? and receives on ???

I need more explanation of your theory I guess.

[WRVG593]

42 minutes ago, Sshannon said:

As I recall, from a regulatory perspective, repeaters are not explicitly permitted to transmit on the 467 MHz channels. 

Well what if they were to offset -3Mhz instead? Or are all of them regulated to be offset by 5mhz so that general FRS radios are unable to communicate with it?

[MichaelLAX]

4 minutes ago, WRVG593 said:

Well what if they were to offset -3Mhz instead? Or are all of them regulated to be offset by 5mhz so that general FRS radios are unable to communicate with it?

So now the Repeater is retransmitting on 459.550 or 465.550; not clear which one you are proposing?

These frequencies are not within the GMRS band: maybe you are clobbering your local fire department's attempt to put out the fire at your residence?!?

Oh, and what does FRS have to do with it?

[WRVG593]

1 minute ago, MichaelLAX said:

Let's see if I get the principle espoused here:

User 1: Transmits on 462.550/listens on ???

Repeater 1: Receives User 1's signal on 462.550 and retransmits it on 467.550

Repeater 2: Receives Repeater 1's signal on 467.550 and retransmits it on ???

User 2: Transmits on ??? and receives on ???

I need more explanation of your theory I guess.

So my theory goes as follows-

Set your HT or Mobile(if possible) to TX on 467.550. So...

User1: TX on 467.550 onto repeater1

Repeater1: catches the signal and puts out 467.550 to radio listening units and more importantly repeater2, shuts off possible incoming traffic for however long the transmission is.

Repeater2 catches, pushes out 467.550 as well. 

Keeps general FRS radios from hearing, and interfereing

[WRVG593]

3 minutes ago, MichaelLAX said:

So now the Repeater is retransmitting on 459.550 or 465.550; not clear which one you are proposing?

Oh, and what does FRS have to do with it?

The 465.550, although it's flawed thinking. And the FRS was just about not wanting general FRS radios (listening on 15) to hear the traffic

[WRUU653]

2 minutes ago, WRVG593 said:

FRS was just about not wanting general FRS radios (listening on 15) to hear the traffic

Whyyyy wouldn’t FRS listen on 15? 
 

[WRVG593]

1 minute ago, WRUU653 said:

Whyyyy wouldn’t FRS listen on 15? 
 

If transmission was on 467.550, frs radios would not be able to pick up. They would only be able to pick up 15/462.550. The 5mhz would prevent them from hearing. 

[MichaelLAX]

No established way to avoid being heard on FRS radios when using GMRS per the rules; maybe MURS?

I still don't understand the repeater scenario 100%, but at the end of the day, transmitting on 467.xxxx is supposed to be used only for Repeater inputs.

I suppose you could try it, but now that you discussed it here, the FCC office in Cincinnati will be scanning nearby your home!!! [laughing emoticon seems to be missing!]

[WRUU653]

Got it. I got lost in the theory of what frequencies were receiving and transmitting and by what. 

[MichaelLAX]

Just so you will know, I did modify my Pofung BF-T11 FRS radios to be able to transmit on the Repeater input frequency of Channel 19, so now I can use them on a nearby repeater, too!

[SteveShannon]

1 hour ago, WRVG593 said:

Well what if they were to offset -3Mhz instead? Or are all of them regulated to be offset by 5mhz so that general FRS radios are unable to communicate with it?

Here’s the regulations regarding frequencies. Note that repeaters are only permitted to transmit in the “a) 462 MHz Main Channels”:

a) 462 MHz main channels. Only mobile, hand-held portable, repeater, base and fixed stations may transmit on these 8 channels. The channel center frequencies are: 462.5500, 462.5750, 462.6000, 462.6250, 462.6500, 462.6750, 462.7000, and 462.7250 MHz. 

(b) 462 MHz interstitial channels. Only mobile, hand-held portable and base stations may transmit on these 7 channels. The channel center frequencies are: 462.5625, 462.5875, 462.6125, 462.6375, 462.6625, 462.6875, and 462.7125 MHz. 

(c) 467 MHz main channels. Only mobile, hand-held portable, control and fixed stations may transmit on these 8 channels. Mobile, hand-held portable and control stations may transmit on these channels only when communicating through a repeater station or making brief test transmissions in accordance with § 95.319(c). The channel center frequencies are: 467.5500, 467.5750, 467.6000, 467.6250, 467.6500, 467.6750, 467.7000, and 467.7250 MHz. 

(d) 467 MHz interstitial channels. Only hand-held portable units may transmit on these 7 channels. The channel center frequencies are: 467.5625, 467.5875, 467.6125, 467.6375, 467.6625, 467.6875, and 467.7125 MHz.

[WRVG593]

1 hour ago, Sshannon said:

Here’s the regulations regarding frequencies. Note that repeaters are only permitted to transmit in the “a) 462 MHz Main Channels”:

a) 462 MHz main channels. Only mobile, hand-held portable, repeater, base and fixed stations may transmit on these 8 channels. The channel center frequencies are: 462.5500, 462.5750, 462.6000, 462.6250, 462.6500, 462.6750, 462.7000, and 462.7250 MHz. 

(b) 462 MHz interstitial channels. Only mobile, hand-held portable and base stations may transmit on these 7 channels. The channel center frequencies are: 462.5625, 462.5875, 462.6125, 462.6375, 462.6625, 462.6875, and 462.7125 MHz. 

(c) 467 MHz main channels. Only mobile, hand-held portable, control and fixed stations may transmit on these 8 channels. Mobile, hand-held portable and control stations may transmit on these channels only when communicating through a repeater station or making brief test transmissions in accordance with § 95.319(c). The channel center frequencies are: 467.5500, 467.5750, 467.6000, 467.6250, 467.6500, 467.6750, 467.7000, and 467.7250 MHz. 

(d) 467 MHz interstitial channels. Only hand-held portable units may transmit on these 7 channels. The channel center frequencies are: 467.5625, 467.5875, 467.6125, 467.6375, 467.6625, 467.6875, and 467.7125 MHz.

Much more of an answer. So from what I understand and has already been said, repeaters can only emit 462.xxx range. Thank you! Not a repeater owner anyway. Just curious about how things work and why they're done the way they are.

[WRUU653]

24 minutes ago, WRVG593 said:

Just curious about how things work and why they're done the way they are

That’s the best way to be. 

[KAF6045]

20 hours ago, WRVG593 said:

User1: TX on 467.550 onto repeater1

Repeater1: catches the signal and puts out 467.550 to radio listening units and more importantly repeater2, shuts off possible incoming traffic for however long the transmission is.

Repeater2 catches, pushes out 467.550 as well.

You have just set up a feed-back loop, anything repeater 1 pushes out will be /received/ by repeater 1 -- besides not having any way to protect the receive circuit from the power level of the transmitter (other than to separate the receiver from the transmitter [antennas] by a few hundred+ feet -- lots of coax to run, with lots of power losses).

[JeepCrawler98]

What you're looking to do is called linking - there's several ways to pull this off, the more modern being VoIP linking. You can't just flip one repeater over and put them together and expect to hear anything other than just a giant feedback loop.

If you're not wanting to use IP hardware to link repeaters together, you can use a simplex link radio between them - GMRS allows this in the 467 main channels (this would be considered fixed-to-fixed station), and while it can be done effectively, it's not without it's challenges since your link radio is transmitting fairly close to your repeater's receiving frequency when there's traffic. It requires very sharp filtering, careful antenna selection so that the link radio is in the repeater's "null", excellent repeater hardware with a very selective receiver, and lots of vertical separation between your repeater antenna and link antenna. You'd also want to reduce power on your link radio as much as possible (a couple watts), use a directional antenna to recover the reduced power on both ends of the system, and you'd also want to plan your spectrum use so that they're on opposite ends (eg. your repeater listens on 467.550 and the link radio transmits on 467.725 to the other repeater, which could be on 467.550 if there's minimal overlap, but most likely 467.575). All three frequencies need to be clear and not in a position to interfere with other GMRS repeater stations (this is a non-start if you live in an urban area)

This is not exactly a newcomer type setup, but it can work well.

Again, this is if you do not want to use an IP or other telephonic type setup (T1) - which you should seriously consider doing, it's much easier to just use the internet, and if you don't want to use the internet, private IP gear using ubiquity or mikrotik is really not very difficult to set up (but does require line of sight between sites)

I'm also assuming you'd want to follow the rules and not use MURS for linking, which would be the easiest approach but has ethical decisions to be made.

Edited January 13, 2023 by JeepCrawler98

[SteveShannon]

59 minutes ago, JeepCrawler98 said:

What you're looking to do is called linking - there's several ways to pull this off, the more modern being VoIP linking. You can't just flip one repeater over and put them together and expect to hear anything other than just a giant feedback loop.

If you're not wanting to use IP hardware to link repeaters together, you can use a simplex link radio between them - GMRS allows this in the 467 main channels (this would be considered fixed-to-fixed station), and while it can be done effectively, it's not without it's challenges since your link radio is transmitting fairly close to your repeater's receiving frequency when there's traffic. It requires very sharp filtering, careful antenna selection so that the link radio is in the repeater's "null", excellent repeater hardware with a very selective receiver, and lots of vertical separation between your repeater antenna and link antenna. You'd also want to reduce power on your link radio as much as possible (a couple watts), use a directional antenna to recover the reduced power on both ends of the system, and you'd also want to plan your spectrum use so that they're on opposite ends (eg. your repeater listens on 467.550 and the link radio transmits on 467.725 to the other repeater, which could be on 467.550 if there's minimal overlap, but most likely 467.575). All three frequencies need to be clear and not in a position to interfere with other GMRS repeater stations (this is a non-start if you live in an urban area)

This is not exactly a newcomer type setup, but it can work well.

Again, this is if you do not want to use an IP or other telephonic type setup (T1) - which you should seriously consider doing, it's much easier to just use the internet, and if you don't want to use the internet, private IP gear using ubiquity or mikrotik is really not very difficult to set up (but does require line of sight between sites)

I'm also assuming you'd want to follow the rules and not use MURS for linking, which would be the easiest approach but has ethical decisions to be made.

I never thought about using Fixed Stations to connect two different Repeaters.  If that's correct (I don't recall anything in the regulations that prohibits it) then you might as well use full duplex.  Fixed Stations may transmit on both 462 MHz main channels and 467 MHz main channels, thus they could communicate in full-duplex. They are limited to lower power, but that helps with the technical challenges anyway, as you pointed out. The technical challenges you mention are the biggest challenges.

[Repeater] <--- wired connection ---> [Fixed Station] ((((((RF)))))) [Fixed Station] <--- wired connection ---> [Repeater]

[JeepCrawler98]

3 hours ago, Sshannon said:

I never thought about using Fixed Stations to connect two different Repeaters.  If that's correct (I don't recall anything in the regulations that prohibits it) then you might as well use full duplex.  Fixed Stations may transmit on both 462 MHz main channels and 467 MHz main channels, thus they could communicate in full-duplex. They are limited to lower power, but that helps with the technical challenges anyway, as you pointed out. The technical challenges you mention are the biggest challenges.

[Repeater] <--- wired connection ---> [Fixed Station] ((((((RF)))))) [Fixed Station] <--- wired connection ---> [Repeater]

You could; there's just a few extra considerations when going that route -

1. You will (presumably) have higher transmit power on the repeater output site that will make the RX side in the 462 band more difficult to manage
2. This could let FRS users make their way onto the repeater
3. Your system will potentially have presence on 3 of the 462 main channels.

[WRUU653]

14 minutes ago, JeepCrawler98 said:

You could; there's just a few extra considerations when going that route -

1. You will (presumably) have higher transmit power on the repeater output site that will make the RX side in the 462 band more difficult to manage
2. This could let FRS users make their way onto the repeater
3. Your system will potentially have presence on 3 of the 462 main channels

Seems like there is enough reasons that this isn’t a good idea to implement yet I really like the shared information and thoughts on this… cool stuff JeepCrawler98 and Sshannon!

[WRVG593]

9 hours ago, KAF6045 said:

You have just set up a feed-back loop, anything repeater 1 pushes out will be /received/ by repeater 1 -- besides not having any way to protect the receive circuit from the power level of the transmitter (other than to separate the receiver from the transmitter [antennas] by a few hundred+ feet -- lots of coax to run, with lots of power losses).

Well that's why earlier in the thread I said to set up the repeater to not receive within a certain amount of time. I was asking hypothetical. If you set a repeater to close its rx after the end if the transmission, could it then work? 

[SteveShannon]

5 hours ago, WRVG593 said:

Well that's why earlier in the thread I said to set up the repeater to not receive within a certain amount of time. I was asking hypothetical. If you set a repeater to close its rx after the end if the transmission, could it then work? 

No - it really couldn’t.  A repeater works by transmitting while it receives.  If you disconnect the receiver while it’s transmitting you prevent the repeater from repeating; it has nothing to transmit. 

Repeaters are only able to work because

1. transmitters transmit on a completely different frequency from the receiver AND
2. duplexers (or antenna locations) filter out the high power RF that is being transmitted to prevent it from entering the receiver and causing feedback or actual damage.  

The input stage of a receivers must be very sensitive to “hear” a signal at any distance.  Being connected to the same feedline as a transmitter is like having a gun go off right next to your ear.

Turning off a receiver after the transmitter has completed transmitting does nothing but prevent future use of the repeater.